Humor in Brain-damaged Patients and Neurologically Intact Young and Old People

Prathiba Shammi

A thesis subrnitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Psycho Iogy University of Toronto

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The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substanîiai extracts corn it Ni la thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son pemiission. autorisation. Tu my parents Nirmala and Krishna Bhat for providing me witlr the opportunities they didn 't lame HUMOR IN BRAIN-DAMAGED PATIENTS -AND NEUROLOGICALLY INTACT YOUNG AND OLD PEOPLE Prathiba Shammi Ph-D. 1997 Abstract Hurnor occupies a special place in human social interactions, fulfilling many fictions

ranging fiom the communication of ideas, to the use of humor in therapy. The general

objective of the present study was to extend previous research on humor in neurological

patients. In particular, the specificity of the brain pathology, and the potential psychological processes underlying humor appreciation, were investigated. It was hypothesized that the

fionta! lobe and in particular, the right fkontal region, was especially relevant to hurnor. Only patients with focal lesions restricted to the following five brain regions were included - left fiontal, right fiontal, bilateral fiontal, left posterior, and right posterior. Tests designed to examine different aspects of verbal and nonverbal humor appreciation and humor production were administered. In addition, psychological processes such as working memory, mental

Bexibility, abstraction, visual search, and focused attention were examined in relation to humor appreciation. The results indicated that patients with lesions in the fiontal lobe were more impaired than with posterior lesions. Despite the verbal nature of the humor appreciation tests, patients with pathology involving the rîght fiontal region were most irnpaired. Patients with right fiontal lesions also exhibited extremely muted physical-emotional reactions to hurnorous stimuli and were impaired in the production of humor. When performance on hurnor appreciation tests was correlated with that on tests assessing various psychological processes, the following distinct pattern of associations was obtained. Workuig memory, mental shifting, and abstraction were related to the appreciation of verbal humor. Working memory, visual iii search, and focused attention were related to the appreciation of cartoon humor. The findings were discussed in terms of a deficit involving integration in patients with fiontal damage. It is argued that integration of various types of information are important, with the integration of cognitive with affective information being critical to the highest of mental Functions mediated by the fiontal Iobe, such as self-awareness and humor. Many features of the right fiontal Iobe, e.g., anatomy, processing style, role in episodic memory and self-awareness, and type of information processed, makes this the ideal substrate for mediating humor. This dissertation would not have been possible without the help of a number of individuals. First and foremost, 1 would like to express rny sincere and deepest gratitude to my supervisor, Donald T. Stuss, who was always generous with his time and advice. His vast knowledge and experience guided me through this learning process. His constant support, encouragement, and enthusiasm for this project was inspiïing and helped me rnaintain my good humor throughout this undertaking. I am also very gratefûl to the members of my thesis cornmittee, Morris Moscovitch and Endel Tulvhg, who fieely shared their knowledge and expertise and provided many valuable suggestions. I would like to thank Hiram Brownell for permission to use test material and for suggestions regarding test design. 1 wish to thank Malcolm Binns for his ready advice and assistance with statistical analysis and Antoinette Savas for her contributions in brain lesion analysis. 1 also wish to acknowledge the collective suppoa of Paula Matthews, Rebecca Dempster, Julia Hong, Heidi Roesler, and al1 the staDFat Rotman Research Institute. The Rotman Research Institute, under the leadership of Donald T. Stuss, provided me with the ideal environment in which this dissertation could be accomplished. My specia! thanks to my husband C. Shammi and son Rohan for their support, encouragement, and rnost of al1 their patience during the pst few years. Financial support for my graduate studies was provided by Simcoe Special fellowships, University of Toronto Open Doctoral Fellowships, and Medical Research Council gants to Dr. Stuss. TABLE OF CONTENTS

I. Introduction ...... I LX .Review of Literature ...... 4 Introduction ...... 5

1. Humor appreciation in brain-damaged patients ...... 8 2 . Right hemisphere hctions involved in humor ...... 12 (a) Language ...... 12 (b) Personaliw and emotion ...... 22 (c) Processing of incongruity...... 25 (d) Cognitive processing style ...... 26 3 . Hurnor production 1 expression ...... 28 4 . Frontal lobe and hurnor ...... 31 (a) Language ...... -35 (b) PersonaIiY and emotion...... 39 5 . Humor and functions mediated by the frontal lobe ...... 42 (a) Problem solving ...... 42 (b) Working memory ...... 46 (c)Cognitive flexibility ...... 48 (d) Visual directed attention ...... 50 6 . Metacognition and humor ...... 51 7 . Self-awareness and humor ...... 52 8. Aging and hurnor ...... 58 III .Method ...... -66 IV. Results ...... 87 V . Discussion ...... 117 VI-References ...... 180 W .Appendix ...... 198 1. INTRODUCTION

The ability to appreciate and produce humor is a cognitive ability that is not only unique to humans, but is also one of the most intriguing. Humor is a basic ingredient of social communication, providing an effective means of communicating a wide range of ideas, feelings, and opinions (Brownell & Gardner, 1988). It is a key element in the human behavioral repertoire - so much so that many consider it a defining human attrîbute (Nahemov, 1986). It is such a highly valued and desired attribute that very few people are willing to admit to a lack of a sense of humor. Omwake (1937) and Allport (1961) reported that among college students only 1.4% and 6% respectively were prepared to admit to a lower-than-average sense of humor. Humor provides individuals with an important and much sought after source of pleasure, so that we often try to put ourselves in situations where humor is present. Hurnor is ais0 seen to be therapeutic. It is said that "laughter is the best medicine". The therapeutic properties of liumor have been recognized since ancient times and is stated in the biblical Proverbs 17:22 "a merry heart doeth good like a medicine". Goldstein (1 982) presented a senes of testimonials to the value of hurnor to health, citing a number of physicians and philosophers from the 12th through the 19th centunes. Lefcourt and Martin (1986) in their book "Humor and Life Stress: AIAntidote to Adversity" speculate on the purpose of humor in the hurnan species and suggest that humor and laughter represent an important mechanism for coping with many of the psychosocial stressors that humans encounter in their daily lives. It is their contention that humor and laughter are important in the maintenance of both psychological and physiological health and well-being in the face of stress. Fry (1986, 1992), professor emeritus of the Stanford University Medical School, reviewed humor physiology and concluded that humor and the mirthhl responses associated with it have many positive and beneficial eEects. The advantages of humor were reported to be jointly ernotional, psychological, and physiological, and as being additive to each other. For instance, hghter was shown to provide muscle stimulation, muscle relaxation, and cardiac muscle exercise, as well as a total body workout. The elicitation of humor was recommended to provide some conditioning exercise to wheelchair-bound and bedridden patients. That is, a good laugh is considered to act as a 'mini work-out' and stimulates the cardiovascular, respiratory, and nervous systems. The respiratory value of humor and laughter involves a disruption of the normal cyclic breathing pattern, increased ventilation, and accelerated exchange of residual air, thereby enhancing blood oxygen levels. It is recommended for patients with chronic respiratory conditions for aiding ventilation and clearing mucus plugs. The increases in heart rate and blood pressure that occur during laughter can exercise the myocardium and increase arterial and venous circulation. This causes an increased movement of immune elements and ptlagocytes throughout the system, helping the body to fight infection. Thus, the hurnor channels on closed-circuit televisions provided by some hospitals is suggested as serving multiple purposes (Fry, 1986, 1992). Hatfield (1996) described humor as a powefil force that is universal, always available, and personally controlled. Doctors were advised to use humor to enhance their daily lives as well as the lives of those around them. Similarly, Cushner and Friedman (1989) concluded that humor and laughter are an integral part of both the life and career of a physician. Though the evidence regarding the positive effects of humor and laughter on health appears to be largely anecdotal, attempts are underway to provide empirical support for this belief. For instance, evidence is available regarding the relationship between humor and its positive effect on the immune system. The protein salivary imrnunoglobin A (S-IgA) is regarded as the body's first line of defense. Low concentration of S-IgA have been found to be associated with increased infection and disease. Concentration levels of (S-IgA) have been reported to increase following presentation of humorous stimuli (Dillon, Minchoff, & Baker, 1985; Lefcourt, Davidson-Katz, & Kueneman, 1990). The implication is that humor enhances immunity and that long-term benefits may be realized by incorporating humor as a coping style into everyday life. With respect to the central nervous system, increased endorphin and catecholamine levels may be responsible for the beneficial effects of humor (Fry, 1986, 1992). Schachtet and Wheeler (1962) studied the effect of humor responsivity to pharmacological manipulation of the sympathetic nervous system by administering injections of epinephrine, chlorpromazine (a tranquilizer), and placebo saline. The epinephrine subjects were more amused by humor stimuli than were placebo subjects who were more arnused than chlorpromazine subjects, i.e., the humor response was a function of the degree of excitation of the sympathetic nervous system. Levi (1965) tested the effects of humor exposure by determining the arnount of endogenous adrenalin excreted following exposure to humorous stimuli. Urine assays demonstrated increases in catecholamine levels (significant increase in adrenalin and noradrenalin excretion) following the viewing of an amusing film. That is, humorous experience was accompanied by increased sympathetico-adrenomedullary activity. Preliminary results of a pilot snidy by Fry and colleagues (reported in Fry, 1992) indicated that catecholamine activation can be intense during humor exposure and correlates with degree of laughter. The data, obtained korn direct venous samplùig during exposure to hurnor stimuli, suggested a complex autonornic response with each catecholamine element (epinephrine, norepinephrine, and dopamine) having its own individual response pattern. Fry (1986; 1992) suggested that these increased catecholamine levels were responsible for the beneficial effects of humor on mental fünctions, such as increased alertness, leaming, creative thinking, and memory. Thus, hurnor plays a powerful and unique role in human life with wide-ranging effects on many aspects of functioning. Despite a lack of solid scientific evidence, many physicians, nurses, and psychotherapists are currently sold on the therapeutic value of hurnor and have incorporated it as an adjunct to traditional medical treatment. The present study examined the disorder of this key human characteristic as caused by focal neurological disorder. Hurnor is hypothesized to be a multifactorial function, consisting of different types, and associated with several psychological processes. In this study, the investigation of humor focused primarily on the appreciation of humor and the production of humor. The appreciation of humor was defïned as the ability to laugh at or respond appropriately when a joke is told, or as measured by ratings of humor stimuli. The production of hurnor was dehed as the ability to tell a joke and create humorous captions to cartoon stimuli. Specifically, an attempt was made to identify whether - (1) there are individual differences in the appreciation and production of humor; (2) a disorder or individual differences in hurnor can be attributed to any specific cognitive mechanism or psychological process; (3) damage in any particular brain region causes a disorder in the appreciation or production of hurnor; and (4) there may be an association between lesion site, cognitive mechanism, and the ability to appreciate humor orbe humorous. II. Review of Literature

Introduction Studies 1. Hurnor appreciation in brain damaged patients 2. Right hemisphere functions involved in humor (a) Language (b) Personality and emotion (c) Processing of incongruities (d) Cognitive processing style 3. Hurnor production/expression 4. Frontal lobe and humor

(a) Language (b) Personality and emotion 5. Hurnor and functions mediated by the fiontal lobe (a) Problem solving (b) Working memory (c) Cognitive flexibility (d) Visual directed attention 6. Metacognition and humor 7. Self-awareness and humor 8. Aging and humor 5 In traduction Humor has been studied primarily in disciplines such as philosophy and literature, with little empirical investigation in psychology until recently. McGhee and Goldstein (1983) noted, "The history of humor research prior to the 1970s cm be charactenzed in terms of the short-term cornmitment to investigating hurnor among those who did venture out and try their hand at designing humor studies. For reasons that remain unclear, many investigators pubIished only one or two humor studies before abandoning the area in favor of some other research domain. We have the impression that for decades social scientists have been very intrigued by the idea of studying humor. Psychologists have suspected for a long time that humor somehow is very important in the lives of people. We find Iaughter and humor occurrïng almost wherever we hd people engaged in social interaction. The fact that we usually feel better when we laugh suggests that laughter rnay somehow be important for our health and well-being." There are at least three reasons postulated for the lack of interest in hurnor research by psychologists. One reason rnay be methodological. Humor remains an elusive concept with little agreement on how it should be defined or measured. Second, many scientists feel that humor is a "fnnge" area of research. When we don't understand more apparently salient problems and questions such as cancer, nutrition, basic properties of mernory, how can we justiQ spending outirne studying humor? (McGhee & Goldstein, 1983). Third, humor is difficult to define operationally. The Webster's dictionary (Webster's encyclopedic unabridged dictionary of the English language, 1989) has the following definition: "Humor consists principally in the recognition and expression of incongruities or peculiarities present in a situation or character. It is firequently used to illustrate some fundamental absurdity in human nature or conduct"; "the faculty of perceiving what is arnusing or comical or the faculty of expressing the amusîng or cornical". Without precise definition, the development of scientific methodoIogies is difficult. In the 1970s, a small number of brain - behavior researchers began to take interest in humor for several reasons. First, humor involves both cognitive and affective dimensions. To recognize that something is funny contains both emotional and cognitive elements. Brain damage often results in some degree of impairnient in both the cognitive and affective status of the individual. However, as Gardner et al. (1975) point out, these two facets of the individual are usually examined in complete independence of one another. The realm of humor provides a unique opportunity to study the interplay between both dimensions. 6 Second, neuropsychology has recently ventured into research into areas of the human psyche that were previously considered to be beyond the realm of scientific investigation. These include topics such as self-awareness, self-reflection and consciousness. Humor is another such subject matter. Some scientists claim that these topics cannot be operationally defined or measured and therefore not suitable areas of research. However, it is important to study these topics in relation to the human brain. They are among those capacities that are at the core of what makes us distinctly human. They represent evolved skills that serve important biological and social functions and enrich hurnan lives. These uniquely human abilities must likely be the consequence of the iremendous complexity achieved by the human brain through evolution and the cornplex cognitive processes that it alone is capable of. These topics provide an avenue to study higher-order brain-behavior relationships. Anecdotal observations and case studies paved the way for understanding that a relationship exists between brin damage and humor. Darnage to certain areas of the brain causes dramatic changes in emotions and personality. In addition, there may be a disturbance of the 'sense of self (Stuss & Benson, 1986). In the well known case of Phineas Gage, following severe frontal lobe injury, his emotional behavior and personality were so significantly changed that his friends stated that he was a different person: 'No longer Gage" (Harlow, 1868). Similady, earIy studies indicated that brain darnage can also result in disorders in the appreciation and production of humor (reviewed in later sections). Since the ability to be humorous and to appreciate hurnor contributes to our personality, the neurological basis of hurnor competence should be studied. There is some suggestion that darnage to certain areas of the brain rnight lead to deficits in different aspects of cognitive abilities that rnight be related to humor appreciation and production. References to the sense of humor of brain damaged patients can be found, often in relation to changes in personality or deficits in linguistic ability as a result of brain injury. For instance, certain types of aphasia are reported to exert devastating effects upon the individual's ability to synthesize the elements involved in a joke or cartoon (Head, 1926; Critchley, 1971; Luria, 1970). However, generally such evidence is anecdotal and Me, if any, systematic evidence has been gathered on the ability to appreciate hurnor among patients with various brain lesions (Gardner, et al., 1975). Given the short history of ernpirical psychological research into the domain of humor, it is not surpnsing that there have been even fewer investigations into its neuropsychological aspects. Although attempts specifically aimed at neuropsychological study of humor are scarce, available 7 evidence shows mat particular brain regions may play an important role in humor. This literature is reviewed below.

Studies This chapter reviews available studies relevant to the neuropsychology of hurnor. The literature review is organized into sever. main sections. The first section surnrnarizes investigations of humor appreciation and cornprehension in brain darnaged patients. niese consist largely of a series of studies by Gardner and colleagues. The focus of their studies was on identifying the cognitive processes involved in the cornprehension of humor, and delineating how damage to particular brain regions disrupts these processes to produce humor deficits- This gmup of studies suggested right hernisphere involvement in humor appreciation. In the second section, deficits in humor caused by right hemisphere damage are related to a characteristic profile of other deficits following right hemisphere iesions. These deficits are in the area of linguistic and narrative abilities, as well as in personality and emotions. Also, right hemisphere role in humor processing is related to its role in processing incongmities and its characteristic processing style. The third section deals with the productive or expressive aspects of humor- Research in this area of hurnor has been largely ignored. The literature in this section consists mainly of incidental observations regarding deficits in the expression of hurnor in nght hemisphere patients. The fourth section reviews the literature suggesting a role for the frontal lobes in hurnor processing. It deals with changes in language, personality, and ernotions foIlowing fiontai lobe lesions and highlights the fact that these changes paralle1 deficits observed in right hemisphere patients. The fifth section describes some of the cognitive processes considered to be mediated by the fiontal lobes, such as problern solving, working memory, cognitive flexibility, abstraction, and visual directed attention and indicates how these functions play an essential role in humor. The next two sections are concerned with two functions - metacognition and self-awareness, which are of particular relevance to the fiontal lobe and considered to be among the highest of al1 integrated brain activities. These sections outLine how these two functions relate to hurnor. The last section reviews studies concemed with fiontal lobe changes in aging and discusses how the study of humor is relevant to aging. Literature on the frontal lobe dealing with changes in language, personality, emotion, and self-awareness following damage to the right f?ontal lobe suggests that this region may be especially important in humor processing. 1. Humor appreciation in brain-dama~edpatients Research in this area has mostly dealt with cognitive processes involved in humor appreciation. Compelling evidence for the role of the right hemisphere in humor comprehension was provided in a series of interesting studies by Gardner and associates. These studies were designed specifically to study cornprehension of humor in brain darnaged patients and to identify the cognitive processes involved.

In the first of these studies, Gardner et al. (1975) showed a senes of cartoons ;O both right and left hemisphere patients with instructions to choose the 'funniest' of four cartoons. The effect of verbal captions and attention to detail were studied. Ability to detect the most humorous cartoon was impaired in dl brain damaged patients, more in severe than in mild aphasics, but there was no significant difference between patients with left and right hemisphere lesions in their overall performance on the test. A different order of difficulty across items and a different profile of 'mirth' responses to the items did, however, correlate with site of lesion. Left hemisphere patients perforrned better on captionless items and behaved in a rnanner which more closely approximated normal subjects in their humorous reactions, their order of difficulty, and their explanations. In contrat, right hemisphere patients showed much more variability in their laughter; Le., they were much more likely to show either extremely high arnounts of laughter throughout, or more fiequently, no laughter at all, they often confabulated answers or made impossible references, and they performed better on items with captions. Their cognitive reactions also appeared 'dissociated' f?om their affective responses. That is, extreme Iaughter often occurred in the absence of evidence of cornprehension, and cartoons that were understood were fiequently accompanied by absence of any laughter. They concluded that these findings were consistent with the view that the right hemisphere may be especially important for the production of emotionalIy appropriate responses (Gainotti, 1972; Gardner, 1975). In the next study, Wapner et al. (1981) found that in comparison to normal subjects, right hemisphere patients showed a reduced ability to offer a reasonable explanation for cartoon humor and chose both a significantly lower percentage of correct choices of the funniest caption fiom among four possible captions (joking, non sequitur, straightforward neutral, and straightforward sad) and a greater percentage of non sequitur endings as funniest. They concluded that the result with non sequiturs suggests that the right hemisphere patients recognize the importance of the form of a joke but they have difficulty fully interpreting a joke's content. That is, both the correct punch line and the non sequitur satisfied the normal prerequisite for a joke (not directly 9 following kom the joke stem), but the non sequitur lacked meaningful coherence. Right hemisphere patients also showed less differentiation (in ternis of funniness ratings) between funny and unfunny items than did normals. This resulted fiom their tendency to give higher ratings to the unfunny items; their ratings for stimuli recognized as jokes were comparable to those of normals. Also, while right hemisphere damage may be rnost disruptive of the ability to appreciate unfamiliar humor, memory for old humor may not be affected. This view was based on right hemisphere patient's ability to still tell previously rnemorized jokes and to distinguish familiar foils from unfamikir ones. The next two studies in this series (Brownell et al., 1983 and Bihrle et al., 1986) investigated the two cognitive components hypothesized to be essential for the intact appreciation of jokes and cartoons, based on the Incongruity - Resolution model of humor. Deficits in these cognitive components was studied in relation to brain damage. Brownell et al. (1983) exarnined two components of jokes, "surprise" and "coherence", which are utilized in the normal appreciation of verbal humor. These two dimensions correspond well to the two-stage theories of humor, such as the Inconpity - Resolution model of model processing (Shultz, 1976; Suls, 1972). According to this model, when presented with the body of a joke, a listener formulates an expectancy; then, upon hearing the punch line, the listener perceives an incongruity vis-à-vis the expectancy based on the beginning of the joke. The listener is then motivated to resolve the incongruity either by retrieval of information in the joke or cartoon, or fiom hisher own storehouse of information. Humor results when the incongruity is resolved; that is, the punch Line is seen to make sense at some level with the earlier infoxmation in the joke. The listener, then, makes the incongruous punch line fit with the rest of the joke by revishg the initial interpretation, thereby establishing coherence. The success of a joke therefore rests on the goodness of fit between a punch line and the body of a joke once the incongniity of the punch line has been appreciated. Lacking a resolution to the incongniity, the listener does not "get" the joke, is pwzled, and sometimes even fiustrated. The resolution phase is seen to be a form of problem-solving, an attempt to draw information or inference that make a link or provide a fit between the initial body of the joke, cartoon, or situation and its ending. As noted above, this analysis identifies two potentially separable components of jokes, surprise and coherence. It is assumed that the individual listening to the joke has an intact understanding of the ordinary rneanings and uses of language, and also possesses a schema or script which covers the nomal course of events. Against this background, the individual must be 10 able to detect discrepancies fiom the normal course (sensitivity to surprise). However. in order to appreciate the joke, mere detection of discrepancy is not sufficient; the listener must be able to appreciate the relation among the elements in the body of the joke and keep them sufficiently in mind so that he can attempt to relate them to the punch line (appreciation of coherence). Brownell et al. (1983) investigated verbal humor deficits in nght-hemisphere-damaged patients using the above model. The possible dissociation between surprise and coherence elements of jokes was tested by using the Joke completion task. Subjects were asked to select fkom four types of alternatives the appropriate ending to a joke. Right-hemisphere patients exhibited a selective attraction to endings which contained an element of surprise but which were not othenvise coherent with the body of the joke. These findings suggested that right-hemisphere patients showed preserved sensitivity to surprise but had difficulty in integrating content across parts of a narrative. i.e., an impaired ability to establish coherence. These results confirmed the psychological reality of the proposed distinction between the surprise and coherence elements of humor processing. To Merinvestigate deficits in comprehension of hurnor in brain-damaged patients using the same rnodel, Bihrle et al. (1986) tested right hemisphere-damaged 0)and Ieft hemisphere- damaged (LHD) aphasic patients on a nonverbal cartoon completion test that included a hurnorous (Joke) and a nonhumorous (Story) condition, as well as a verbal analog of the test. RHD patients perfomed worse than LHD patients in both the Joke and Story conditions. Also, the pattern of errors for the RHD goup was different fiom that for the LHD group in the Joke condition, while the two patient groups produced similar error patterns in the Story condition. The qualitative difference between the errors produced by the two groups suggested that right and left hemisphere brain damage impairs different components of narrative ability. RHD patients showed a preserved sensitivity to the surprise element of humor, and a diminished ability to establish coherence. Conversely, LHD patients when they erred showed an impaired sensitivity to the surprise element of humor, and a preserved ability to establish coherence by integrating content across parts of a narrative. These results further suggested that the observed humor comprehension deficits of RHD patients resulted specifically fiom right hemisphere disease and not fiom brain damage irrespective of locus. Brownell and Gardner (1988) summarized the results Çom their studies on humor in the following account: Damage to the right hemisphere selectively affected patients' abilities to process one of two major components of humor: the ability to revise an initial interpretation in order to integrate a sentence (or ha1 fiame of a cartoon strip) back with what has corne earlier in a Il discourse. This ability figures prominently in the comprehension of both humorous and nonhumorous material. It seems to have some close comection to the right hemisphere, since the same deficits are not seen with damage to other regions of the brain. Finally, there is some support for a separation among types of humor. The right hemisphere patients seem to retain an appreciation of simpler, slapstick hurnor that does not require integration of content across sentences or across fiames in a cartoon strip. Right hemisphere patients' impairment in the comprehension of humor is further supported by Dagge and Hartje (1985). They investigated whether the comprehension of cartoons in these patients was predominantly influenced by a disturbance in the processing of affective material or by cognitive deficits, by presenting cartoons ciiffenng in cognitive demand to groups of right hemisphere patients, aphasics, and normal controls. Subjects were required to identie the cartoons in a multiple choice set of four pictures, as well as to rate the funniness on a three-point scale. Aphasics performed as poorly as right hemisphere patients with complex cartoons but had no difficulties with simple cartoons, suggesting that aphasics are not generally impaired in the processing of humor. Their poor performance with complex cartoons was attributed to an impairment in conceptual thinking which is a prerequisite for the understanding of complex cartoons. In contrast, right hernisphere patients had severe problems with both complex and simple cartoons, supporting the view that they have general difficulties with processing of humor. Even with simple cartoons their performance was significantly inferior to that of non brain-damaged controls and aphasics. Considering the performance pattern of the right hemisphere group led to the conclusion that the impairment in these patients was caused by a combination of visuo-perceptive and cognitive deficits rather than by an inability to identiS the affective component of cartoons. This conclusion was underlined by the observation that in those cases in which the cartoon was correctly identified, the right hemisphere patients did iiot differ from the other groups in their appreciation of humor as tested by ratings of funniness. Based on evidence that right hemisphere is involved in mental rotation and in humor processing, Johnson (1990) hypothesized that there is a cornmon substrate involved in both these processes. Hence he predicted that right hemisphere abilities, as rneasured by mental rotation, will be related to hurnor processing. That is, people who are faster andor more accurate mental rotators will also be more sensitive appreciators of humor. To demonstrate this relationship, a Humor Appreciation Scale (where participants rated jokes on a 1 to 7 rating scale, with 7 being the highest in funniness) and a Mental Rotation Task (consisting of same-shape and different shape-rotation) were 12 administered to college students. Results indicated that only the different shape-rotation times (a more difficult task than same-shape rotation) were significantly related to hurnor ratings, as faster rotation times were associated with higher hurnor ratings. Authors suggest that processing speed is the crucial variable relating mental rotation to humor ratings, that is, right-hemisphere-processing speed underlies fast mental rotation and enhanced appreciation of humor.

In summary, available research data supports right hemisphere involvement in the appreciation of humor. Sensitivity to surprise and the ability to establish coherence have been suggested as cognitive components involved in the normal appreciation of verbal hurnor. Right hemisphere patients were shown to have preserved sensitivity to surprise but had difficulty in establishing coherence. Further extension and replication of these results are required. Also, precise localization of humor processes within the right hemisphere rernains to be determined. The present study investigated the hypothesis that there may be specificity of humor processes within the nght hemisphere, with the right frontal region being the one most relevant. The evidence available with regard to right hemisphere specialization for humor are in accord with other research demonstrating deficits in language, personality, and emotions as a result of right hemisphere damage.

2. Ri~htHemisphere Functions Involved in Humor Studies reviewed thus far provide empirical support for right hemisphere involvement in humor. Deficits in humor processing associated with right hemisphere damage bear a relationship to the profile of other deficits usually observed in these patients. That die right hemisphere is important in humor is understandable when we consider its involvement in the processing of certain types of language abilities, personality, and emotions, as well as its charactenstic processing style. This evidence is reviewed below. 2(al Rkht Hemisphere and Lanmage Traditionaliy the lefi hemisphere has been accepted as being dominant for al1 linguistic functions with the belief that the nght hernisphere did not play a major role. However, clinical obsemations of right hemisphere darnaged patients suggested that the right hemisphere was also important. Recent studies have confirmed the role of the nght hemisphere in certain aspects of normal language functioning. On superficial examination right hemisphere patients appear to have preserved cornpetence when assessed in tenns of the 'Yraditional or straight" aspects of language usually studied by linguists, 13 such as phonology, syntax and sernantics. In contrast to left hemisphere patients, these patients typically have no difficulty narning objects or understanding even syntactically complex sentences. Despite their preserved capacity to understand single sentences, on clinical examination right hemisphere patients are often clearly impaired in their ability to cornmunicate (Molloy, Brownell, & Gardner, 1990). For instance, the spontaneous verbalizations of these patients are often described as being loose or rambling and given to circumlocutions and confabulations (Gardner et al.. 1953). There is growing evidence fiom recent investigations that nght hemisphere patients, despite retaining the traditional elements of language, cm still demonstrate significant deficits in certain other aspects of language. The growing reports of right hemisphere involvement in language point to its critical role in pragmatic language which deals with the uses of language, as well as paralinguistic capacities, narnely those aspects of tone and gestures that accompany language (Weylman et al., 1988). The right hernisphere patients have difficulty with the more complex and subtle aspects of language, those dealing with nonliterallfigurative and abstract language. Their difficulty with language deals more with narrative, when the unit of language is larger than a sentence requinng the combination of intersentential information. Thus, the ability to understand discourse is impaired as a result of nght hemisphere damage. Studies which lead to this conclusion are reviewed below. These studies are particularly important since right hemisphere deficit in humor has been viewed as an instance of its more general impairment in handling complex linguistic material. Right hernisphere patients' difficulty deals with the pragmatic portion of language which includes the intentions and attitudes conveyed by speech, as well as gestural and prosodic elements that accompany speech (Weylman et al., 1988). These aspects of language are critical for discourse or conversation. As Molloy et al. (1990) descnbe, "The meaning of a conversation does not follow simply fiom the meanings of the individual sentences that compose it. Instead, it is part of the nature of discourse that it requires a listener who must work to undentand how different sentences or utterances are related. To be successfÙl at this kind of understanding requires much more than a knowledge of what individual sentences mean. One must also know when words and sentences depart fiom their usual functions and how this discrepancy may relate to the speaker's own purposes or to the subject at hand" @g. 113). Discourse comprehension therefore, involves the abiliw to transcend literal meanings and requires processes such as drawing inferences, making assumptions, making predictions or revisions, and use of contextual knowledge. The focus in the present review is largely ori research on right hernisphere Ianguage deficits by Gardner and 14 colleagues, since their body of work places humor deficits within the realm of nght hemisphere impairnent in figurative language, discourse, or pragmatic language use. Right hemisphere patients have been shown to have difficulty understanding figurative languase such as metaphors (Winner and Gardner, 1977). A metaphor comprehension task was adrninistered which required selection of the correct pictonal description of a metaphoric phrase. While aphasics preferred the correct metaphoric drawings, RHDs chose literal depictions over correct metaphoric interpretations. Despite competent performance on the verbal condition, they persisted in choosing literal depictions in the pictorial condition. Gardner & Denes (1973) investigated sensitivity to denotative versus co~otative/expressive rneaning of spoken words. Although RHD patients were not the main group being examined in this study, a striking and unexpected finding was their extreme resistance to the connotative portion of the task (only 3 out of 6 subjects compieted the task), as well as their scores, which were lower than that of the average lefi antenor patient. That is, they had greater difficulty in matching words to pairs of expressive lines which varied on a single dimension (the connotation task), while exhibiting no apparent difficulty while matching a word to a set of pictures (the denotation task). The unexpected impairment exhibited by RHD patients with connotative aspects of ianguage in the above study were confinned by Brownell, Potter, and Michelow (1984). Subjects were presented with groups of three words and were required to choose the two that were rnost similar in meaning or that went together best. To make this choice, on each trial some components of meanings had to be ignored, while focusing on others. Thus, words could be judged as related either on the basis of denotative (dictionary) or connotative (expressive or allusive aspects) meaning components. A dissociation was obtained based on site of brain damage. EUDs relied more on denotative meaning relations (e-g., antonymie similarity) and avoided connotative meanings. In contrast, LKDs based their judgments largely on rnetaphor and polarity meanings based on connotation while failing to use denotative relations. Normal controls used relations representing both classes of meaning components. Thus, RHD affects understanding of connotative language, i.e., figurative language, such as words used in a metaphoric or cross-domain sense. This type of language requires the ability to tknk flexibly so that either or both connotative and denotative facets of meaning can be taken into account based on the demands of the circumstances. In contrast, LHD patients are more sensitive to connotative aspects, while exhibiting greater difficulty with canonicaVdenotative aspects of meaning, i.e., dictionary-type lexical knowledge. 15 Gardner et al. (1978) examined the capacity of patients to comprehend antonymic relations. Apart fYom canonical (well-established or dictionary) opposites, they were interested in the ability to recognize and produce noncanonical opposites (opposites in terms of domains where they have not been usuaIly recognized or words which do not normally cornmand an opposite). Three studies were conducted which assessed participants' ability to (1) provide the best opposite of a word, (2) select the appropriate opposite fiom a set of four choices in three different modalities of presentation - linguistic, representational-pictonal and abstract design, and (3) judge whether two words presented in auditory or visual modality were antonyms. Although performing at a sipificantly higher level overall compared to LHD patients, RHD patients' responses contrasted from that of the LHD group and normal controls in terms of their error patterns. That is, they offered more synonyms and associations suggesting a general weakening of the sense of the opposition. ALso, in contrast to the other two groups, who were ofien startled by the noncanonical stimuli, RHD patients were less likely to react to these relatively anomalous stimuli. RHD patients perfonned best when the opposites were highly overleamed and canonical, Le., when the production or selection of the opposite was almost automatic. With noncanonical items, providing antonymic contrasts are suggested to require flexibility in thinking, as well as sophisticated reasoning. To assess linguistic capacities of the nght hemisphere, Wapner et al. (1981) adrninistered a battery of tests. The tests featured complex narrational material in which patients were required to recall story content; arrange randomly ordered sentences into a story; abstract the point or moral of a story; and choose punch lines for jokes. RKDs had no difficulty in straight linguistic processing in that they could use appropriate phonology and syntax and recall elementary facts. However, they exhibited a striking arnount of difficulty in handling complex linguistic materials. They demonstrated impairment in organizing story elements logically, inferring the moral of a story, assessing character motivations, and choosing punch lines for jokes. There appeared to be a lack of sensitivity to narrative form in the RHD patients which was also reflected in their greater amount of embellishrnents and confabulations. In contrast to LHDs and normals, RHDs accepted and justified noncanonical or bizarre elements in a story and demonstrated better recall for these elements. The difficulty that RHD patients exhibit with linguistic matenal larger than a sentence was also demonstrated by Delis et al. (1983). In their study, patients were required to arrange the mixed-up sentences of 12 stories. In this paragraph organization task, RHD patients were found to show greater difficulty than normal controls in rearranging the written sentences to form a story. The authors interpreted these fuidings as indicating a deficit in their ability to integrate complex 16 linguistic units such as sentences, into a coherent whole, such as a story. That is. intact nght hemisphere processing was found to be important for organization of language at the paragaph level. Ioanette et al. (1986) provided Merinformation on the narrative abilities of RHD patients. An eight-fiame drawing depicting a story was presented and subjects were asked to "tell the story". Since the proposed material in this task did not have to be reorganized, this was a more namal narrative task. The Cowboy Story that was presented for narration could be segrnented into some of the basic components of a narrative structure, Le., a setting, followed by a complication, and a final resolution. Each subject's narrative was submitted to a 'propositional analysis' which provided a breakdown in terms of the amourit, the nature, and the organization of their informative content. RHD patients' narratives were found to contain less information. Also the nature of the information contained in the RHD subjects' narratives were different fkom that of control subjects. Both the RHD and control subjects were nonhomogeneous and could be distributed into two groups (1 and II) based solely on their narratives7 informative content. A majority of the RHD patients were classified as Group II. Although this group provided a lesser arnount of information, they tended to provide the gist of the story more fiequently. The results reflect a problem with the organization of narrative discourse. Brownell et al. (1986) examined the inferential reasoning ability of RHD patients, which woufd be essential for combining intersentential information and hence, for comprehension of discourse. Pairs of sentences were presented with instructions to treat them as single units or 'stones'. The correct inference was possible only if information Corn both sentences was combined, whereas information fiom a single sentence led to an incorrect inference. Thus, a sentence treated in isolation, provided misleading information. The position of the misleading sentence was varied to examine whether a rigidity of interpretation charactenzed RHD deficit. Retention of factual information presented in the sentences was also tested. Results showed that RHD patients had more trouble with inferencing than with comprehension and retention of factual ùiformation. They were also characterized b y idexibility, a selective impairment in their ability to revise their assumptions. That is, on trials in which the misleading infiormation occurred in the first sentence, they were significantly more likely than normal controls to choose the incorrect inference and significantly less likely to affirm the correct inference. As a result, they could not routinely infer the most appropnate link or conceptual bridge between individual sentences in a discourse. Authors suggest that during normal discourse comprehension, unlike normal controls, RHD patients cm appreciate 17 isolated meanings and associations, but fail to consider the importance of other relevant information. They use a limited and piecemeal understanding and are Iess concerned with achieving a coherent interpretation of the entire discourse. The authors point out that this interpretation of the RHD inferencing deficit is consonant with account of these patients' impairments in understanding other aspects of narrative understanding such as jokes (Brownell et al., 1983). RHD patients' difficulty with pragmatic or figurative language use is also reflected in their irnpairments in handling indirect requests, as well as, verbal irony or sarcasm. Comprehension of pragmatic language requires the listener to make inferences and utilize context. Foldi (1987) examined the cornprehension of indirect commmds by RHD patients. Understanding of an indirect utterance depends on the pragrnatic dimension, Le., knowledge of paralinguistic, social, or historical cues. Line drawings depicting different scenes with two individuais were presented with 10 utterances recorded for each picture. The utterances presented as a two-part exchange between the individuals in the picture consisted of (1) indirect cornmands, (2) direct commands, (3) Wh-questions coupled with (a) pragmatic responses, @) literal responses, (c) responses veri%ng the physical surround, and (d) syntacticaIly sirnilar responses. After hearing each utterance, the subject had to rate them on one of two dimensions, likelihood or politeness. RHD subjects demonstrated a selective impairment in appreciating the indirect commands. They preferred the literal interpretations of the indirect cornmands over pragmatic interpretations, in contrast to LBD and normal controls who preferred the pragmatic over the literal interpretations. That is, there was a clear dissociation in the appreciation of indirect cornmands as a result of hemisphenc site of lesion. The results showed that brain damage could lead to selective impairment of 'pragmatic' versus 'linguistic' aspects of communication. Weylman et al. (1989) replicated and extended the fuldings regarding indirect request comprehension using purely verbal material. Stimuli consisted of short vignettes that described two characters - an actor and a speaker - engaged in some activity. Each vignette ended with a question. Context and conventionality forms of the question were designed so as to bias the interpretation of the question as a request for action (indirect context) or as a literal question for fact (direct context). merhearing a vignette, participants were asked to choose the most appropriate response f?om a set of four choices: (1)an appropnate response to the question as indirect request, (2) an appropriate response to the question as a literal inquiry, (3 and 4) distractors syntactically similar to, but different in content fiom, the first two choices. The vignettes were first presented auditorily and in 18 a subsequent study, participants were allowed to read wrïtten texts of the items as they listened to them. Results indicated that RHD patients, although able to use contextual information for some interpretations, (they were more likely to choose indirect responses in the indirect context and direct responses in the direct condition), were significantly impaired relative to controls in their ability to rnake judgments based on contextual information. Molloy et al. (1990) suggest that the major finding was that unlike nonnal subjects, they did not Vary their interpretations as a function of the preceding context. Kaplan et al. (1990) Iooked at the ability of RHD patients to understand verbal irony, Le., to interpret a speaker's intended or pragmatic rneaning as guided by specific types of context. Vignettes were presented which described the affective tone of the relationship between a speaker and an actor. It also described the actor's performance on a task and concluded with a cntical sentence in which the speaker characterized the actor's performance. In the congruent context, the performance and the comment were either both positive or both negative and the speaker's utterance was literally true. In the discrepant context. the performance &luit the comment differed and the utterance needed a figurative interpretation. In order to evaluate whether an ironic statement was meant to be supportive or wounding, knowledge regarding participant relationship and speaker motivation had to be utilized. Mer hearing each vignette, subjects were given a multiple-choice question concerning the pragmatic intent of the utterance, that is, whether the speaker was (1) telling the truth; (2) joking or making fun; (3) trying to be sarcastic and nasty; (4) saying sornething wrong by rnistake; or (5) telling a lie on purpose. The RH.patients and normal controls performed similarly in the congruent conditions, while interpreting literally mestatements. In the discrepant condition, however, RHD patients were significantly less consistent compared to controls in integrating information about speaker-perfonner relationship and the actor's performance to guide their interpretations of the literally false remarks. That is, RKû patients were impaired in their ability to assign pragmatic motives accurately and to interpret a speaker's utterance on that basis. Right hemisphere invo lvement in language, particularly in discourse comprehension and pragmatic language, is demonstrated by the above studies. As Foldi (1987) suggests, "Perhaps it is in the broader temtory of communication, not just the narrower linguistic view, that the contribution of right hemisphere seems essential".

To sumrnarize, RHD patients have difficulty with complex linguistic materials and dernonstrate impainnents in (1) disceming the connotations of common words (Gardner & Denes, 1973), (2) 19 appreciating antonymie contrasts (Gardner et al., 1978). (3) interpreting figures of speech ( Winner & Gardner, 1977), (4) organizing randomly ordered sentences into coherent narratives (Wapner, Hamby & Gardner, 1981), (5) detecting bizarre or incongruent elements in a story (Wapner et al.. 1981), (6) interpreting and organizing paragraphs and stories (Delis et al., 1983; Gardner et al.. 1983, Joanette et al., l986), (7) inferential reasoning (Brownell et al., l986), (8) comprehending indirect requests (Foldi, 1987; Weylman et al., l989), (9) understanding verbal irony (Kaplan et al., 1990), and (10) choosing punch lines for jokes (Brownell et al., 1983). Su~eestedexplanations for lan.guage deficits in RHD: Several explanations have been put forth by Gardner and colleagues in an attempt to conceptualize the processes underlying the striking amount of difficulty displayed by RHD patients in handling complex linguistic material. Wapner et al. (1981) found that RHD patients could understand and remember isolated details of a story, but had difficulty integrating the information into a coherent whole, in drawing proper inferences and morals, and in judging the appropriateness or fit of different story elements. The overall pattern of their data led them to conceptualize the difficulties of these patients as due to a lack of a 'plausibility meûic', Le., they seem unable to decide, given a specific event whether or not it fits into an overall narrative structure. Unlike nomals, they lack the capacity to judge whether a particular element is appropriate within a particular context. Hence, they rnay either challenge items that are perfectly appropriate or, on the other hand, go to extraordinary lengths to justiS elernents that do not fit into a given context (e.g., an inappropnate punch line (Gardner, 198 1). Another way of characterizing the difficulties of RHD patients suggested by Wapner, Hamby & Gardner (1981) is that they have problems in acqui~ga sense of the overall gestalt or fom of linguistic entities. That is, these patients seem unable to appreciate the relations among the key points of the story or the joke. The basic schema - the major episodes organized in a hierarchically appropriate manner - seems disturbed, if not totally destroyed .... their inability to negotiate noncanonical elements, their fiequent confabulations, embellishrnents, and injections of persona1 details, al1 suggest that the basic scaffolding of the story has not been apprehended. Without an organizing principle, the patients are consigned to undirected rarnbling, unable to judge which details matter, and what overarching points they yield. Gardner (198 1) merreiterates that RHD patients lack the ability to set up a 'scaffolding' for a story. They are unable to figure out the underlying architecture or composition, the nature of, and the relationship between, the various parts and characters of a story. Instead, each part stands alone, 20 a single brick unrelated to any other - or to the entire edifice. He concludes that in fact "it is the Iefi hemisphere that, when isolated, tends to miss the point in linguistic material" (page 78). The linguistic materials that RHD patients exhibit difficulty handling could also be categonzed in terms of - (1) Size of the language units - Performance on single-word denotative tasks - such as naming and comprehension - is often preserved in RHDs, but they have difficulty when faced with more than one sentence at a time, whereas aphasics appear to be helped with longer and more redundant texts. RHDs have trouble inIèrring connections and integrating ideas in narratives. whereas LHDs manage to understand the main idea of narratives, presumably through reliance on paralinguistic cues. (2) Suprasentential contextual information - RHDs perform better on context-free situations such as determining the syntactical correctness of a word, which requires minimal additional information, while having difficulty with context-dependent situations where information fiom the surrounding context is critical - such as the relationship of a punchline to its joke, cr evaluating sarcastic intent. (3) Literal versus figurative applications of a word - Right hemisphere damage would impair handling of figurative or abstract language, such as discerning the underlying meaning of a proposition and relating it to other propositions that capture the same relationship, as in a metaphor or proverb (Weylman et al., 1988). Thus, RHD impairments in language have been conceptualized in terms of two orthogonal axes (Wapner et al., 1981; Gardner et al., (1983). The horizontal axis represents purely linguistic cornpetence. Arrayed on one end of this axis are certain canonical or 'straight' aspects of language such as phonoiogy, syntax, literal lexical entities, which may require sheer computational capacities. At the other end of this horizontal axis are arrayed more complex linguistic entities, ones which entail redundant information, nonliteral information, and information which requires integration across the boundary of the word or clause (e.g., jokes). RHD patients perform better with the more canonical aspects, while being impaired with the more complex, whereas LHD patients might display the opposite pattern. The vertical axis represents the extent to which pragmatic and paralinguistic features contribute to the comprehension of a linguistic entity. The ideal 'content-fkee' situation, e.g., a simple assessrnent of whether a word is spelled Gr defined conectly, whether a story has an appropnate beginnhg or ending, would be placed at one end. Contextual information plays a minimal role hm. At the opposite of this axis would be placed situations in which contextual information is wholly or largely determinant - telling a joke, judging the plausibility of a particular fact within an 21 adventure story or fairy tale, evaluating which of two jokes is funnier. RHD patients are more irnpaired on these contextualized linguistic assignments. Finally, another way of charactenzing RHD deficit has been in ternis of Gardner's theory of 'frames of mind'. He has suggested that much of cognitive activity involves separate analytic modules, termed fiames of rnind (Gardner, 1983). Frarnes subserving language and logical reasoning are likely to be located in the left hemisphere. In addition, successfül communication requires the ability of 'keeping frames in mind', which is a right hemisphere capacity. 'Ilils involves the ability to monitor the different analytic processes, determine when to invoke each, and shifi, when needed fiom one analysis to another. Thus, RHD patients might be capable of cai~ying out specific analyses properly, but fail to appreciate when an alternative mode of analysis is required, when the curent one is inappropriate, or when two modes need to be drawn on together. Comments on localization of language deficits within the nght hemisphere: An important question that needs to be addressed in discussing linguistic impaiments is whether these deficits apply equally to al1 RHD patients, or whether they can be differentiated on the basis of site of lesion within the right hemisphere. For instance, do these deficits occur more in RHD patients Mth anterior or fiontal lesions? However, there is no adequate answer to this question yet. First, sample sizes tend to be small. Also, in most of the studies reviewed above, RHD patients are grouped together and treated as one regardless of lesion site within the hemisphere. There have been speculations that some of these deficits could be associated more with frontal pathoIogy (Gardner, 1981; Brownell et aI., 1986). Wapner et al. (198 1) study was the only one where results were analyzed for subgroups of RHD patients. These patients were classified as (a) prerolandic or anterior; (b) perirolandic or central; (c) extensive, including anterior, temporal and parietal areas; and (d) postro landic or posterior. Although sample sizes were small, the results were interesting. Some of the characteristics often described as being typical of RHD patients were found to occur more often in those RHDs with anterior involvement. Anterior patients demonstrated a greater tendency to embellish their stories. Antenor patients also engaged in sheer confabulation more than other groups. They also showed a lack of sensitivity to noncanonical elements. Gardner (1981) cautioned that language impairments are not obtained with every RHD patient, but are more common among those with large lesions in fiontal regions of the right hemisphere. Gardner et al. (1983) while reviewing the role of the nght hemisphere in the processhg of complex linguistic materials noted that many of the results reported in their study have also been cited with reference to frontal lobe pathology. 22 Some interesting evidence is available fiom studies on patients with closed head injuries. in whom &ontal lobe damage is predominant, by McDonald (1992, 1993% 1993b) (These studies are reviewed later). These patients were found to be impaired in a variety of pra,gmatic and discourse language skills and have been interpreted within the fiarnework of fkontal lobe deficits in monitoring and regulation of performance. It therefore appears that pragmatic language skills can be irnpaired following nght hemisphere. as weil as frontal lobe lesions. It will be important in fûture studies to determine whether these deficits could be etiologically related specifically to nght frontal pathology and not to nght hemisphere lesion irrespective of locus. The present study investigated the hypothesis diat the nght frontal lobe and the functions it subserves, which also apply to narrative and pragmatic language, are especially important to hurnor. The deficits in humor and language in patients with right hemisphere darnage are often reported amidst a profile of changes in personality and emotion. These changes are reviewed next.

2(bL Personalitv and Emotion Accounts of patients with nght liemisphere damage fiequently include observations regarding changes in patients' personality and emotions. An alteration in the comprehension and production of humor has been described as a feature of the personality and emotional changes following RHD. Brownell and Gardner (1988) noted that nght hernisphere patients often present the following unusual set of characteristic deficits. Most often, their basic linguistic abiiities are intact: they are not aphasic and have liîtle trouble narning objects or understanding the syntax of sentences. However, they often exhibit a range of other irnpairments. In ternis of production, these patients show poor judgment and insight into their problems; routinely their discourse and actions are socially inappropriate. Frequently these patients are gamlous, and prone to making tangentid comments. Right hemisphere patients are also impaired in understanding the discourse and actions of others. They have trouble understanding jokes told by other people, and also often miss the gist or main point of a conversation or story. They understand what is explicitly stated, but have trouble extracting the appropriate inferences and nuances fkom communicative exchanges. They misunderstand sarcasm and indirect requests. In tahgto these patients, one often has the sense that brain damage has altered in significant ways his or her personality. In contrast, left hemisphere damaged patients are typically aphasic and have marked disorders of language involving syntax, phonology, or lexical semantics. However, they seem to be very aware 23 of their social environment. Their discourse and actions are as appropriate as can be expected. given their language disturbances. They are sensitive to their deficits. and use a variety of compensatory strategies. When talking to a left hemisphere patient, one has the sense that brain damage has seriously impaired the person's linguistic abilities, but has not drastically altered the underlying personality (Brownell and Gardner, 1988). Thus, a change fkom premorbid personality is ofien a notable consequence of right hemisphere damage. Right hernisphere darnage has also been associated with a characteristic pattem of emotional behavior. RHD has been reported to produce an indifference-euphonc reaction, which includes minimization and/or denial of syrnptoms, hate for paralyzed limb and tendency to joke (Gainotti, 1972). Similarly, right-sided injection of sodium arnobarbital into the carotid artery was associated with a euphonc-maniacal reaction with patients appearing without apprehension, smiling, and laughing (Terzian, 1964). A euphoric reaction characterized by feelings of optimism about the future, making jokes and breaking into peals of laughter was also obtained by Pema, Rosadini, and Rossi (1961) following injection to the nondominant hernisphere. In contrat, LHD has been associated with a 'catastrophic reaction' characterized by feelings of despair and anxiety, bursts of tears, and depressed renouncements (Gainotti, 1972). Sackeim et al. (1982) conducted three retrospective studies to examine hemisphenc asymmetry in the regdation of emotion. The first study which examined 1 19 cases of pathological laughing andor crying found that predominantly right-sided lesions produced pathological laughter and positive rnood changes, while left-sided insult produced the opposite pattern of pathological crying and negative mood changes. The second study which looked at mood changes following hemispherectomy, found that 12 out of 14 cases of right hemispherectomy were judged as euphoric in mood. The third study examined lateralization of foci in patients with ictal outbursts of uncontrollable laughing (gelastic epilepsy) and crying (dacrystic epilepsy). In cases of gelastic epilepsy, foci were more frequently lefi-than nght-sided. The authors reasoned that emotional outbursts in geiastic and dacrystic epilepsy are a result of excitation of regions ipsilateral to foci. Therefore the expenence of positive mood and outbursts of uncontrollable laughmg are due to excitation or disinhibition of regions in the left side of the brain. Destructive lesions, however, result in disinhibition of contralateral regions regulating emotional expenence. Thus, they suggested that the left side of the brain typically subserves positive emotion to a greater extent than the nght, whereas the reverse holds for negative ernotion. 24 More recently, Ross, Hohan, and Buck (1994) have suggested that al1 (primary) emotions are modulated by the right hemisphere whereas social emotions are modulated by the left hemisphere. This was based on the finding that following nght-sided injection of amobarbital, besides a distinct loss of spontaneous and repetitive affective prosody, alrnost all of the patients dramatically altered their recall conceming an emotionally charged life event by denying, minimizing, or decathecting the primary emotion and, in many instances, substituting a social emotion. Right hemisphere damage has also been associated with impaired processing of emotional stimuli. For instance, the affective components of language, encompassing prosody and ernotionaI gesturing, have also been proposed as dominant linguistic functions of the right hemisphere (Ross & MesuIam, 1979; Ross, 198 1, 1993). The relationship between nght hemisphere lesions and disordes of affective language (aprosodias) has been systematized and the functional-matornical organization of the affective components of language in the nght hemisphere has been show to mirror that of propositional language in the left hernisphere. Propositional language is normal is these patients. The suggestion is that the affective components of language are modulated by the right hemisphere. The aprosodias are charactenzed by such features as flat and rnonotonous speech, reduced spontaneous gesturing, poor prosodic and/or gestural repetition and impaired prosodic anaor gestural cornprehension correlating with site of lesion within the right hemisphere. Flat affect and pathological laughing and crying were also present in some. Thus, the right hernisphere plays the dominant role in the recognition and production of the affective components of language. Right hemisphere patients have also been shown to demonstrate impaired comprehension of facial ernotion. For instance, Cicone, Wapner, and Gardner (1980) found that right hernisphere patients demonstrated difficuhies when asked to recognize a face, or a facial expression, or interpret the emotion appropriate to a pictonal or a linguistically described scene. While patients with left hemisphere damage had selective difficulty with linguistically presented stimuli, right hemisphere patients exhibited an across-the-board reduction in emotional sensitivity. Moreover, right hemisphere patients also tended to group together emotions of opposite polarity (positively-toned with negatively-toned emotions). The authors suggest that in addition to its general importance in a range of emotional tasks, the nght hemisphere is crucial for an appreciation of the structural relations that obtain among various emotions. Thus, nght hemisphere damage has been associated with impaired processing (i.e., perception, comprehension, and expression) of emotional stimuli (reviewed in Heilrnan & Satz (1983). 25 Hurnor deficits of right hemisphere patients fit well into the profile of deficits in linguistic and narrative abilities, as well as personality and ernotional changes observed in these patients. The processing of humor by the right hemisphere is alço related to the kinds of information it processes and its characteristic processing style.

2(c). Processine of Incongruity Theones which attempt to explain hurnor have most cornmonly placed ernphasis on the importance of inconpity (the Incongmity-Resolution model, Shultz, 1976; Suls, 1972). Studies reviewed earlier point to the importance of the right hemisphere in the detection of surprise and the resolution of incongru@ (Wapner et al., 198 1; Brownell et al., 1983). Some electrophysio~oogical evidence is available as to how incongnllties may be processed that may have implications for humor processing. Kutas and Hillyard (1980) detected unusual brain activity during the processing of verbal incongruities. They suggest that language cornprehension cm be characterized as a continual testing and updating of hypotheses about the words that are likely to occur next in a text or conversation. Earlier research had dernonstrated that unexpected or surprising stimuli were typically followed after some 300 to 600 msec by a positive ERP component known as the P300- Therefore they investigated event-related brain potentials (ERPs) that occur when an inappropriate word occurs unexpectedly at the end of a sentence in a series of experiments where subjects silently read 160 different seven-word sentences presented one word at a time. In the kst two experiments, a random 25 percent of the sentences ended in a semantically incongruent word. The degree of semantic incongniity was either 'moderate' or 'strong'. In the next experiment, a random 25 percent of the sentences ended in a physically deviant or graphemically incongruent word (Le., larger in letter size than preceding words). Results revealed that graphernic/physical incongruities elicited a late positive complex of waves (P560). In contrast, semantic incongruities were followed by a negative component peaking about 400 rnsec after the onset of the final word (N400). The authors suggest that these negative waves appear to "reflect the interruption of ongoing sentence processing by a semantically inappropriate word and the 'reprocessing' or 'second look' that occurs when people seek to extract meaning £tom senseless sentences". Thus, the reprocessing that occurs after semantic incongruities is different fiom that caused by graphemic incongmity which may be akin to simple surprise which does not need to be resolved. 26 The reprocessing following presentation of semantic incongmities may have implications for humor comprehension which is hypothesized to involve two stages. In the first stage, incongruities are recognized and in the second, the incongruities are resolved. The resolution stage may be similar to the reprocessing that was observed with semantic incongruities. No hemisphenc differences are reported in the Kutas and Hillyard (1980) study. However, since humor studies irnplicate right hemisphere processing, it is interesting to speculate as to whether the pattern of negative ERPs might be more representative of right hemisphere activity for incongruity-based humor. Studies with normal subjects have also implicated the right hemisphere in humor processing. Svebak (1982) explored the effect of mirthfülness upon the amount of discordant right-left occipital EEG alpha production. Recordings of right and left occipital EEG alpha were related to arnount of spontaneous laughing in subjects exposed to a film comedy. Results indicated that those who laughed at the film comedy showed less discordant alpha in the right hemisphere, while discordant alpha in this hernisphere increased in the 'nonlaughers'. That is, appreciation of humor (accompanied by laughter) was associated with relatively concordant EEG alpha in the two hemispheres.

2(d). Coenitive Processinn Style It has been postulated that the two hemispheres differ in their processing styles. The lef? hemisphere is considered to be skilled at sequential processing in general and, therefore, is the more analytic of the two hemispheres. This analytic mode of information processing is thought to apply to al1 incoming information. In contrast, the right hemisphere is considered to be more adept at simultaneous processing of information, that is, it is more holistic and synthetic in handling al1 kinds of information. There is fiirther specuiation that there is a delicate balance between the two hemispheres, with one or the other taking over, depending on the task and other as yet unspecified factors (Springer & Deutsch, 1993). We cm hypothesize therefore, that perhaps hurnor experience requires sirnultaneous or holistic type of processing and therefore cm best be handled by the right hemisphere. This capacity of the right hemisphere to deal with stimuli in a simultaneous and holistic marner is also likely to be the basis for its special role in the detection of incongruous relationships, which is an important prerequisite of humor perception. 27 McGhee (1983) points out that patients with right hemisphere lesions show deficits in numerous capacities in a nonhumor context that should interfere with nomal humor appreciation as well (reviewed in the right hemisphere language section earlier). These include a reduced ability to (1) consider connotation of words. (2)interpret simple metaphors, (3) organize information into coherent sequences, (4)detect bizarre or incon,guous elements, (5) integrate details into a broader coherent whole, (6) judge plausibility of an event relative to a particular context, (7) consider interrelationships between parts, and (8) go beyond specific details to "get the point" of a message. He suggests that available data are consistent with the view that it is the right hemisphere that performs the insightful integration of key elements of information that must be meaningfully linked before the hurnor can be understood and appreciated. If the left hemisphere must fend for itseif, the individual may be surprised by the humor stimulus, but will be unable to detemine how the surprising event does rneaningfully fit in. A given joke, cartoon, or spontaneous humorous incident requires simultaneous awareness of several key bits of information represented in the current stimulus event, along with pertinent context-related knowledge derived fiom past expenence. The nght hernisphere's greater interconnectedness of neurons makes it better suited to perform this function than the left hemisphere (McGhee, 1983). McGhee (1983) hrther suggests that the two hemispheres operate in concert in processing hurnor. He outlines the interaction of the two hemispheres in handling a hurnor stimulus as follows: "Ln the case of verbally mediated humor, left hemisphere processing should predominate up to the punchline. That is, language automatically entails relational or sequential processing because words must follow each other in time. As one reads or listens to a joke, incoming information is continually related to what has been said and to what is expected to follow. In the case of straightfonvard communications, the left hemisphere is fully competent to understand statements and respond appropnately. When the unexpected and incongrnous information in a joke is delivered (in the punchline), however, the left hemisphere appears unable to go beyond registering surprise. It is the right hernisphere that cornes into play at this point and produces the simultaneous awareness of two meanings (as in a pun) or of diverse eIements that must be brought together in order to appreciate the humor potentially present" (page 3 1).

Trocessing of cartoon humor is also hypothesized to occur in a similar manner. "As the individual scans the surface of the drawing, increasing arnounts of information are picked up in sequentiai fashion. Eventually incongruous or inconsistent information will be detected. The cartoon will not be understood until other information available fi-om either the cartoon or the 28 individual's prior expenence is seen to provide a meaningful and coherent link with the elements forming the incongruity. Again, this presumably requires right hemisphere involvement. .. -. simultaneous processing in the right hemisphere plays the most important role in the humorous insight. At some level, the individual is aware of both the expected relationship and the current incongruous relationship at the sarne tirne. Sequential processing is considered to corne into play afrer the humor has been perceived, as the individual thinks about why the joke or cartoon is fùnny or othemise reflects about the contents of the punchline or drawing" (page 3 1). According to this account humor might typically involve a sequence of lefi followed by right and maybe again lefi hemisphere cognitive processing. That is, simultaneous processing associated primarily with the right hemisphere plays the key role of achieving humorous insights, although sequential processing associated with the left hemisphere will usually be involved in providing pertinent information necessary for achieving such insights. An optimal balance of right- and Ieft-hemisphere processing is considered critical for rnaximiiing the funniness of a joke or cartoon (McGhee. 1983).

To surnmarize the relationship between humor and right hemisphere, available research evidence points to the right hemisphere as playing a dominant role in processing humor. These studies show that patients with right hemisphere damage are more impaired in appreciating humorous stimuli. Deficits in appreciating humor reported in RHD patients is also related to deficits in language, personality, and emotion observed in these patients. The right hemisphere dominance for processing humor may be based on its role in processing incongniity, which is also important to hurnor appreciation, as well as its characteristic processing style (i-e-, simultaneous/holistic processing). In addition to deficits in the appreciation of humor, RHD patients have also been reported as displaying irnpairrnents in humor production.

3. Humor Production/Exoression The production of humor is an important aspect of normal humor functioning. However, studies which have investigated this ability in brain darnaged patients are remarkably scarce. Clinical observations suggest that patients with lesions in certain parts of the brain produce humor at inappropnate thes and this is often a striking and most notable feature of personality change in these patients. Humor production is therefore an important topic to be investigated in neuropsychology. 29 Although no research is available to date which has exarnined the processes important for successful humor expression, even in normal subjects, certain features cm be hypothesized as being essential. For instance, timing, sequencing of elements within the narrative, and mode of delivery would be critical features in conveying humor. These are key features exp loited by stand-up comics and comic actors. Without these, the joke telling would not be successfül. Timing, both in terms of when the hurnorous material is introduced, as well as, within the material itself, can senously affect appreciation of hurnor. That is, judging when and how to tell a joke are critical features in humor production. Timing within humor production would entail providing a proper build-up of background information leading to the punchline. This should not be too long so as to hold on to the attention and interest of the listener. It should be brief, while at the same time provide sufficient information to activate appropriate schemas fiom relevant past expenence in order to set up certain expectations in the listener. At this point, timing also involves recognition of when to provide the punchline. That is, it involves the ability to evaluate when the audience is 'ready or pnmed' to receive the punchline which disconfims their expectations which have been set up by the body of the joke. If the narrator does not utilize this sense of timing, the punch line may be given away too early, before the listener has had a chance to set up the required expectations. In this case, the punchline would not provide the elements of surprise and incongmity, which are required for hurnor appreciation. This sense of timing and sequencing of information go hand in hand. First, information that would lead the listeners to expect a particular, routine ending is presented. At the appropnate time, the punchline is delivered which is at variance with audience expectations. Successful cornedians are

expert at exploiting this timing, often pausing at this point, before the delivexy of the puncl-1'r me. Successful joke-telling also requires an appropriate mode of delivery, i.e., the joke is conveyed at a proper Pace with the nght intonation and gestures. When al1 three elernents of humor expression - timing, sequencing of information presented, and mode of delivery - are working in concert, we might expect that it provides the optimal condition for hggering the processes required for hurnor comprehension. That is, it sets up expectancies, thereby producing surprise at the incongrnous ending (punchline). At the same tirne it triggers processes required for resolution by producing simultaneous awareness of the diverse meanings possible for the punchline so it cm be meaningfully integrated with the body of the joke to produce

CO herence. 30 Weylrnan et al., (1988) point out that "humor requires pragmatic abilities. Telling a joke necessitates knowing how to sequence parts into a whole and to prepare listeners for the punchline. Careful, deliberate exposition of narrative (giving enough, but not too much, information) sets up the right cues for the punchline to succeed". Brownell and Gardner (1988) suggested that the production as well as the comprehension of hurnor may be disrupted by damage to the right hemisphere. Gardner and associates have be,- to assess the productive capacities of patients, such as the narrative abilities needed to tell a successful joke. In a preliminary effort, right hemisphere damaged patients and control subjects were asked to tell one of their own favorite jokes and to retell jokes an examiner had just told them. In these tasks, the patients did fairly well, but they occasio~ialIymisordered or omitted key elements. Patients' difficulties in this highly constrained humor çetting suggested a link between their humor production and deficits observed in the production of non-humorous narratives (Gardner et al., 1983). Thus, narrative or cognitive problerns of a general nature seem to affect humor ouQ~t, which argues for viewing hurnor competence as a product of several component abilities that also figure in other, less affectively laden domains (Brownell and Gardner, 1988). However, they point out that localization of these functions to the right hemisphere is difficult to assess because the linpuistic demands of the tasks make testing left hemisphere damaged aphasic patients impractical. Timing in terms of when the huniorous matenal is introduced in a situation is equally impofiant in hurnor appreciation. Patients with fiontal lobe damage appear to have difficulty evaluating which places or what times are appropriate for humor expression. This is reflected in the number of clinical reports available which descnbe inappropriate joking and laughing in patients with fiontal lesions. Vardi et al. (1994) reported a patient with perseverative joking in the hospital ward, which appeared to be triggered by a variety of environmental stimuli. (These are described in more detail in a later section). In studies of humor expression, the emphasis has not been on cognitive processes but on incidental observations related to specific brain regions. In virtually dl, the right hemisphere is implied. Humor expression is afEected by brain dysfunction, the predominant brain area involved being the nght hemisphere. Sackeim et al. (1982) found that nght hernisphere damage was associated with nequent spontaneous outbmts of laughter. Sedation of the right hemisphere with sodium amytal produced increased laughter (Perxia et al., 196 1; Terzian, 1964). An important caution to remember is that laughter does not provide a clear index of the extent of underlying humor being experienced by the individual and generally shows only a moderate positive 3 1 relationship between funnlliess ratings given by the same person (McGhee, 1983). It is also highly susceptible to social context (Chapman, 1983). In Gardner et al. (1975) study, however. where laughter observed was clearly in response to humor stimuli, right hemisphere patients showed much more variability in their laughter, either showing extremely hi& amounts of laughter throughout or not at all. Increased eequency of joking has also been found among right hemisphere patients (Gainotti, 1972). Pema, Rosadini, and Rossi (1961) and Terzian (1964) found that sedation of the nght hemisphere produced increased joking. Clinical reports, however, suggest that the jokes that right hemisphere patients do tell tend to be inappropriate and to be told ar inappropriate times (Gardner, 1975)- Reviewing these studies, McGhee (1983) suggested that right hemisphere damage may be more dismptive to the joking component of one's sense of humor than damage to the ieft.

To summarize, production of humor and the cognitive processes required tbr successful humor expression have not been extensiveiy investigated in the neuropsychological literature. C hical observations and preliminary evidence to date have implicated the right hemisphere as having a special role not only in humor appreciation, but also in humor production. The majority of accounts of inappropnate hurnor production and expression suggest frontal lobe involvement. The present study examined humor in brai. darnaged patients with the hypothesis that frontal lobe damage is associated with impairments in both the appreciation and the prùduction of humor.

4. Frontal Lobe and Hurnor Key features required for humor to be effective are that it must be appropriate, timely, and tastefil. A disorder of these features is ofien seen as a result of fiontal lobe lesions. An association between fiontal lobe damage and a disorder of humor and laughter has been one of the most striking features reported in many histonc accounts of personality and emotional changes which occur as a result of fiontal lesions. Many clinical reports are available of patients in whom humor and laughter are highly exaggerated and are expressed at inappropnate times and places. These abnormal behaviors have been termed mona (stupidity/silly, euphoric behavior) and Witzelsucht (addiction to jokingkendency to tell inappropnate jokes). The following historie accounts of these reports is excerpted fiom Benton (1991). Three influential contributions in the late 1880s described the features of what has corne to be known as the "fiontal lobe syndrome". 32 Jastrowitz (1888) described a specific form of dementia in patients with &ontal lobe tumors. characterized by a lack of concern and an inappropriate or oddiy cheerful agitation, which he termed "so-called moria". Welt (1888) similarly reported personality changes in a patient with kontal injuries, which included a tendency to make bad jokes. He teased other patients unmercifully and played mean tricks on the hospital personnel. He showed no respect for the physicians and threatened to "expose" them in the daily press. His behavior, which becarne increasingly intoierable, was the subject of ahnost daily cornplaints by the hospital personnel. Welt, analyzing several cases with personality changes following fkontal damage, found that orbital and mesial regions of the prefiontal areas were implicated. Oppenheim (1WO), writing about frontal lobe neoplasms, called attention to "a psychic anomaly which is perhaps of focal diagnostic value". He described it as a peculiar addiction or compulsion to trivial joking of a predominantly sarcastic or latently hostile nature that was in sharp contrast to the patient's prevailing mood. Based on Jastrowitz's fiontal lobe localization of similar cases. he reviewed his own patients and confirmed it. Four patients who exhibited Witzelsucht proved to have tumors of the right frontal lobe, three of which had invaded the mesial and basal area. The studies of Jastrowitz, Welt, and Oppenheim cm be credited as outlining the distinctive changes in personality and behavior that occur as a result of fiontal lobe pathology. Commenting on these early papers, Benton (1991) noted that although this early assemblage of behaviors was observed for the most part in patients with tumor of the fi-ontal lobes, ail three clinicians rnaintained that they could occur in other conditions involving fiontal lobe pathology such as general paresis and trauma. Bilateral disease seemed to be the rule but this point was not emphasized. Instead the observation was made that involvement of the mesid-orbital area of the right fiontal lobe might be of particular importance in the production of the symptoms. Since these historic clinical reports were published, more descriptions have strengthened the relation between frontal lobe darnage and a disorder of humor. Zacher (1901), Schuster (1902), Bernhardt and Borchardt (1909), and Feuchtwanger (1923) made fùxther observations relating symptoms such as addiction to joking, childishness, moria, and Witzelsucht to fkontal lobe disease. Bernhardt aiso noted that patients with right fiontal involvement showed these features more frequently than did those with left frontal disease. Thus, in the early part of the century, a distinctive set of behavior deficits were being confïrmed as sequelae to prefrontal darnage and were included under the term "&ontal lobe syndrome". Although the syndrome cornprised a diverse set of behavior deficits including personality, affective and cognitive changes, an impaired sense of 33 humor (moria and Witzelsucht) was an ofien-mentioned symptom. Benton (1991) noted that a number of observers related personality changes specifically to orbital-mesial injury, and a few raised the question of whether right hemisphere involvement might be a particularly important factor. The speculation since the late 19th century that Witzelsucht and mona might be more representative of right fkontal disease has received Mersupport fkom recent reports. Bogousslavsky et al. (1988) reported a patient with a nght thaiamic infarct, whose main disturbance was a disinhibition syndrome mainly affecting speech, which rnimicked an acute manic delirium. Clhicai features included constaat smilùlg and inappropriate laughing, marked logorrhoea with constant switch fkom one idea to another, inappropriate cornments, extraordinary confabulations, and inappropriate joking. On neuropsychological testing the patient showed difficulty in performing conflicting tasks and inhibiting automatic responses in the Wisconsin Card Sorting, Stroop and Luria tests suggesting fi-ontal lobe dysfûnction. These neuropsychological Mpainnents correlated with the Gnding on Single photon ernission computerized tomography (SPECT) of a marked hypoperfusion not only in the nght thalamic region, but aiso in the overlying hemispliere predominantly in the fiontal region. Authors suggest that the behavioral syndrome was produced by disconnecting the dorsornedian nucleus fiom the frontal lobe and lirnbic system. Vardi et al. (1994) published a case report of a neurological patient whose behavior on the ward included inappropriate laughter and a ritual repertoire of puns and jokes. These repetitive behaviors continued unabated throughout his hospitalization. The perseverative joking repertoire was generally elicited by such environmental stimuli as physician's rounds, blood sarnpling, or holiday leave. From the patient's perspective, this type of humor was a normal style of speech. The patient remained nondiscnminating toward his jokes or puns, their context, and their impression upon the audience. The patient hirnself never laughed at his jokes. He was indifferent to the self-deprecatory portraits of himself. In addition, he did not react to jokes told by others and was insensitive to their humor. SPECT revealed hypoperfusion in the nght fiontoparietal area in the absence of structural darnage. The clinical description of this patient suggests that joke telling (humor production) could in some cases, becorne dissociated fiom humor appreciation and comprehension as a result of right fiontal lesion. As these reports indicate, impairments in the production of humor have been observed in patients with fkontal lobe lesions, particularly in those with nght frontal darnage. Studies of humor appreciation and production reviewed earlier implicate the right hemisphere. There has been no 34 study to date aimed specifically at answering the question of locus of humor appreciation and production within the right hemisphere, although the relationship of humor to the frontal lobe has been hypothesized. While sample sizes were too small to be conclusive, Gardner (198 1) and Wapner et al. (1981) found observed deficits in hurnor comprehension rnost common among patients with large lesions in the frontal areas of the right hernisphere. Bihrle et al. (1986) speculated on the role of the frontal lobe in narrative humor comprehension and suggested that damage to the frontal lobe irrespective of side may result in several cognitive deficits, including those reported in the Brownell et al. (1986) study, narnely, the attraction of right hemisphere patients to non sequitur endings and their difficulty in integrating content across parts of a narrative. Bihrle et al. (1986) therefore investigated this hypothesis in their study. They found that first, the right and lefi antenor subgroups made fewer rather than more total errors than did the corresponding postenor subgroups. Also, the left hemisphere damaged anterior subgroup made fewer total errors than did either of the right hemisphere damaged groups. Second, the nght hemisphere group error pattern (Le., more errors on non sequitur endings on the average than on straight forward endings and an attraction to hurnorous non sequitur endings in particular) provided a reasonable charactenzation of both the right anterior and right postenor subgroups' performances, but this error pattern was more rather than less applicable to the posterior subgroup's performance. That is, the lefi hemisphere damaged antenor subgroup did not show the charactenstic right hemisphere profile, and the nght hemisphere damaged posterior subgroup did. They concluded that their results provided no support for a special role for frontal lobe pathology in accounting for the observed humor deficits. In particular, damage to the anterior region of the lefi hemisphere was not sufficient for a humor deficit. However, they pointed out that given the small samples of anterior and postenor patients, their conclusions must be viewed with caution. While this study suggests that damage to the frontal lobes of the left hernisphere was not sufficient to produce hurnor deficits, it still leaves open the question of the role of the right fiontal lobe in rnediating humor. A review of the literature on £?ontal lobe fimctions provides evidence which supports the view that the fiontal lobe might provide the anatomical bais of humor. This evidence stems mainly fkom research relating lesions in the fiontal lobe to changes in language, personality, emotions, and self- reflective awareness. The fiontal lobes are also important in mediaticg several of the processes that are essential for normal appreciation and production of humor, such as problem solving, working memory, cognitive flexibility, abstraction, and visual directed attention. The evidence showing this is reviewed next. 4(a). Lanwa-ge The role of the £?ontal lobes in humor, especially in the appreciation and comprehension of jokes, cm be related to its role in language/communication. Alexander, Benson, and Stuss (1989) provide a detailed analysis of language and communication deficits after focal brain lesions involving the frontal lobes. Their evidence suggests that the ftontal lobes play an important role in discourse - how narrative language is generated, how narrative themes and content are selected, how connectedness and relevance are maintained in the narrative by the application of attention and self-critical observation, how abstracthonliteral language is generated and appreciated, and how indirect forrns of communication (sarcasrn, irony, affective intonation, and the like) are utilized. The role of the frontal lobes in discourse would provide an important link to its role in the appreciation of hurnor, since the features of discourse described above are necessary for successful humor appreciation. Lesions in different areas with the ffontal lobes result in different language deficits (reviewed by Alexander, Benson, and Stuss, 1989). Those related to humor, especially in terms of narrative cm be surnmarized as follows. Patients with large left media1 frontal lesions that include or undercut the SMA show impairments in manipulative language usage (e.g., explaining metaphors, interpreting proverbs, and arranging sentences). They show impaired narrative organization or great difficulty in producing any narrative. Neurobehavioral disturbances such as personality changes are also seen. Lefi anterior fiontal lesions result in a communication disorder involving formulation and deficits in reasoning, behavior, and affect that characterize the "fiontal lobe syndrome", producing an output lacking in tact and social propriety, Le., a "verbal dysdeconun". Thus, lesions within certain fiontal regions in the left hemisphere produced disturbances in the formulation of ianguage and in the more cornplex uses of language, i.e., abstract, complex, conceptual associations between verbal stimuli. Lesions within some regions of the frontal lobes in the nght hemisphere also produce language/cornmunicatim disorders. Right frontal lesions often produce affective motor dysprosody, as well as abnormalities in other aspects of verbal communication. For instance, patients with postenor right fiontal cortical darnage may formulate clear intentions of anger, sarcasm, etc., but cannot produce the speech contours needed to reflect those intonations. There may be disruptions in affective or pragmatic intent, and attempts at hurnor or sarcasm appear inappropriate or awkward. Such patients show difficulty in comprehension in several 3 6 paralinguistic domains: nonliteral verbal hurnor (Brownell et al., 1983); indirect requests (Brownell et al., 1986); sarcasm (Weyhan et al., 1988), and affect (Cicone et al., 1980). Alexander, Benson and Stuss (1989) report poor comprehension of cartoons, sarcasm, and indirect requests in a patient with right posterior frontal lesions. These deficits suggested disruption in two hctional systems - motor (affective dysprosody) and cognition (irnpaired pragrnatics) - that affect communication. Nurnerous investigators have thus highlighted the nature and range of deficits in the pragrnatics of discourse content (sarcasm, irony, inference) afler right hemisphere lesions. Aiexander, Benson and Stuss (1989) suggest that, although as yet no compelling evidence exists that proves that any of these deficits reflects darnage to any one region of the right hemisphere, they have been most commonly described following central (simultaneous frontal and panetal) damage or fiontal darnage. Social appropriateness, narrative coherence, and veracity may also be most severely damaged following right prefrontal damage. Limitations in the pragrnatic aspects of communication are found to be more marked in patients with large right dorsolateral frontal lesions, most prominently as a difficulty in organizing coherent narrative (Delis et al., 1983; Joanette et al., 1986). Tangential, irrelevant cornrnents are fiequent and a vague, rambling quality characterizes their verbal communication (Weylman et al., 1988). Alexander, Benson and Stuss (1989) report a reduced ability to make use of analogy, irony, and the like in patients with dorsolateral fiontal lesions. Another deficit in the logical narrative of patients with language disorder concemed the realm of inference (Brownell et al., 1986; Foldi, 1987).

Recognition that IWO statements, not immediately related, can be placed in a series to produce an inferred relationship was found to be disturbed in patients with nght frontal lesions. Another factor, far removed from basic linguistics, is also suggested by Alexander, Benson and Stuss (1989) to play a role in the quality of discourse fier right hemisphere lesions - a disturbance in social judgment (Luria, 1973; Weinstein & Kahn, 1955). These patients often show a production of an unpleasant humor with mocking self-references that may be distressing to family and fiiends. In severe cases, inattention to the communication context, blunted social awareness, loss of monitoring of the utterance's effect on the Iistener, and the piecemeal, tangential verbal style produce an apparently confabulated content of the narrative, even in the absence of any memory defect (Weinstein & Kahn, 1955). Right anterior kontal lesions may produce impairments in appreciation of social context. These patients show a strong tendency to respond directly with their fist association, perseveration is prominent and a confabulated, 37 disorganized content in narrative discourse has been reported (Alexander & Freedman. 1984; Stuss et al., 1978; Moscovitch, 1989). Thus, the right frontal ianguage/communication function may involve the set of cognitive activities which includes the capacity to utilize indirect and iderential mechanisms of discourse and the capacity to establish the relevancy of items within a narrative. The cortical representation for this functional activity rnay center on the dorsal lateral convexity of the right frontal lobe, though lateral, parietal and temporal association cortical areas may also be involved. Damage to this cognitive operation produces a complex distubance in inferential reasoning, in communicating irnplicit affective intentions, and in maintaining a coherent, direct point in narrative (Brownell et al., 1986; Joanette et al., 1986; Ross & Mesu~am,1979). Alexander, Benson and Stuss (1989) also suggest that the right fiontal lobes may be involved in an activity that provides a fiamework of formulation for communication. The activity consists of self control, the social interactional constraints that serve to guide communication efforts. The cortical representation for this activity is a broad area of the right prefiontal region; the anatornical substrate also includes the prefiontal projections to the more posterior fiontal lobe and to subcortical structures. Damage produces a disturbance in establishing and maintaining context for communication. Deficits include problems in anticipation, goal selection, and self- monitoring but are related to nonverbal information. The clinical manifestations are tangentiality, unanticipated changes in topic, socially inappropnate discourse and humor, and in severe cases, fiankly confabulatory or delusional context in a clear sensonum. As many of these problems are manifested through verbal output, a state of "verbal dysdecorurn" rnay be prorninent. Further evidence that the fiontal lobes are involved in pragmatic language skills is available fiom investigations of patients with closed head injury (CHI) which fiequently results in fiontal lobe darnage. McDonald & Van Sommers (1993) argued that comprehension and production of socially appropriate language where contextual cues are critical, require inferential reasoning, problem solving, and behavioral regulation, which are frontally mediated. Therefore, frontal lobe patients, though they perform normally on conventional language batteries which test language in a highly formalized and stnictured manner, wouId demonstrate disorders in communication only on tasks that are sufficiently challenging of executive processes. Using tasks similar to those employed with RHD patients, McDonald (1993), McDonald & Van Sommers (1993) found impairments in certain pragmatic language skills in 2 CKI patients. 38 On neuropsychological testing, both patients had no deficits on standard language testing for aphasia but demonstrated impairment indicative of fkontal darnage and impaired executive control, such as poor abstraction, disinhibition, inflexibility, impaired error utilization and monitoring of behavior. On tests investigating the ability to make requests in social contexts and producing off-the-record requests or hints (McDonald & Van Sommers, 1993). the two participants showed preserved capacity to evaluate a hypothetical social context and generate appropriate requests using politeness mechanisms, when the request was simple, conventional and straightfonvard, and opportunity to utilize old, well-established routines was present. In contrast, they had difficulty producing huits and executing them to cornpletion, where the requirement was that the message rnust not state its purpose literally. Authors suggest that routine and simple social interactions may be dealt with fairly automatically by these patients. However, poor performance on the language tasks used in the study suggest that cognitive deficits associated with impaired problem-solving ability and poor behavioral control cm also disrupt normal social communication skills, since they require the context to be considered cntically, balance competing priorities in the formulation of the message, and rnonitor speaker response. Thus, in the context of formulating a socially acceptable utterance. they demonstrated impaired conceptualization, failed to prioritize uiformation appropriately, and were unable to regulate their output. The CHI patients have also been shown to dernonstrate impairments on other pragrnatic and discourse tasks, such as the comprehension and detection of sarcasm (McDonald, 1992). The frontal lobe deficits in planning, monitoring, and impulse control also cause impairments in language production in these patients (McDonald, 1993). In a task which required these patients to describe a novel procedure to a blind-folded person, their discourse was characterized as being overly repetitive or providing too little detail. Their explanations were confising and disorganized, they used unexplained references, focused on inappropriate tangents, and made sequencing errors, failing to present information in the same order of priority as did the controls. Again, the discourse errors exhibited by these CHI patients were a direct reflection of their fiontal lobe deficits of concreteness, poor impulse control and impaired planning, regdation and monitoring or behavior. The role of the frontal lobes in language, particulady in manipulative language use and the complex uses of language, provides evidence of its involvement in hurnor. The language and communication impairments following fiontal lobe Iesions parailel disturbances in personality and emotions that are also a consequence of fiontal damage.

403). Personalitv and Emotion A strong association between frontal lobe darnage and alterations in personality and emotions has been recopnized since the descriptions of Phineas Gage (Harlow, 1868). Despite good physical recovery and many preserved cognitive abilities, his emotional behavior and personality were so significantly altered that his fEends stated that he was a different person: "No longer Gage" (Stuss, Gow, & Hetherington? 1992). Since then, most accounts of observations of patients with frontal lobe pathology have included certain charactenstic changes in personality and behavior. Of the long listing of changes in personality, emotions, and behavior observed foliowing frontal lobe injury, those that might be related to humor processes are reported here. Lishan (1968) summarized a number of studies and suggested a behavioraI syndrome based on frontal damage that he descnbed as "including one or more of the following symptoms in severe degrees: lack of judgment, reliability, or foresight; facetiousness; childish behavior; disinhibition; and euphoria". Shiss et aL(1992) reviewed the changes in personality and emotion that occur after damage to the fiontal systems. Among the changes in personality and emotions that follow frontal lobe damage they listed altered mood (exaltation or depression), decreased concern with social propriety, apathy and indifference, depression, automaticity, incontinence, restlessness, exuberance, euphoria, witzelsucht, despontaneity (meaning a notable decrease in initiative, disorders in thinking, and emotional control), lack of judgment, diminished reliability or foresight, facetiousness, childish behavior, disinhibition, anxiety, social withdrawal, outbursts of irritability, decreased empathy, inertia, lack of ambition, indifference to opinions of others, poor judgment, satisfaction with inferior performance, extroversion, lack of restraint, purposelessness, decreased interest and drive, slowness in thinking, decreased self-concern, shallow affect, depressed outwardly directed behavior and social sense, lethargy, impulsivity, distractibility, egocentricity, and grandiosity. They stressed the heterogeneity of symptorns and suggested that these changes can be best understood as specific disturbances in drive, mood, affect, or personality (including self-reflective awareness). The ability to judge emotional situations correctly is necessary for appropnate emotional and social responses, and both lefi and right fiontal and temporal regions are hypothesized to be involved in judgment of emotional situations and selection of appropriate responses (Kolb and Taylor, 1988; Stuss and Benson, 1983). Relating fiontal lobe lesions to personality, Stuss et al. 40 (1992) noted that selective darnage to the frontal lobe changes the stable responses to the environment. Although more modula fùnctions may be intact, the appropriate and timely implementation of these may be impaired. Frontal lobes play an important role in monitoring of behavior and fiontal lesions also result in a failure to be self-cntical. The ability to expenence emotion, however, can become disconnected 6rorn the ability to express emotion in certain instances. For instance, in pseudobulbar palsy. there is an overflow of emotional expression not directly reflecting the individual's mood (Lieberman and Benson, 1977). Disordered expression of affect such as excessive crying or laughing in reaction to seemingly trivial environmental events and emotional expression incongruent with actual feelings and emotional context can occur as a result of fiontal system lesions (Stuss et al., 1992)- Damasio (1994) has accorded the fiontal lobe a crucial role in the development of personality and a sense of self (described in more detail later in the section on self-awareness and the fiontal lobes). Stuss and Benson (1983) indicated that although personality changes have long been accepted as good indicators of fiontal lobe involvement, to date, this is limited to clinical observations and there is an obvious need for quantified investigation of fiontal personality disturbances. In a similar vein Ross (1997) noted that although dramatic changes in emotional behavior and personality have been well docurnented following prefrontal brain injury, an active role for ernotional processing as a core part of fkontaI lobe functions has been Iacking. Damasio (1994) has been exploring this issue and suggests that emotions are essential for guiding and driving prefiontal behavioral functions by ensuring that actions based on logical premises and rational reasoning are, in fact, appropriate to the social and situational context. Ross ( 1997) has suggested that the prefbntal cortices have a pre-eminent role in the modulation of emotional intelligence, the ability to read, interpret and respond appropriately to the moods, needs, and behavior of others, to regulate one's own emotions and behavior, and to use emotions effectively to motivate, plan, and achieve goals. The personality and emotional changes associated with frontal lobe lesions bear a striking similarity to those reported following right hemisphere lesions. For instance, Brownell and Gardner, (1988) in discussing neuropsychological insights into humor, report that right hemisphere patients show poor judgment and insight into their problems; routinely their discourse and actions are socially inappropriate. They also noted that "clinical observation suggests that it is the right hemisphere which is especially relevant to hurnor cornpetence, since 4; one does not routinely see the same gamilous, socially inappropriate behaviors in patients with unilateral left hemisphere damage". Moreover, right hemisphere patients are not infrequently witîy or metaphoric (Weinstein and Kahn, 1955) but these characteristics emerge with undue fiequency in situations where they are manifestly inappropnate. In talking to a right hemisphere patient, one often has the sense that the brain damage has altered his / her personality. Change in personality is also the most noticeable feature of patients consequent to frontal lobe damage and is charactenzed by lack of judgment and insight, lack of inhibition, and socially inappropriate behavior, such as a tendency to tell inappropnate jokes. Sirnilarly, as was noted earlier, Gardner et al. (1975) suggested that deficits in humor comprehension in right hernisphere patients are consistent with the view that the right hemisphere may be important for the production of emotionally appropriate responses. The fiontal lobe is hypothesized to be necessary for judgment of emotional situations and selection of appropriate responses. For instance, Stuss and Benson (1983) observed a dissociation of perceptual and cognitive awareness in leukotomized (fiontally damaged) patients which could be considered a cognitive defect of emotion. One aspect of reported personality disturbance following prefiontal damage appeared to be an inability to transiate mood or emotion into appropriate behavior. The personality in these patients appeared to be a discomected phenornenon with the emotional behavior separated from the environment. Nauta (1971) suggested that information kom the external environment gathered through al1 modalities, both exteroceptive and interoceptive, converge only in the fkontal lobe. Testing of the affective consequences of a chosen behavior and choosing between alternative modes of thought and action would thus appear to be fiontal functions. Darnage to this "anticipatory selection process" may underlie some of the behavioral changes of frontal impairment such as flatness of affect, instability of intent, loss of ability to foresee the outcome of an action, and socially inappropriate behavior. In tems of humor production, as Brownell and Gardner (1988) suggest, one component of successful humor production involves howing when and where to tell a joke and this sense of when it is permissible to Say something involves judgment, the ability to inhibit oneself, and a degree of empathy. Clinical profile suggests that right, but not lefi-sided pathology grossly alters a patient's sense of what is appropriate and nght hemisphere damaged patients are prone to making msensitive statements which can seem funny in certain situations. A sense of socid perspective and empathy seems to be missing in right hemisphere damaged patients. As 42 reviewed earlier, this same profile of changes in personality reflecting lack of judgment and insight, and sociaily inappropriate behavior is a prominent feature in patients with frontal lobe lesions.

To summarize, damage to the frontal lobes produces a similar profile of changes in langage, personality, and emotion as that observed after iight hemisphere darnage. It appears likely that the locus of this right hernisphere deficit could lie within the fiontal lobe. An impairment in humor appreciation and production might be a feature of these deficits in fiontal lobe patients. Ln addition to probiems with language? personality, and emotion resulting fiom damage to the fiontal lobe, other functions mediated by the fiontal lobe, such as problem solving, working rnemory, cognitive flexibility, abstraction, and directed visual attention are also essential for humor.

5. Humor and Functions Mediated bv the Frontal Lobe The involvement of the frontal lobes in humor is also suggested by some of the cognitive processes necessary for hurnor comprehension and which are also hypothesized to be frontally mediated functions. The understanding of hurnor entails a problem solving process, requiring the successful application of several cognitive processes. These include problem sotving, working memory, cognitive flexibility, abstraction, directing and sustainhg of attention, visual search, and scanning. The contribution of these processes to humor comprehension has not been investigated in previous research. The present study will address this issue by administering tests designeci to assess each of these cognitive processes and correlating performance on these tests with that of specific humor tasks.

Xa). Problem Solving Problem solving, especiaIIy in noveI, nonroutine situations has been generally regarded as a fûnction mediated by the fiontal lobe. The problem solving functions of the fiontal lobe would be important in the comprehension of huniorous material suice hurnor often involves the application of nonroutine solutions or interpretations to the understanding of the situation in which humor occurs. 4 3 Problem solving has been seen to play a prominent role in the comprehension of hurnor. Shultz (1976) and Suls (1972) who proposed the rnost widely accepted cognitive model of hurnor, the Incongruity - Resolution model, have analyzed the appreciation of jokes as a problem solving process. Suls (1972) used an information - processing type of analysis to introduce his model of the humor appreciation process. He suggested that a joke or cartoon is found to be fûnny as the result of a two-stage process. In the first stage, the perceiver fmds his expectations about the text disconfirmed by the endhg of the joke or, in the case of a cartoon, the expectations about the picture disconfimed by the caption. Ln other words, the recipient encounters an incongnùty - the punch line. In the second stage, the perceiver engages in a form of problem solving to find a cognitive rule which makes the punch hefollow from the main part of the joke and reconciles the incongnious parts. Further, Suls (1972) states the problem at stage 2 as follows: How does the punch line (B) follow from the preceding parts of the joke (or the cartoon picture) (A)? With the problem fkarned in this manner, the main part of the joke comprises the premises of the problem and the punch line the end product. The task of the problem solving is to find out how the punch line follows or is congruent with the preceding text. Suls (1972) conceives the problem solving process in the second stage as worhg along the lines of the GPS developed by Newell et al. (1958), which was designed to represent and explain the process and goal-directed nature of human problem solving. As in the GPS, in the problem solving in joke resolution, the recipient attempts to transfom the jokefs A into B by conparing the two to identiQ differences and then establishing a subgoal to reduce these differences. That is, the major goal of problem solving in joke resolution is to transform A into B and this requires means-end analysis, establishment of subgoals, and transformation or operations to reduce differences between A and B. The operators are cognitive rules which, when applied to A, will produce a new expression less different fiom B than the original A. These niles are semantic, logical, or experiential. When the rule (or operator) is found, it is applied. Then the new object and B are compared; if they do not match, the process continues until the proper rules are applied to obtain correspondence. When the process reaches correspondence, the individual has found how the punch line of the joke (B) follows fiom the main part (A). In the ideal case, the problem solving will be successful and will retneve the relevant mle that reconciles the joke parts. The punch line is then perceived to make sense, and the person "gets" the joke. When the apparent incongnllty has been made congruous, the program has succeeded and will terminate; the humor has been understood. Thus, problem 4 4 solving is an essential part of the hurnor appreciation process. Similar theones have been suggested to explain the processing of irony which also entails a juxtaposition of incompatibles - what is said (literal meaning) versus what is intended (nonliteral or figurative rneaning)(Lucariello (1 994). Lucariel10 (1994) suggests two possible routes for the processing of ironic events. First, if processing were serial, script laiowledge, that is, knowledge of what was expected to happen. would be activated when events are first expenenced. If script-based expectations were violated, then knowledge of nonprescriptive events, such as ironic ones, would be activated to interpret the expenence. This processing path is similar to that proposed for interpreting nonliteral language, such as metaphor and verbal irony (Grice, 1975, 1978; Searle, 1975, 1979). Here, the confkontation of literal meaning is proposed to be a necessary step in the path to comprehending speakers' utterances. Only when literal meaning is inconsistent with the context does the hearer seek an alternative, or nonliteral (ironic), meaning. This processing of ironic events is sùni1a.r to what is proposed to occur in processing humor. the senal processing model (Long and Graesser, 1988). Senal processing presumes that literal meaning is processed first, and that alternative, figurative meaning is constnicted only when there is a discrepancy between the punch line and the preceding context. For example, Raskin (1984) proposed that a joke begins with the presentation of a text consistent with one script. Second, a script-switch trigger (e-g., the punch line) is presented that is inconsistent with the currently evoked script. This provokes the listener to search for an alternative script with which the text is compatible. Hurnor results ffom the overlap of scripts. These theories are similar to the two-stage processing model for humor proposed by Suls (1972) and likely to involve the same problem-solving analyses required for processing of humor stimuli. The alternative processing route is when both script laiowledge (knowledge of what was expected to happen) and ironic event knowledge (knowledge of what actually happened) are accessed when a person experiences events. An ironic judgment is made - that is, the ironic schema is activated - if the script structure does not account for the expenence at hand and the ironic event schema does. This route is sirnilar to the parallel-race processing path proposed for humor (Long and Graesser, 1988). In this model, both literal and alternate literate or figurative text meanings are accessed. A humor judgment is made if Meaning 2 of a word or phrase makes sense given the preceding text and Meaning 1 does not. 4 5 The above analysis regarding the processing of nonliteral language such as irony and metaphors shows their similarity with the processing of humor. Understanding of irony and metaphors also requires the type of problem-solving processes proposed for hurnor. The processes comprising the problem solving analysis of humor (as well as nonliteral langage such as irony and metaphor) can also be related to fkontal lobe mediated functions. Darnage to the frontal lobes are generally considered to produce difficulties on specific problem-solving tasks or in dealing with certain types of practical problems that occur in everyday life. Behaviors which are exhibited in novel or demanding situations have been Iabeled 'ffontal lobe functions'. The problem-solving fimctions play a central role in theories and models developed to explain and understand frontal lobe functions and have been referred to under such tenns as 'executive functions' (Stuss and Benson, 1986; 1990), 'supervisory system' (Norman and Shallice, 1986; Shallice and Burgess, 1991), and the 'dysexecutive syndrome' (Baddeley and Wilson, 1988). Stuss and Benson (1986; 1990) proposed a hierarchical model of brain organization that emphasized the role of the frontal lobes. Three levels of fiontal lobe functions were proposed, the first involving sequencing and drive. The second level of frontal lobe functioning was termed executive function and included anticipation, goal selection, preplanning (means-end establishment), monitoring, and use of feedback. These are problem solving fùnctions and the fiontal lobes were considered to play no active role in routine, overleamed situations, but were essential only in novel andor complex situations. The Norman and Shallice mode1 (1986; Shallice and Burgess, 1991) was based on artificial intelligence models of problem solving such as that of Newell and Simon (1972). Damage to the Supervisory Attentional System (SAS) in this model corresponds to fiontal lobe damage. The SAS was held to be required in situations involving planning or decision-making, error correction or troubleshooting, where responses are not well leamed or contain novel sequences of actions, are dangerous or technically difficult, or require the overcoming of strong habitua1 responses or resisting temptation. That is, fkontal lobe patients with damage to the SAS should have difficulties in problem situations involving nonroutine or novel procedures. The problern soiving function of the fiontal lobes has particular relevance to the comprehension of humor. The appreciation of humor has been considered a problem solving process requirhg the ability to resolve incongniities. In a joke, when incongmity is detected in a punchline, this is a novel, nonroutine ending to the story. The listener then engages in a problem solving process, Le., searches for the interpretation that reconciles the incongmity and checks to see if this new 4 6 interpretation resolves the incongmity satisfactonly. This process is similar to the processes described as executive function and the SAS in earlier models. Patients with frontal lobe pathology can therefore be expected to show impairment in hurnor tasks as a result of their problem solving deficits. Some of the frontal cognitive processes required for efficient and successful problem- solving are working memory, cognitive flexibility, and abstractability, al1 of which are important to humor.

5(b). Workine Memorv There has been considerable interest in working memory as a fkontally mediated function in recent years. Workuig mernory commoniy refers to the temporary holding of infoxmation that is currently being processed. The appreciation of humor also requires this ability. Short term memory has been conceptualized as a set of separate but interacting subsystems. These components, called working memory, rnay be coordinated by a central executive system related to the fiontal lobe which is responsible for the selection and operation of control processes and strategies (Baddeley, 1986). Patients with frontal lobe darnage are reported to perform poorly on tasks that are thought to reflect the functioning of working memory (Baddeley & Wilson, 1988).

The brain's working memory function, i.e., the ability to bring to mind information and hold it 'on-line' in the absence of direct stimulation, has been suggested as being its most flexible rnechanism and its evolutionarily most significant achievement (Goldrnan-Rakic & Friedman, 1991). These investigators have shown that the dorsoIatera1 prefkontal cortex (principal sulcus and its connections) are involved in delayed response and delayed altemation tests, which are seen to require working memory, Le., constant updating of uiformation. Recent data using PET imaging have Mersupported the role of the frontal lobe in working mernory (reviewed in Buckner and Tulving, 1995). The verbal working memory tasks generally activated left prefkontal areas whereas the spatial working memory tasks included bilateral activation with right-sided activation being more prominent. A role for working memory in the understanding of humorous matenal would be logical since this is a function mediated by the frontal lobe and can be viewed in relation to its problem solving hctions. For instance, Baddeky (1986; Baddeley and Wilson, 1988) has identified the SAS proposed by the Shallice mode1 with the Central Executive component of working memory and has suggested the term 'Dysexecutive Syndrome' as a functional characterization of patients with 47 frontal lobe damage. Moscovitch (1989, 1992) (also, Moscovitch and Winocur, (1992a); Moscovitch and Winocur. (1992b); Moscovitch and Umilta (1991) has described the frontal lobes as working memory or working-with-mernory structures that mediate the control processes related to memory. The frontal lobes are involved in organizational or strategic aspects of memory that are necessary for devising strategies at encoding, for guiding search at retrieval, for placing retrieved memories in their proper spatial and temporal contexts, and for using mnemonic information to direct thought and plan future actions. In other words, the fiontal lobe's function with respect to memory is seen to be consistent with its hctions in other domains. It organizes the raw matenal that is made available by other structures so that thought and behavior can be goal-directed. For instance, strategic processes. where problem-solving routines such as response selection and monitoring, need to be applied to memory, would require the kontal lobes. In hurnor, working memory can be applied to the Incongruity-Resolution model (Shultz, 1976; Suls, 1972) of humor comprehension. That is, during the resolution stage of the model, it would be essential to keep information presented in the body of the joke in working rnemory in order to assess the interpretations afforded by the punchline and monitor the match on-line until the punchline cm be seen to make sense at a different Ievel. Thus, the incongruity is resolved and humor is cornprehended. Brownell et al., (1983) indicated that a listener must be able to appreciate the relations arnong the elements in the body of the joke and keep them sufficiently in mind so that he cm attempt to relate them to the punch line to produce coherence. This is the function of working memory. Working memory would be important in the process of appreciating humor as outlined by McGhee (1983). He suggested that a given joke, cartoon, or spontaneous humorous incident requires simultaneous awareness of several key bits of information rep~esentedin the cuent stimulus event, along with pertinent context-related knowledge derived from past experience, and this is a function of the nght hemisphere. For instance, when the unexpected and incongruous information is delivered in the joke (the punchline), the left hemisphere appem unable to go beyond registering surprise. It is the nght hemisphere that cornes into play at this point and produces the simultaneous awareness of two meanings (as in a pun) or of diverse elements that must be brought together in order to appreciate the humor potentially present. Similarly, in nonverbal humor, a cartoon will not be understood until other information available fhm either the cartoon or the individuals's pnor experience is seen to provide a meaningful and 4 8 coherent link with the elements fomiing the incongruity. Again, this presurnabiy requires right hemisphere involvement..... simultaneous processing in the right hemisphere plays the most important role in the hurnorous insight. That is, at some level, the individual is aware of both the expected relationship and the current incongruous relationship at the sarne time (McGhee, 1983). Working memory can be seen to be cntical in achieving this hurnorous insight. That is. achievement of simultaneous awareness of two meanings or of diverse elements as McGhee (1983) suggested, would be impossible without working memory. Working memory would be required to keep a stimulus in rnind (e.g., the punch line) and simultaneously retrieve other relevant information (hmthe body of the joke or from the individual's persona1 expenence) until they can be matched and coherence is achieved. In order to 'get' the humor that is potentially present in a situation, therefore, at some level, the individual must be aware of both the expected relationship and the current incongruous relationship at the same tirne. This would not be possible without working memory and cognitive flexibility (discussed below). In the present study the relationship between working memory and joke comprehension was investigated. The Alpha Span test (Craik, personal communication) was used to assess working memory. Performance on this test was correlated with that on a Joke Cornpletion test in order to evaluate the contribution of working memory to joke comprehension.

Xc). Cognitive Flexibilitv Cognitive flexibility is a necessary component of problem solving. Once conûonted with a problem, its solution entails the ability to produce various alternatives that can be applied- This requires cognitive flexibility and would also be necessary for problem solving in humor. In the Norman and Shallice (1986; Shallice and Burgess, 1991) model, the SAS was held to be required in situations such as those involving planning and decision-making, when strong habitua1 responses need to be overcome, or in novel, nonroutine situations, when the routine lower levels of the system cannot solve whatever problem they have been presented. A major hction of the SAS therefore, is plan formulation or modification. In the Stuss and Benson (1986, 1990) model, similady, the executive functions of the fiontal lobe which involve goal selection and preplanning require cognitive flexibility. Producing a solution to a novel situation by the executive functions or the SAS requires the thinking up of alternatives that may not have been utilized earlier and perhaps applied in a novel way, i-e., cognitive flexibility. 4 9 Inflexibility, rigidity, or perseveration are reported to be particularly marked after lesions of the prefiontal regions (reviewed in Walsh, 1987). The Wisconsin Card Sorting Test (WCST) has been used widely to study 'abstractabilityy and 'shifi of set' and has been rnost cornrnonly used as an important indicator of frontal lobe dysfunction. Though its specificity regarding the identification of fiontal lobe pathology has been under question, Stuss et al. (1994) in their review, surnmarized that the WCST and other hypothesis sarnpling or shifting tests are fkequently, but not necessarily impaired afier &ontal lobe damage. They hrther concluded that deficient hypothesis formation. pian formulation, and shifting established response patterns are part of an impairment in cognitive executive abilities in patients with fiontal lobe lesions. A major component process required for problem solving leading to joke resolution appears ro be an ability to think in abstract terms, as well as flexibility in thinking, which allows one to choose fiom among the alternate interpretations or operations the correct one to make the punch line congruent with the body of the joke by revising the initial interpretation. This is the second stage outlined in the Incongruity-Resolution mode1 of humor cornprehension. Rigidity or inflexibility, i.e., the inability to think flexibly and shif? according to the demands of a situation, inability to consider the importance of relevant information for revising the initial interpretation, or a problem in integrating new information with previous knowledge have been proposed to explain RHD deficits in pragrnatic language and in hurnor (Bihrle et al., 1986; Brownell et al., 1986). Frontally damaged patients are also ofien reported to be concrete and literal in their interpretations. In addition, cognitive flexibility or shifting, monitoring and judgment of responses, and use of feedback are required to test whether the interpretation chosen for joke resolution is the nght one so that the problem has been solved satisfactorily and in a way that is congruent. Al1 of these processes are part of the "executive functions" widely believed to be mediated by the fiontal lobe. In the present study, (1) the Proverbs test, (2) the Wisconsin Card Sorting Test (WCST), and (3) Part B of the Trail Making Test, will be used to assess cognitive flexibility or shifting of set and abstraction, and their relevance to humor. (1) Proverbs test: Tests of interpretation of proverbs have been used widely for evaluating quality of thinking, i-e., in evaluating where the patient's thinking Lies on an abstract-concrete dimension, and abstract verbal reasoning (Lezak, 1983). (2) The WCST will be used to assess the subjects' ability to form abstract concepts, and shift and maintain a set. It is a novel, complex task requiring goal selection and hypothesis testing, along 50 with cognitive flexibility and the inhibition of salient responses. That is, it provides information on several aspects of problem-solving behavior (Heaton, 1981). Despite controversy regarding its specificity to frontal lobe pathology, in this study, it will be employed to evaluate cognitive flexibility and shifting and its relation to humor. (3) Part B of the Rail Making Test has been considered a test of mental flexibility or shifting course dunng an ongoing activity (Spreen and Strauss, 1991) and has been identified as beinj sensitive to prefi-ontal lesions (GoIden. 1981 ). In addition to problem solving, working memory, and cognitive flexibility, another function mediated by the frontal lobe, visual directed attention, is also essential to humor appreciation, particularly to nonverbal humor.

5(dl Visual Directed Attention The frontal lobes have been considered to play an important role in attentional functions. Stuss et al. (1 994), in their review of Crontal lobe functions suggested that studies on visual scanning, visual search, and control of eye movements are intimately related to the concept of directed visual attention. The review indicated that deficits in processes such as direction of attention to extrapersonal space, visual scanning, visual exploration/search, selective and sustained attention may be present following fiontal lobe pathology. In particular, the nght frontal regions were imp licated. The processes of visuai attention, scanning/search has particular relevance to cartoon humor. In a cartoon picture, particularly when no verbal cues are provided, the hurnor is often depicted by a detail in the drawing. This necessitates the direction of attention to the relevant, cntical detail. A visual search/scanning of the drawing is required in order to pick out the cntical detail and then focus on it before humor cm be comprehended. In the present study, the contribution of directed visual attention, scanning/visual search to the appreciation of cartoon hurnor was investigated. A cartoon test, the Cartoon Array task, was designed which provided minimal or total absence of verbal information. Only a critical visual detail present in the cartoon drawing depicted the hurnor present in the situation. The participants had to conduct a visual search and focus on the relevant humorous detail. Performance on this cartoon task was correlated with that on tests traditionally employed to assess visual scanning and attention. 5 1 Three tests were administered to assess visual scanning, search. and attention. 1. Trail Making Test: This test has been considered a test of speed for visual search, attention. mental flexibility / shifting course during an ongoing activity, and motor fünction (Spreen and Strauss, 1991); visual conceptual and visuonotor tracking (Lezak, 1983). Part B of the Trail Making Test has been identified as being sensitive to prefÏonta1 lesions (Golden, 1981; Pontius. 1973). In addition, successful performance on Part B, which requires alternating between Ietters and numbers, is likely to require working memory. 2. Letter Cancellation: This test assesses the capacity for sustained attention, accuracy of visual scanning, shifting of responses, and activation and inhibition of rapid responses (Lezak. 1983; Spreen and Strauss, 199 1). 3. Embedded Figures Test: This test has been used to examine visual search and tracing of a figure embedded in the background (Spreen and Strauss? 1991). On a similar test, the Hidden Figures test, patients who had surgery involving the fkontal cortex were reported to obtain significantly lower scores than other brain damaged patients (Teuber et al., 1951, as reported in Lezak, 1983). Performance on these three tasks were used as measures of visual directed attention, visual search, and scanning, and correlated with performance on the Cartoon Array task, in order to investigate how these processes relate to nonverbal humor comprehension.

In surnmary, certain functions mediated by the frontal lobe were investigated in relation to humor appreciation. These included problem solving, working memory, cognitive flexibility, abstraction, and directed visual attention. hnpaimients in these cognitive processes, in addition to deficits in language, personality, and emotion as a result of fiontal lobe darnage provide a compelling argument in support of viewing humor as a fiontal function. Humor deficits in patients with fiontal lobe damage are related to processes of metacognition and self-awareness, which are also fiontally mediated processes. The relationship of humor to metacognition and self-awareness is outlined in the next sections.

6. Metacopnition and Humor Metacognition or the ability to reflect upon and monitor one's own cognitive activities plays an important role in humor appreciation. This issue is particularly relevant when we evaluate our 52 responses to a humor stimulus. In the present study, metacognitive influences would have a significant influence on the funniness ratings provided by the participants for humor stimuli. It would also be cntical when the participants are asked to rate their own sense of humor. McGhee (1983) points out that metacognitive issues have not been addressed in the study of humor and that the central question concems how individuals use perceptions of their own arousal changes or Iaughter in making judgments about funniness. We might presume that providing a judgrnent or evaluation regarding how funny we perceive a humorous event to be, would be a complex process, influenced by several factors. It would require the ability to combine information hm several sources, such as physiological arousal, Iaughter, difficulty Ievel of the stimulus, content of the humorous stimulus, and resulting change in mood, among others. An evaluation needs to be made as to the proper weightage to be assigned to each of these pieces of information so that a balanced judgment may be arrived at while evaluating humorous stimuli and assigning funniness ratings. Motivation, attitudes, values and personality of the rater may be additional factors influencing rater response to hurnor stimuli. This is generally an unconscious process in that we do not often deliberately reflect on these factors in providing a rating. These issues have not been investigated in relation to hurnor. It is possible that the relative impact of each of the factors that influence ratings of funniness might be different for certain groups. For instance, Leventhal and Mace (1970) reported that females rated a slapstick film to be funnier when they laughed at it more. Metacognition is an important area of research in relation to fiontal lobe lesions given its function in evaluation, monitoring, planning, and decision making. Thus, a comparison of the funniness ratings, as well as a rating of their own sense of humor provided by fiontal lobe patients in comparison with those with nofiontal lesions and normal participants would throw light on the role of the fiontal lobe in metacognition and self-awareness/self-refiectiveness.

7. Self-Awareness and Humor Self-awareness, including self-reflectiveness and reality monitoring are fûnctions subserved by the fiontal system that would also be related to deficits in humor. That is, appreciation of humor entails a reflective appraisal of the situation or of the information in which hurnor is present. This requires the ability to use the individual's past experience and accumulated body of knowledge to interpret current experience. A sense of self or of persona1 continuity based on past experiences and persona1 mernories forms the basis for self-awareness \ self-reflectiveness. Lesions to the prekontal 53 regions of the brain or to frontal systems can cause altered behavior or disorder of personality that impIy disturbances of self and awareness. The terms 'consciousness' and 'self-awareness' have ofien been used interchangeably. WheeIer et al. (1997) consider consciousness a general capacity that an individual possesses for particular kinds of subjective experience, whereas awareness refers to a particular mani/statiori or erpression of this general capacity. Consciousness, like other capacities of living systems, has no object, it is not directed at anything. Awareness, on the other hand, always has an object, it is always of something. Thus, awareness presumes consciousness, but consciousness does not imply awareness; consciousness is a necessary but not a sufficient condition of awareness. Self-awareness has been defïed as "the rnomentary focus or direction of attention to one or more constituents of the self' (Stuss, 1991b). A disturbance in self-awareness, unconcern or lack of awareness regarding own behavioral changes or deficits, deficient self-monitoring, have been reported in patients with fiontal lobe lesions. Key processes of a sense of self are awareness (of self), monitoring (of the self s condition), and integrating experience across rime (into the sel0 (Stuss, 199 1b). Stuss & Benson (1986) in their hierarchical mode1 of brain hction regarded seif-awareness as the "highest" of al1 integrated brain activities. The final level of fbntal fimction was thought to be consciousness itself, the ability to be aware of oneself and the relation of self to the environment. Self-awareness, consciousness, self- reflectiveness was proposed to be intimately connected to the prefkontal regions, and utilizes and interacts with other brain processes in the overall goal of developing an aware individual interacting with the environment. In behavioural terms, a disorder of self-awareness would be revealed as unconcem, a dissociation between knowledge and use of that knowledge, absent or deficient monitoring of behavior, and imp aired self-regdation (Stuss, 199 1a). The disturbance of awareness following fiontal lobe injury is a general deficit in self-awareness and not a focal disturbance of awarenesç such as neglect. It has been suggested to be the result of a disconnection of intact worldly knowledge (e-g., intact language, attention, memory) controlled by postenor brain areas fiom frontal controlling / executive functions such as monitoring, assessing, and evaluating, which are impaired. That is, fkontal system unawareness is not lack of knowledge but impaired judgment of objective facts in relation to one's own life - a disturbance in self- awareness. There is a striking dissociation between correct knowledge, use of knowledge, or awareness of the implications of such knowledge. Thus, there is a deficit in self-reflectiveness, a dismption in the judgrnent of the implications of acquired knowledge (Stuss, 199lb). 54 Another feature of a disorder of self-awareness is a disturbance in the feeling of intimacy. immediacy and warmth with regard to one's memories and a lack of continuity between past and present memories in relation to decisions in the future (Stuss, 1991a). Frontal lobes play an important role in the temporal integration of behavior, which is cntical for the maintenance of self. In patients with fiontal lobe damage, there is a disturbance of subjective time, impaired contemplation of past and future events, and recall of these events (Stuss, 1991b). Persona1 memories are important in defining the self and Tulving (1989), using blood flow measurements. suggested that episodic memory or memory for personal events, is fkontal in localization. PET studies have fürther suggested that the right prefiontal regions may be particularly relevant during retrieval of episodic memories (Tulving et al., 1994). Therefore, fiontal lobe damage would lead to a sensation of dissociation of memones fiom the persona1 self, also a feature of disturbance in self- awareness. Wheeler et al. (1997) have elaborated the relations between the kontal lobes and autonoetic consciouçness and their particular relevance to episodic memory. Based on converging evidence fiom such diverse sources as brain imaging, neuropsycliological expenments, clinical observations, and comparative and developmental psychology, they concluded that there is a special relation between episodic rnemory and the prefrontal cortex which is mediated through autonoetic consciousness, the capacity to attend to one's own subjective experiences across time. A fully developed autonoetic consciousness is considered to be dependent upon the integrity of the fkontal lobes. Further, autonoetic consciousness~as mediated by the frontal lobe, is considered to be critical for episodic memory. Wheeler et al. (1997) argue that the prefrontal cortex, in conjunction with its reciprocal connections with other cortical and subcortical structures, empowers healthy, adult humans with autonoetic consciousness. The most complete expression of autonoetic consciousness, autonoetic awareness, occurs whenever one either consciously recollects, or 're-experiences' a happening fiom a specific time in the past, or attends directly to one's existence and conduct at a time in the future. Autonoetic awareness of the subjective past constitutes episodic retrieval. Large fiontal lobe lesions disturb the capacity for autonoetic consciousness. Features of a deficit in autonoetic consciousness include an inability to apply knowledge to oneself, inability to intemalize knowledge at a self-reflective, or personal level, and a dissociation between knowledge (and executive functions) and the realization of persona1 relevance of that howledge. 55 Disturbed self-awareness can produce drarnatic clinical conditions such as reduplicative paramnesia or Capgras syndrome, where the individual is subjectively convinced that a familiar place or person has been duplicated, as well as fantastic confabulations and delusions. Such cases represent a deficiency in monitoring at a supramodal level, an inability to self-monitor, to self- correct behavior, and to use feedback to change responses. This is not a disorder of awareness of factual knowledge, but the deficient feedback loop occurs at the level of executive control fiutions (Stuss et al., 1978; Alexander, Stuss, & Benson, 1979; Benson & Stuss, 1990; Stuss, 1991a.b). Patients with these conditions invariably dernonstrate fiontal lobe damage and the nght frontal region appears to be particularly relevant. Prigatano (1991) reports a perception of an altered sense of self in patients with TBI, in whom frontal lobe darnage is often prominent. This disturbance in self-awareness manifests in a denial or underestimation of their behavioral limitations, as well as a lack of insight into their poor social judgment and its behavioral impact on others, ieading to socially inappropriate behavior, also seen in frontal lobe patients. TB1 patients underestimate their social and emotional problems and demonstrate impaired perception in judging their most complex interpersonal skills. Thus, irnpaired self, and consequently, social awareness is a significmt result of TBI. In TB1 patients with impaired awareness of behavioral deficit, there was a higher incidence of bilateral lesions, particularly fiontal and parietal. He also reported a patient with nght frontal tumor who was similar to TB1 patients in dernonstrating lack of insight into social awareness. Thus, lesions of the prefkntal region may produce disturbances in the highest perception of one's social and interpersonal behavior. Darnasio (1994) also accords the fiontal lobe a crucial role for the development of personality and a concept of self. Adult patients with fkontal lobe lesions are known to demonstrate personality and behavioral changes (described in earlier section), impaired reasoning/decision-making, and decreased emotiodfeeling. Based on such observations in Phirieas Gage as a consequence of fiontal lobe damage, he argued that Gage's behavior indicated that something in the brain was concerned çpecifically with unique human properties, among them the ability to anticipate the future and plan accordingly within a complex social environment; the sense of responsibility toward the self and others; and the ability to orchestrate one's survival deliberately, at the cornmand of one's fiee will. In addition, Damasio(l994) described one patient with fiontal lobe injury sustained at the time of birth and another, at age 16. In both patients, there was a damage to the systems he considers necessary for nonnal human personality to emerge. Both patients shared a number of persondity 56 traits, e.g., they were ngid and peneverant in their approach to life, were unable to organize future activity and hold gainfil employment, lacked originality and creativity, and tended to boast, and present a favorable view of themselves. He noted that one way of describing their predicament is by saying that they never construct an appropriate theory about their perçons. or about their person's social role in the perspective of past and future. And what they cannot construct for themselves, they also cannot generate for others. They are berefi of a theory of their own mind and of the mind of those with whom they interact. Similar disturbances were reported in anosognosics with RHD in whom prekontal cortex is a part of the damaged system. These patients were found to be neglectful of their situation and of its consequences as they are of their paralysis. Many appear unable to foresee the likelihood of dire consequences; if and when they do predict them, they appear unable to suffer accordingly. They certainly cannot construct an adequate theory for what is happening to thern, for what may happen in the fiiture, and for what others think of them. Just as important, they are unaware that their own theorizing is inadequate. When one's own self-image is so compromised, it may not be possible to realize that the thoughts and actions of that self are no longer normal. From above evidence, as well as that obtained from fiontal lobotomy patients, Damasio (1994) concluded that bilateral prefiontal damage, when ventromedial sector is included, is consistently associated with impairments in reasoning/decision-making and emotiodfeeling with personaYsocia1 domain being the one rnost affected. Patients with such lesions can be said to demonstrate personality and behavioral changes indicative of a disturbance in self-image. This disturbed self- image is reflected in severely compromised personal and social behavior. Reviewing case studies of patients with fiontal lobe damage Damasio (1985) summarized "it seems probable that bilateral damage to the fiontal lobes in infancy or childhood produces a more devastating effect on personality and cognitive ability than the same amount of darnage sustained elsewhere in the brain at any time in the course of development.... early lesions of the frontal lobe are not compatible with normal development of intellectual abiiities and affect and consequently are not compatible with normal maturation of personality". T'us, the inability to be self-critical or self-reflective, a loss of reality testing and self- monitoring are key feahires of a disturbance in self-awareness following prefkontal, particularly nght frontal damage. A disorder of humor comprehension and production rnight be related to a disturbance in self-reflectiveness or an inability to be introspective. One result of a deficit in self- or reality-monitoring is socially inappropriate behavior, a fiequent consequence of fiontal damage. 57 This manifests in disinhibited behavior observed in frontal patients as witzelsucht and moria, a disorder of humor. The investigation of deficits in self-awareness and self-consciousness might be related to concepts of metacognition, the reflective ability to "know about knowing". Research in these areas is at a very prelirninary stage. Nevertheless, the study of hurnor deficits might be relevant. Normal comprehension and production of humor requires the ability to be introspective / self-reflective, as well as to view persona1 and social situations f?om different perspectives, your own and that of others. A disturbance in self-awareness produced by fiontal lesions might thus connibute to a humor deficit.

To sumrnarize the relationship between frontal lobes and hurnor, the above review of changes in patients with frontal lobe damage suggests that a number of processes required for normal functioning of humor appreciation and production are related to the £fontal lobe. The changes in language, personality, and emotional behavior in frontal patients suggest that the fkontal lobe plays an important role in mediating the interplay between cognitive and emotional aspects of behavior. Since humor occurs as the result of such an interplay, it seems likeIy that the fiontal lobe is important to humor. Many characteristics descnbed as typical of RHD and relevant to a humor disorder in these patients, are also cited as prominent features of f?ontal lobe damage. For instance, confabulation and embellishrnents reported as a RHD language deficit are also found with fiontal lesions. Rigidity or inability to think flexibly has been provided as an expianation for RHD language deficit, including hurnor. Inability to think in abstract terms, rigidity or inability to shift according to the demands of a situation is also a fiontal lobe deficit. Personality and emotional changes which occur as a consequence of RHD mimic those reported as consequences of fiontal damage. This leads to the speculation as to whether some of these RHD deficits can be disentangled fiom frontal lobe deficits or perhaps these are more appropriately considercd the realrn of the frontal lobes. That is, it is right fiontal damage and not RHD irrespective of locus that produces these deficits. In addition to language, personality, and emotion, other cognitive processes mediated by the frontal lobe, such as problem solving, working memory, cognitive flexibility, and visual directed attention are also important to humor. Metacognition and self-awareness, considered to be the highest of al1 integrated brain functions, are also associated with the fiontal lobe and are related to humor. Thus, many Ievels of frontal lobe fimctioning are important in humor. Summary of Literature Review: Research into the neuropsychological aspects of humor is very scarce. However, available evidence indicates that the right hemisphere rnay play a special role in the appreciation of humor. Two cognitive processes - sensitivity to surprise and ability tc establish coherence, have been identified as important to the comprehension of hurnor stimuli. Right hemisphere lesions appear to disrupt one of these components, i.e., the ability to revise an initial interpretation in order to integrate the punch line at the end of a joke or cartoon strip back with what has corne earlier in a discourse, thus producing a disorder in the comprehension of humor. This right hemisphere involvement in hurnor is related to its role in rnediating pragmatic linguistic and nanative abilities, as well as, in personality and emotions. No neuropsychological studies are available on the production of humor but anecdotal evidence implicates the right hemisphere. Further localization of hurnor within the right hemisphere has not been made. However, changes in language, personality, emotional, and social behavior following frontal lobe damage; the proposed requirement of fiontally mediated processes such as problem solving, working memory, cognitive flexibility, abstraction, and directed visual attention for hurnor appreciation; and the relevance of humor to processes of metacognition and self-awareness subserved by the fiontal lobe, suggest that this region is important in mediating humor. Since, many of these impairments, particularly those involving personality and emotional change and self-awareness are associated with damage to the right Bontal region, this region within the right hemisphere may be the locus of deficits in hurnor appreciation and production.

8. A~iwand Humor The role of humor in the care of the elderly is increasingly being recognized by professionals working in the field of gerontology. The many recommendations for the use of hurnor with the elderly include its therapeutic effects (Ewers et al., 1983; Raber, 1987; Richman, 1995; Simon, 1988; Williams, 1986); for enhancing quality of life (Kelly, 1993; McGuire, Boyd, & James, 1992); for assisting in the management of stress and coping with the stresses of aging (Cohen, 1993; Prerost, 1993; Simon, 1988; Tennant, 1990). There have also been suggestions that humor may influence the process of aging well (Solomon, 1996) and that there may be a positive relationship between humor and longevity (Yoder & Haude, 1995). Although much of the information regarding the healing powers of humor appears to be anecdotal, it is increasingly 5 9 being accepted as a valuable tool for health professionals dealing with the care of the elderly. Despite the growing recognition of the contribution of humor to physical and psychological well-being throughout the life-span, it has not received much scientific investigation, especially with the aged. The study of aging to a great degree emphasizes deteriorathg abilities. For example, the aged perform far worse on reaction time than younger individuals (reviewed by Birren et al. 1980; Salthouse, 1985) than when we look at the highest levels of human functioning. Other qualities of the elderly, however, have been developed and nurtured over the years. Hurnor is valued particularly highiy by the old, who consider a sense of humor close to the quality of wisdom. Humor has been suggested as having great potential for the study of aging. Changes with aging can be examined to increase knowledge about humor, or humor cm be studied to shed light on the process of aging. Also, humor is reported to be valued particularly highly by the old, who consider a sense of humor close to the quality of wisdom (Nahernow, 1986). Hurnor not only adds an important dimension to our knowIedge of hurnan fùnctioning, but serves as a data base for the study of aging that will serve to celebrate the aging process. Nahemow (1986) suggested that it should be added to the to-be-studied list in the psychology of aging. The value of humor in the aging process has been ernphasized by Fry (1986), who regards humor, mirth, and mirthfiil laughter as one of the factors that can diminish, offset, and compensate for the problems associated with aging. He reviewed the information available about the physiologie impact of humor, mirth, and rnirthful laughter on the circulatory, respiratory, skeletal, muscular, autonornic, and central nervous systems and concluded that humor physiology involves the participation of most, if not al1 of these major systems in significant and beneficial ways. He recommends humor as a coping mechanism for successfilly dealing with disadvantageous circumstances, addressing some health needs, and for improving life quality for the elderly. The present study investigated the appreciation and production of humor in an elderly population. Since this study focused on the neuropsychological examination of humor, as well as the cognitive processes involved in humor appreciation and comprehension, the aged were thought to be a particularly relevant population. Research in the neuropsychology of aging currently encompasses the full range of behaviors and their neurological substrates. There is a growing recognition that some functions mediated by the fkontal lobes may be particularly vulnerable to change with aging (e.g., Moscovitch & Winocur, 1992; Stuss et al., 1996). Since 6C the present study hypothesized that the fiontal lobes would be especially important in mediating humor processes, and since the fkontal lobes are thought to be disproportionately affected by aging, the study of humor in the elderly would provide important evidence regarding both humor, as well as fiontal lobe functioning in this population. Structural changes have been reported as a consequence of aging with particular emphasis on the fiontal lobe. CT and MRI scanning techniques have been used to examine age-related changes in a variety of brain regions. Although other brain regions have also been implicated in these studies, disproportionate changes were reported for the frontal lobes (Albert & Stafford, 1986; Jernigan et al., 1991). Coffey et al. (1992), using MRI found that increasing age was associated with a statistically significant decrease in the total volumes of cerebral hemispheres, with the rate of change in brain volume with age being substantiaily greater for the fiontal lobes than for other regions. De Santi et al. (1995) employed PET and found age related metabolic reductions in al1 fiontal and temporal lobe regions with normal aging with the greatest changes in the frontal lobe, particularly the dorsal lateral fiontal region. Murphy et al. (1996) using both MN and PET scanning techniques found significant age-related decrements in brain-matter volumes as well as glucose metabolisrn in the fiontal regions. In the PET study, the right frontal region was reported to be more affected than the left. Neurochernical changes in the fkontal lobe parallel those reported in structural imaging studies. Wang et al. (1995) used PET scanning to assess age-related changes in serotonergic 5- HT, and dopaminergic D2 receptor availability. Both types of receptor availability decreased significantly with age, particularly in the frontal cortex. Thus, there appears to be a consensus ftom a number of studies using a variety of techniques that have documented age-related changes in the fiontal regions. Research into neuropsychological functioning in normal aging provides additional evidence that fiontal lobe fimctions may deteriorate with age. Albert & Stafford (1986) in their review found the highest correlations with performance on neuropsychological tests of naming, abstraction, and rnemory a CT slice which contained primaily fkontal and temporal lobes. Age-related deficits are reported on tests considered to be particularly sensitive to frontal lobe lesions. For instance, elderly people show greater interference on the Stroop test cornpared to the young (Cohn et al., 1984; MacLeod, 1991). Age was also found to have significant effects on al1 variables of the WCST (Leach et al., 1991). 61 Further evidence of a decline in fiontal lobe functions with aging comes fiom research into memory deficits in this population. Moscovitch and Winocur (1992% 1995) reviewed rnemory studies in aging and reported a remarkable consistency between the memory deficits seen in human patients and experimental animals with fiontal lesions and those seen in normal aging. Moreover, in many instances, performance on the frontal memory tests correlated significantly with performance on non-mnemonic tests of fiontal function in the elderly but not with performance on other tests. They contend that the type of memory deficits observed in the elderly is a working-with-mernory deficit, which captures the essence of the impairment associated with fiontal lesions. What is irnpaired in the elderly is not the mernory itself but the uses to which mernory is put, the inferences based on mernory, the temporal ordering of remembered episodes, their placement in proper contexts, and implementation of encoding and retrieval strategies with respect to particular events. The authors noted that deficits on these types of tests are often s-g and are found consistently in patients with fiontal lesions and in elderly people with presumed fiontal dysfunction, whereas performance on more traditional memory tests may remain unimpaired. A relation arnong normal aging, memory, and fiontal lobe was also reported by Craik et al. (1990) where measures of source arnnesia, a foim of episodic memory deficit considered to be related to dysfunction of the prefiontal cortex, correlated with age, as well as scores on neuropsychological tests of frontal lobe function, i.e., verbal fluency and perseverative errors on the WCST. Thus, the type of memory deficits observed in the elderly lend support to the idea that fimctions that depend on the fiontal systems detenorate with age. Axelrod et al. (1992) admuiistered the Mini Mental State Examination (MMSE) along with tests sensitive to fiontal lobe functioning, i.e., WCST, design fluency, and similaxities subtest of the WAIS-R to eighty normal older adults in four age grouping fkom 50 to 89. A single composite score was derived based on raw scores korn the three neurocognitive tests to obtain the frontal lobe neurocognitive composite score which decreased across age groups indicating a significant decline in frontal lobe functions across the ages. This age-related cognitive derline on fiontal lobe tasks was also detected by the performance on the MMSE, which also declined significantly across age and was significantly positively correlated with the frontal lobe neurocognitive composite. 62 Thus, evidence fkom research exarninùig neuroanatomical and neurochernical, as well as neuropsychological changes points to a decline in fiontal lobe structure and function during the course of normal aging. The fiontal cortex, however, comprises a heterogeneous structure, consisting of a number of anatomically distinct areas that have different phylogenetic and ontogenetic histories (Pandya & Bames, 1986). Therefore, different regions within the prefiontal cortex may be associated with different functions. Since investigation into the changes in fiontal lobe functioning with aging is quite recent, and Mer,since information regarding the bctions of the subregions of the fiontal lobe still remains quite elusive, it is not yet clear whether some frontal lobe subdivisions and the functions associated with them deteriorate more rapidly as a consequence of aging. Some tentative evidence is present which indicates that performance of the elderly on neuropsychological measures may be more similar to that of patients with right frontal darnage, indicating that there might be some hemisphenc asymmetry in frontal deterioration with age. Kaplan ( 1980) analyzed the strategy employed b y the elderly on certain problem-solving tasks (the Block Design subtest of the WAIS, the Rey-Ostemeth Complex Figure and the Hooper Visual Organization test} to examine whether en route to a correct final solution the older subjects may reveal cognitive styles or errors that are pathognomonic of different lateralized lesions. On al1 these tests, the source of the error and the quality of the errors made by the elderly were strikingly similar to those made by patients with lesions in the right fiontal region. This suggests that the nomal elderly demonstrate what resembles right fiontal pathology. Stuss et al. (1996) investigated whether age-related decline in memory performance was due to fiontal lobe dysfunction by comparing normal individuals (young, rniddle-aged, and older) with three groups of patients who had demonstrated Iesions in the right, lefi, or bilateral &ontal regions. A list learning task was employed since performance on the task had been shown to be dissociable within the fiontal lobe. Results showed that older subjects had a modest impairment in list learning, particularly on more difficult, less stmctured Iists and also that this deficit was equivalent to that seen with unilateral right but not unilateral left or bilateral fiontal lesions. Both older controls and unilateral nght fiontal patients showed a deficit in subjective organization. It was suggested that it was possible that list learning deficits in normal older people represents poor use of ordering strategy based on right dorsolaterai frontal dysfunction because these two groups were comparable in performance on this measure. The right fkontal group also produced additional executive impairments in monitoring (Le., more errors and 63 inefficiencies) that were not striking in the elderly participants, although their performance was worse than the younger groups. The authors indicated that overall the qualitative nature of recall performance, particularly as rneasured by indices of organizational control processes was similar between older normal and patients with frontal damage, particularly those with right Frontal damage. That is, at lest some of the decline in older people in tasks which measure executive or supervisory abilities would be attributable to fiontal system dysfunction. To surnmarize, imaging studies indicate structural and chemical changes in the frontal lobe with aging. Neuropsychologïcal investigations also suggest a decline in certain functions mediated by the fiontal regions as a consequence of normal aging. There is some tentative evidence that there might be some hemispheric asyrnrnetry in frontal lobe dysfunction, with the nght fkontal region being more affected with aging. Humor, although of great value to the elderly, has been neglected as a topic of empincal investigation in this population. A neuropsychological study of humor is particularly relevant since there is growing evidence regarding changes in the frontal lobe structure and hctions with aging. Hurnor provides an avenue to investigate higher-order functions mediated by the Erontal lobe. The present study examined humor appreciation and comprehension in an elderly population, as well as some of the cognitive processes involved in humor, particularly those mediated by the fiontal lobe. Rationale for the present studv Literature review suggests that an empirical investigation into the role of the frontal lobes in humor would be a prornising and worthwhile effort as the next logical step towards a neuropsychological understanding of humor and for anatomical localization of hurnor processes. The aim of the present study was to investigate: 1) individual differences in the appreciation of huiiior; 2) the cognitive processes involved in humor appreciation and production; 3) whether these cognitive processes could be dissociated resulting in different types of errors on humor tasks; 4) whether these cognitive processes were mediated by specific brain regions, specifically the fi-ontal lobes. The performance of patients with nght-, left-, and bi-frontal lesions on tasks designed to assess different aspects of humor appreciation and production, and the cognitive processes involved, were compared with that of patients with lesions outside the fiontal lobe. This enabled the examination of the effect of the location of lesion on humor appreciation and production. Performance of the patient groups was compared to that of a matched group of normal participants. In addition, tests which assessed cognitive processes such as working rnemory,

cognitive flexibility, abstraction, and directed visual attention were administered in order to assess whether deficits in these fiontally mediated processes were correlated with poor performance on humor tasks. The study made the following contributions: 1. Replication of some earlier research on humor in brain-damaged patients. 2. Design and development of new humor tests to measure various aspects of hurnor appreciation and delineation of some of the processes involved. 3. Investigation of production of humor in brain-damaged patients. To date, this aspect of humor has received no investigation in neuropsychology as reflected in the absence of any published study on humor production in the neuropsychological literature. 4. Provided more specificity in ternis of brain regions involved in humor. Previous research pointed to the role of the nght hemisphere in humor; however, Merlocalization was not available. This study investigated the role of specific brain regions, in particular, hpothesizing that the frontal lobes were maximally involved. 5. hvestigation of some of the cognitive processes involved in humor appreciation in ternis of their relation to specific brain regions. Specifically, many frontdly mediated processes were hypothesized to play an important role. Deficits on humor tasks were therefore correlated with 65 deficits on tasks measuring functions hypothesized as contributhg to humor functioning, such as working memory, cognitive flexibility, abstraction, and visual directed attention. 6. Examination of humor appreciation and production in nomal aging and the relationship of hurnor to fiontally mediated hctions of working memory, mental shifting, abstraction. and visual directed attention in this population. This study therefore provided a more thorough and systematic neuropsychological investigation of humor than was presently available. III. METHOD

Subiects Patients with neurological disorders were compared with nomal control subjects. Neuroanatorny Investigation of the effect of specific location of brain damage on deficits in appreciation and production of humor was a major focus of this study. Localization of lesions were therefore performed in detail. Major classification of neurological patients was into those with fiontal (including striatal) pathology venus those with lesions restricted to nonfkontal regions. Patients with lesions in the frontal lobe were Mersubdivided into unilateral (right versus left) and bilateral involvement. Only patients with circumscribed lesions who could be classified into one of the following groups were therefore included in the study - (1)left frontal, (2)right frontal, (3)bifiontal, (4)left posterior, and (5)right postenor. That is, patients with lesions involving multiple lobes were excluded. Aithough this limited the sample size, this was felt to be necessary in order to obtain specificity of results regarding the brain region hvolved in humor. This design made it possible to amibute humor deficits observed in a particular patient group to darnage to the specific region (lobe) involved in that group, rather than to a broader region (such as the hemisphere involved). This provided specificity of lesion location compared to previous research. Classifications of neurological patients were based on CAT scans and \ or on neurological examination. The fissure of Rolando was used as the anterior \ posterior line of demarcation. Preference for inclusion in the study was given to: 1) patients with brain lesions seconda. to vascular disease; 2) those with small encapsulated surgically removed turnors; and 3) head injured patients who had primarily localized pathology. Efforts were made to equate groups on the etiology of lesion. Cases with diffùse brain danage, history of multiple events, or generalized problems such as seinires were excluded. Clinical and demographic details of patients are presented in Tables 1 and 2. Both the patient and norrnal subject groups met the following inclusion criteria: absence of a previous history of psychiatnc or neurologie disorder; age between 18 and 70; and conversational fluency in English. Normal control subjects matched with the patient groups on the basis of sex, age (25 yean), and level of education e2years). The aged group included 20 participants above 70 years of age with a mean age of 73 yean (SD=4.6). The young group consisted of 17 participants with a mean age of 28.8 years (SD=4.9).

Table 1. Patient charactenstics

-- Patient # Sex Age Etioiow Lesion Site Left frontal

Tumor Polar (Dorsolateral, medial) Tumor Frontal Tumor Dorsolateral Tumor Medial, Dorsolateral Stroke Medial, Septal Trauma Inferior-mediaI, Dorsolateral

Right Frontal

Tumor Superior media1 Stroke Merior medial Lobectomy Dorsolateral

Bifrontal

Stroke Medial, Septal Leukotomy Bilateral, Orbitofrontal Lnfârc t MediaI, Dorsolateral Trauma Inf'erior medial (right), Dorsolateral (left)

Left Postenor

Lobectomy Temporal Lobectomy Temporal Lobectomy Temporal

Right Posterior

Hemorrhage Temporal Lobectomy Temporal Stroke Parietal Stroke Temporal, Parietd Stro ke Temporal Table 2. Scores on neuropsvcholo~caltests

Patient Yrs-of Vocab To ken JOL BDI WCST Edu.

Left frontal 1 2 3 4 5 6 Mean SD

Right Frontal 7 8 9 Mean SD

Left Pos terior 14 15 16 Mean SD

Right Postenor 17 18 19 20 21 Mean Right Frontal Left Frontal 70 Bilateral Frontal Left Non-Frontal

Right Non-Frontal Experimental Tas ks The experimental tasks were used to investigate different aspects of humor hctioning. Various tasks were designed to assess humor appreciation / comprehension, sense of hurnor and humor production. Humor Appreciation 1. Funniness rat in^ Scale This scale was developed for use in the present study. It consisted of a list of 28 short printed statements (See Appendix 1). These included 21 hurnorous and 7 neutral or nonhurnorous items rnixed randomly. Each item was printed on a separate 6 by 8" card for presentation to the participants. The participant's task was to rate each statement according to how funny she\he thought it was, using the following 5-point rating scale: 5--Extremely funny; 4--Very -y; 3-- Quite funny; 2--Slightly funny; and 1--Not fünny. The 5-point rating scale was printed on a separate card. The items are presented in the appendix. The instructions were as follows: "1 am going to show you some cards one by one. On each card is a sign. These are signs in English that were found in countries around the world written by people whose first language is not English and who are not quite familiar with English idioms. As a result, some of the signs tum out to be quite amusing. Rate each of the following signs on this 5-point scale according to how funny you thùik it is: Rate it a 5, if you think the sign is extremely -y; 4, if you find it very funny; 3 for quite My;2 for slightly hy;and 1 if you think it is not funny." Administration: Part 1: The card with the rating scale printed on it was placed on the table in fiont of the participant and the examiner pointed to the numbers on the card while the instructions were being given. After the instructions, the card was moved a little to the right and placed there for the entire duration while the stimulus cards were presented. The 28 cards were then presented to the participant one by one. After reading each card, the participant informed the examiner of hermis rating. The examiner circled the participant's rating for each item on a sco~gsheet. In addition, the examiner observed the participant while each card was being read and noted the reactions, Le., whether the participant smiled, laughed or made any verbalizations. Part 2: This part of the task attempted to deteraine whether participants had undeetood the humor intended in the stimuli. Mer the participant had rated al1 28 statements, the examiner selected 5 items for which the ratings were 3--Quite Funny, 4--Very Fiinny or 5--Extremely Funny. The participant was then told, "For some of the items that you just rated as being hy.1 am going to ask you to explain the reasons why you thought they were funny." The examiner then placed one of the 5 items selected in fiont of the participant. For instance, if the participant had given a rating of 4 to item 6, then the card with this statement was presented with the

instruction, "When you rated this statement, you gave it a 4, that is, you found it very funny. Now, can you explain to me what made you think this statement was very funny?" The response of the participant was recorded verbatim. The remaining items selected were similarly presented and the participant's reasons for finding hurnor in them were recorded. A pilot study using neurologîcally intact subjects suggested that this test was a sensitive rneasure to examine individual differences in humor appreciation, as well as enabling investigation of variability of performance among individuals, providing measures of humor appreciation of a wider range (Sharnrni, 1993, Unpublished research). Part L of the task assessed hurnor appreciation using a purely verbal task, while Part 2 allowed us to examine the reasoning employed by the participant in evaluating the humor contained in the statements.

2. Jokes and Storv Completion Task: The Jokes and Story Completion Task was used to investigate some of the cognitive processes involved in the appreciation of humor stimuli (See Appendix 2). in this experiment, an attempt was made to understand to a greater degree the underlying processes involved in humor appreciation in tems of their relation to various brain regions. Two elements or cognitive processes identified as necessary for successful appreciation of humor in narrative processing were investigated - surprise and coherence (explained in the review). This was done by employing tasks involving jokes and short stories. Both tasks presented a situation with the ending omitted and required the participants to complete the presentation from a choice of 3 or 4 different ending types. In the Joke condition, the elements of surprise and coherence were studied in their relationship to humor, since intact functioning of both is required to appreciate hurnor in jokes. Whether brain darnaged patients utilize these two processes appropnately, or whether there might be a deficit in either one of the processes or in both, was investigated by exarnining performance of normal and brain darnaged participants in terms of the ending type chosen to complete the joke. Performance in the Joke condition was compared to that in the Story condition. Since hurnor was not involved in this condition, surprise was not appropriate and only ability to establish coherence was required. Intact functioning of the element of coherence was reflected in the choice of ending type selected by the participant to complete the story presented. This task included two conditions, a joke and a story condition. This task was developed by Brownell et al. (1 983) and Bihrle et al. (1986) for use in their study investigating comprehension of hurnorous and nonhumorous materials by brain-damaged patients (used with the authors' permission). The stimuli for the Joke condition consisted of sixteen jokes standardized for length and presented in the same pseudo-random order to al1 participants. The punch line at the end of each joke was omitted. Each stimulus was presented with four possible ending types: correct funny choice (FC) which is the onginal punch line that was omitted; straightfonvard ending (SF); associative non sequitur (ANS); and humorous non sequitur (HNS).

Example: The neighborhood borrower approached Mr. Smith Sunday noon and inquired "Say Smith, are you using your lawnmower this afternoon?" "Yes 1 am" Smith replied warily. Then the neighborhood borrower answered: Ending Twe [SF] 1. "Oh well, can 1 borrow it when you're done then?" [ANS] 2. "The birds are aiways eating my grass seed". WS]3. "OOPS!" as the rake he walked on barely missed his face. @?Cl 4. "Fine, then you won? be wanting your golf clubs, 1'11 just borrow them". The following instructions were presented to the participants: "Some jokes are presented below. Each of them will have the punchline, that is, the last line or funny ending, left out. Following each joke 4 possible endings to the joke are also presented. Please pick the one you think is the correct, funny ending. When you have picked the ending that you think is the correct punchline to the joke, 1 want you to rate the joke accordhg to how funny you think it is, using the following 5--point rating scale: 5--Extremely funny; 4-Very -y; 3-Quite funny; 2-- Slightly by;and 1--Not fùnny." The 5-point rating scale was printed on a separate card. An example was presented first with the correct funny choice underlined. The huo conditions - jokes and stories - together allowed the dissociation of surprise and coherence elements involved in humor comprehension. They provided a means of studying whether patients have an intact appreciation of the surprise element in a narrative, i.e., the ability to know when surprise is appropnate and when it is not. If patients were sensitive to the surprise element of humor, they should be able to apply it appropriately in the case of jokes and refrain fiom applying it in the case of stories. In addition to sensitivity to surprise, humor also required the ability to revise an initial interpretation, thereby establishing coherence between the punchline and the rest of the joke. Thus, intact functioning of both the elements of surprise and coherence was required for humor appreciation. Similarly, if patients had a difficulty in establishing coherence, this impairment should affect performance in other narrative tasks, such as choosing a correct, coherent ending for nonhumorous items such as stories. For short stories, since surprise was inappropriate, only the ability to establish coherence was required (Bihrle, et al,, f 986). In this task, there was one correct ending to each item (the funny choice - FC) and three incorrect endings. The choice of the correct fhny choice (FC) indicated both a preserved sensitivity to surprise as well as the ability to establish coherence. Both these elements are considered essential for normal appreciation of humor. Of the three incorrect endings, the two nonsequitur endings [associative (ANS) and hurnorous (HNS)], like the correct ending, included an element of surprise, that is, they did not follow directly from the joke's beginning. However, unlike the correct ending (FC), the nonsequiturs lacked coherence, Le., they could not be coherently integrated with the premises on a second level to form an acceptable resolution to the joke's story. Therefore, the choice of a nonsequitur ending indicated a preserved sensitivity to the surprise component of humor but an inability to integrate the body of the joke and its punch line into a coherent interpretation. The third incorrect ending, the straightforward endhg (SF) followed directly from the joke's beginning. The straightfonvard ending (SF) complemented the nonsequiturs in that it preserved a coherent sense of story but provided no discontirmation of expectations; choice of îhis incorrect ending indicated an insensitivity to the importance of surprise in humor. Thus, only the choice of the correct funny ending (FC) indicated intact functioning of both the surprise and coherence elements necessary for appreciation of humor. Choice of any of the other three ending types indicated a deficiency in one of the two elements. Choice of one of the two nonsequitur endings indicated a preserved sensitivity to the surprise element, but impaired ability to establish coherence. Ln contrast, the choice of the straightforward ending (SF) indicated ability to establish coherence, but an insensitivity to the surprise element. The Story condition was designed as a control condition. It consisted of the same 16 short story jokes used in the Joke condition. However, these were presented with only two types of endings - straightforward ending (SF) and two types of nonsequiturs, associative nonsequitur (ANS) and humorous nonsequitur (HNS). The funny ending was not presented as a choice. The only correct response was the straightfonuard ending (SF). Selection of this ending (SF) indicated the ability to establish coherence when humor was no t involved. The following instructions were presented in the story condition: "The following are shon stories describing a situation in real Iife. At the end of each you are given four possible endings to the story. You pick the one that has the sarne main idea as the rest of the story - the one that completes the story in a Iogical way". An example was presented first with the correct straightforward ending underlined. Here, the only correct choice was the straightforward ending (SF), which completed the short story in a coherent fashion. Choice of one of the nonsequiturs was incorrect. Selection of a nonsequitur indicated that the participant responded with surprise to situations where surprise was inappropriate. Cornparison of performance between the joke and story conditions allowed an exarnination of participants' utikation of the elements of surprise and coherence and their application in appropriate contexts. This experiment using the Joke and Story cornpletion task, allowed us to dissociate whether an individual with a lesion in a particular region of the brain has intact hinctioning of both elements (surprise and coherence) necessary for humor appreciation, or has impairment in one or both of these elements.

3. Cartoon Rating The Cartoon Rating task consisted of 32 different cartoons selected fiom various published books of cartoons. These items were used only for research in the present study and are not reproduced anywhere for copyright reasons. Each cartoon was accompanied by a verbal caption printed beneath it. The 32 cartoons were divisible into 4 groups with 8 cartoons in each group, depending on the type of caption that accompanied it. The four groups were as follows. Only Group 1 consisted of cartoons which were presented exactly as they appeared in the original work published by the cartoonist. For these items, the verbal captions had to be read and incorporated with the picture in order to appreciate its hurnor. Thus, Group 1 consisted of Funny cartoons. The remaining three groups comprised cartoons for which the accompanying captions were those that were inserted for the purposes of this study, replacing the originzl captions of the cartoonist. Group 2 was made up of cartoons with captions depicting slapstick situations. Group 3 compnsed cartoons with captions which were neutral (not funny) but were relevant to the cartoon picture. Group 4 also consisted of cartoons with captions which were neutral (not fumy) but with no direct relevance to the cartoon picture. The 4 groups of cartoons were presented in the same random order to al1 participants. The participant's task was to rate each cartoon according to how Mysheihe found it, ushg the following 5--point rating scale: 1--Not Funny; 2--Slightly Funny; 3--Quite Funny; 4--Very Funny; and 5-Extremely Funny. The rating scale was pnnted on a card. Instructions: "1 am going to show you some cartoons one by one. After you have seen each cartoon, 1want you to tell me how funny you think it is, using this scale. If you think the cartoon is not fùnny Say 1, if you think it is slightly fünny Say 2, if it is quite funny 3, very funny 4, and if you find it to be exiremely funny Say 5". Administration: Part 1: The card with the rating scale printed on it was presented at the time of the insûuctions and placed in fiont of the participant while al1 32 cartoons were being rated. The cartoons were presented to the participant one by one. The examiner recorded the rating given by the participant to each cartoon on a rating sheet. ui addition, the examiner observed the participant's reactions to each cartoon and made a note of the participant's srnile, laughter, or any verbalizations. Part 2: After al1 32 cartoons had been presented and the ratings obtained fiom the participant, the rating card was removed fiom the table. The examiner selected 5 cartoons which had been given a rating of 3--Quite Funny, or higher. The participant was asked to explain the reasons why these cartoons were rated as being funny following the same procedure as in Part 2 of the Furininess Rating task and the responses were recorded. Part 1 of the task assessed humor appreciation through the medium of cartoons, while Part 2 ailowed us to examine the reasoning employed by the participant in evaluating the hurnor contained in the cartoons. This task has a verbal component in the fom of captions, which had to be integrated with the pictures in order to appreciate the humor contained in the cartoons. The cartoon pictures or the verbal captions by themselves were not as humorous. Since all 32 cartoons were taken fiom the same artist, the cartoon drawings were of a similar nature and attention had to be paid to the captions in relation to the drawing to appreciate humor. The four different groups of cartoons were employed to investigate whether patients could discriminate between the genuinely funny cartoons versus the slapstick and the neutral items.

4. Cartoon Arrav Task This experiment investigated factors contributing to the appreciation of visual humorous displays, Le., the ability to conduct a visual search andlor focus on relevant details. The Cartoon Array task examined a different genre of cartoon humor from that studied in the Cartoon Rating task described earlier. Here humor was contained within an individual cartoon picture. A visual search of the cartoon picture was required so that attention could be focused on a particular tell- tale detail for the humor to be recognized. There were no verbal captions, so verbal mediation was minimal in this task. The task consisted of 10 stimuli. Each stimulus was made up of an array of 4 pictures presented on a single sheet. Al1 four cartoons constituting an array were essentially identical, the single difference being a 'tell-tale detail' which appeared in only one cartoon, the correct or funny choice. Equivalent but nonhumorous details were incorporated into the remaining three cartoons in the array. There were no verbal captions associated with any of the cartoons in the array. The correct or Mycartoon could only be understood if the participant searched the display and focused on the relevant, i.e., tell-tale detail, integrating it with the general context. Since the cartoons in an array were essentially identical only differing in terms of the tell-tale detail, all other factors which might aid in the appreciation of humor in cartoon displays were held constant. This task, therefore, examined the effect of subjects' ability to search and focus on relevant details as a factor in humor appreciation. The stimuli were prepared by selecting cartoons appearing without captions in various issues of the New Yorker magazine. These were used only for research in the present study and are not reproduced anywhere for copyright reasons. The original cartoon was photocopied 3 times. For each photocopy, an artist erased the original tell-tale detail which was critical for humor appreciation and added a nonhumorous detail in keeping with the entire picture. The copies which had been altered by the artist were photocopied again so that no traces of the alterations were visible. The three altered copies could not be told apart from the original humorous cartoon. 10 cartoon drawings were thus selected and copies were altered to produce the stimuli for the test. The original fûnny cartoon and the three altered cartoons for each stimulus were placed in a 2 by 2 array for presentation such that the bycartoon appeared randomly in a different position in the array for the 10 stimulus items. Instnictions: "1 am going to show you some cartoons one by one. On each sheet you will find four individual cartoons. 1 want you to look at al1 four cartoons and then point to the one that you think is the funniest among the four cartoons on the sheet. Mer you have picked out the funniest cartoon, 1then want you to rate that cartoon according to how funny you think it is, using rhis rating scale: 1--Not Funny; 2--SlightIy Funny; 3--Quite Funny; 4--Very Fumy; and 5- Extremely Funny''. Administration: The rating scale was printed on a separate card and placed in front of the participant for the duration of the task. The 10 stimulus arrays were then presented one by one. After seeing each array, the participant would point to the one cartoon in the array which she/he fowd to be the funniest. The participant's response was noted by the examiner. Afier the funniest cartoon in the array had been selected, the participant's rating regarding its funniness was also recorded. The examiner dso made a record of the participant's behavioral responses during the task, i.e., srniles, laughs, and any verbalizations.

Sense of Humor In addition to appreciation of hurnor, participants' sense of humor was also investigated. Two tasks were used to evaluate sense of humor. First, participants were asked to rate their own sense of humor using a rating scale. Instructions were as follows: "1 am interested in obtaining your estimation of your own sense of humor. Please rate your sense of humor on the scale given below by placing a circle around a number on the scale. For example, if you think you possess an 'average' sense of humor, give yourself a rating of '5'. If you think you have 'no sense of humor', give a rating of IO'. If you think you have a 'high sense of humor', rate yourself a '10'. If you think your sense of humor falls on other points on the scale, please encircle the corresponding number'. A line was presented below the instructions with the numbers printed at equal distances as shown below: This task provided a measure of the participant's self-evaluation of their sense of humor. It was hoped that the inclusion of this task would provide some information regarding patients' ability to reflect upon and monitor their own cognitions and capacities. A potential problem that is present when self-report scales are used to evaluate socially desirable traits is that of self-report bias. To overcome this problem, a second measure of sense of humor was also employed, the Sense of Hurnor Questionnaire (SHQ), published by Svebak (1974). This scale was designed to assess generalized individual differences in humor appreciation and production. It is based on the author's reasoning that sense of hurnor involves three essential elements: (a) metamessage sensitivity, or the ability to recognize humor in situations; @) personai liking of humor, or the enjoyment of humor and the humorous role; and (c) emotional permissiveness, or the tendency to fkeely express one's emotions (Svebak, 1974). Accordingly, the SHQ is compnsed of three subscales corresponding to these three elements. The scale includes 21 items with seven items in each of the three subscales. Instructions: "This questionnaire is concerned with the way you express and experience humor. Obviously, there is wide variation amongst individuals and therefore no right or wrong answers to these questions. Below you will hda list of 21 statements. In the space at the beginning of each sentence, please indicate the degree to which you agree or disagree with that statement by writing a 1-strongly disagree; 2 - mildly disagree; 3 - mildly agree, or 4 - strongly agree." The participants completed the questionnaire by themselves, reading each item and indicating the extent of their agreement or disagreement by writing the corresponding number beside it.

Humor Production Two types of tasks were ernployed to assess humor production. The first, Production of Humorous Captions, was used to examine participants' ability to create their own hurnor in response to stimuli that were provided to them. The second, Tell a Familiar Joke and Read Jokes, was used to examine participants' ability to narrate a joke. The purpose of this second task was to assess language production, in particular, the kind of narrative ability that is required to recite humorous material. 1. Production of Humorous Captions This task consisted of 10 cartoon pictures, each presented on a separate sheet of paper. The stimuli were selected fiom cartoon drawings published by Unger. The verbal captions written by the author which originally accompanied the cartoons were deleted, so that only the cartoon picture appeared on the sheet presented to the participant. The participant was then instructed to create herhis own caption to go with each cartoon so that the pictures would be turned into humorous cartoons. Instructions: "Here are 10 drawings. I want you to create verbal captions to go with these drawings which will turn them into humorous cartoons. You can spend about a minute or two on each drawing and write the funniest caption that comes to your mind, beneath each drawing".

2. Tell a Joke and Read Jokes These tasks were used to assess language production with regard to humorous matenal. Participants were videotaped while performing both these tasks. Tell a Joke: Participants were asked to spontaneously narrate a familiar joke. They were prepared for this task by informing them at the beginning of the testing session that they would be required to tell a joke at the end of the testing session. Xnstmctions: At the start of the testing session the following instructions were given: "At the end of today's testing, 1am going to ask you to tell me a joke. So if a joke comes to mind during the testing session I'd like you to remernber it so you cm tell it to me later when 1ask you". At the end of the testing session the participants were instructed as follows: "Tell me any joke that you know". If the participant failed to narrate a joke at this time, shehe was instructed: "1 will give you a few minutes to try and see if you can remember any joke that you might have heard or read recently". If the participant still was unsuccessful in remembering a joke, three prompts were provided as follows: "Do you know any joke about an animal?" If this prompt failed, "Do you know any joke about a bar? And "Do you know any jokes about lawyers?" If they were still unsuccessful in recalling and narrating a joke, this part of the testing was concluded. This task of Telling a Joke was used to assess memory for old humor. Read a Joke: Three short written jokes were presented to the participant who was requested to read them out loud. Instructions: "There are three short stories on this sheet. Could you read them out loud?" The instructions did not indicate that the stories being read out were actually jokes. However, afier reading the first or the second 'story ', the participants would presumably 'catch on' that they were reading jokes. Participants were rated on the extent to which their reading of the jokes contained humorous prosody and intonation, as well as, their success in the telling of the joke. It was expected that these abilities would improve with each successive reading of the jokes.

Baseline Neuropsvcholo~icalTests These tests were used to assess general intellectual ability, oral comprehension, visual perception, and feelings of depression.

1. WAIS-R VocabuIary Subtest This test was used to obtain a measure of general intellectual ability. It consisted of a list of 35 words. Participants were asked to tell the meanings or definitions of these words (Wechsler, 198 1).

2. Token Test This test was used to assess oral language comprehension (Benton & Hamsher, 1989). It consisted of twenty small and large circles and squares in five colors (red, black, green, yellow, white), which were ernployed to assess the participant's ability to comprehend and carry out simple commands.

3. Jud~rnentof Line Orientation This test was used to assess visual perception. It consisted of 30 items, each showing a different pair of angled lines to be matched to the display cards @enton, et al., 1983). Scores on this test were correiated with that on the Cartoon test to assess the relation of visual perception to the appreciation of cartoon humor. 4. Beck Depression Inventorv (Short Forrn) This test was used to screen for depression by self-report statements (Beck & Beck, 1972). The test consisted of 13 four-choice staternents. The participant checked the choice or choices rnost appropriate to him or her. The score obtained on this scale was correlated with performance on hurnor appreciation tests to ensure that feelings of depression did not unduly affect performance.

Tasks for Measurement of Concurrent Processes Involved in Humor The following tasks were used to assess patients' performance on processes mediated by the Erontal Iobes which were believed to be essential for humor. Performance on these tasks were correlated with performance on specific hurnor tasks.

1. The AIpha S~anTest The Alpha Span task was used to assess working memory (Craik, persona1 communication). This is a word span test in which the participant was presented a series of words. The participant's task was to repeat the senes back after arranging the words in alphabetical order. nie test began with three words in a trial and increased in length during successive trials. This was continued until the participant failed on two consecutive trials.

2. Wisconsin Card Sortine Test (TVCST) The Wisconsin Card Sorting Test was used to assess cognitive shifting and shifting of set (Berg, 1948; Grant & Berg, 1948). This test consisted of four stimulus cards, placed in fiont of the subject, the frst with a red triangle, the second with two green stars, the third with three yellow crosses, and the fouth with four blue circles. The participant was given two packs, each consisting of 64 response cards, which had designs similar to those on the stimulus cards, varying in color, geometric form, and number. The participants' task was to place each response card in a pile below one of the four stimulus cards wherever he or she thought it should go. The participant was told by the examiner each time whether he or she was right or wrong. The participant was directed to make use of this information and try to get as many cards "right" as possible. The participant was required to sort fkst according to color, al1 other responses were called "wrong". Once 10 consecutive correct responses to color had been achieved the required sorting p~cipleshifted, without waming; color responses were now "wrong". After 10 consecutive correct responses to form, the principle shifted to number, and then back to color once more. This procedure continued until the participant had successfully completed six sorting categories (Le., color, form, number, color, form, number), or until all 128 cards had been placed.

3. Proverbs Test The Proverbs Test (Gorham, 1956) was used to assess abstract reasoning. The test was made up of 40 proverbs. Following each proverb, four choices were presented. Participants were asked to select fkom among the four alternatives, the one that best expressed the meaning of the proverb. 15 items from the test were selected for use in this study.

4. Trail Makin~Test This test was used to examine speed for visual search, attention, mental flexibility and rnotor function. It was administered in two parts. Part A consisted of a work sheet printed with 25 encircled nurnbers randornly arranged. The participant's task was to draw lines to connect consecutively numbered circles as fast as possible without lifting the pencil fkorn the paper. Part B consisted of a second work sheet on which 25 encircled numbers and Ietters were printed randomly arranged. The participant had to draw lines to connect consecutiveIy numbered and lettered circles by altemating between the two sequences as fast as possible and without lifting the pencil fiom the paper (Anny Individual Test Battery, 1944).

5. Letter CancelIation Task The letter cancellation task was used to assess visual scanning. The test consisted of a sheet of paper on which six rows of letters were printed. The participant's task was to cancel only the letters 'C' and 'E' as quickly as possible by drawing a line across it. The examiner noted the time taken to complete the test.

6. Embedded Figures Test This test was used to examine visual search and tracing of a figure embedded in the background (Spreen & Benton, 1969). This test consists of 16 straight-line drawings used as stimulus figures and presented in the lefi half of sheets of paper assembled in a test booklet. The right half of each sheet contains a complex figure drawing in which the stimulus figure is embedded. Subjects are required to search for and trace the stimulus figure in the ernbedded design using a soit pend. IV. RESULTS

For al1 tasks, the following analyses were perfomed to compare the various groups: Fint, performance of fiontal and nodiontal patients was compared to that of the control goup in order to examine whether fiontal patients (regardless of the specific fiontal region affected) differed fiom nonfiontal and control groups. This approach provides a general frontal versus posterior brain lesion differences for cornparison to other studies. Second, performance of the five focal lesion groups (l.left fiontal, 2.right frontal, 3.bifkonta1, 4.lefi postenor, and 5-right posterior) was compared to that of the control group. This provided Merspecificity regardhg the brain region involved. It allowed an examination of whether damage to a specific brain region within a hernisphere (e.g., right frontal versus right nonfrontal), as well as within the &ontal lobe (e-g., left versus right frontal region) produced an impairment in humor comprehension and production. A corollary of this approach is the investigation of the fractionation of fiontal lobe functioning and potential neural functional systems. Third, aged participants were compared to the young Finally, a modified groupkase study approach (Stuss et al., 1994) was used to examine in greater detail the specificity of lesion location in relation to the defined measures. Multiple group comparkons were performed using Kruskal-Wallis ANOVAs, while comparisons involving two groups were performed with Mann-Whitney U - Wilcoxin Rank Surn W tests. Dependent measures were specific to each task. In order to correct for multiple comparisons, when painuise comparisons were performed, a more rigid significance level was ernployed. When comparisons involved two pairs (frontal versus control group and no&ontai versus control group), a significance level of .O25 (Le., .O5 divided by the number of pairwise comparisons, which in this case, were two) was used to determine if the performance of the patient groups differed significantly f?om that of the control group. When cornparisons involved £ive pairs, Le., each of the five focal lesion groups with the control group, a significance level of -01 was used (Le., .O5 divided by the number of pairwise comparisons, which were five). Since the directed hypothesis proposed in the shidy was that patients with right frontal damage would be more impaired in humor processing, a significance level of .O5 was employed for pairwise cornparisons involving the nght frontal group with the control group. This same 88 criterion was applied to the bifiontal group since their lesion involved the right frontal region. and therefore, they could also be viewed as a part of the directed hypothesis. Also, because of the directed hypothesis, pairwise cornparisons between each focal lesion group and the control group were canied out even when overall group cornparisons (main effect of group) was not significant. Table 3 presents a summary of the results obtained kom the humor appreciation tests. Table 3 : Surnrnarv of Results on the Humor Tests Tests & Measures -F -P Funniness rat in^ Scale 1 .Mean for humor items 2.Mean for neutral items - 3.Difference score 4.Mirth responses

Joke Completion Test 1 -# of correct responses 2.Incorrect ending type (a).Hurnorous nonsequiturs (b).Straightforward (c).Associated nonsequinus 3 .Funniness raMg 4.Mirth responses Story Completion 1.# of correct responses 2,Incorrect ending type (a).Humorouç nonsequiturs (b).Associated nonsequiturs

Cartoon Rating 1 .Mean for humor items 2.Mean for slapstick items 3.Mean for associated items 4.Mean for unrelated items 5.Difference score for slapstick 6.Difference score for associated 7.Difference score for unrelated 8.Mirth responses

Cartoon Array 1 .# of correct responses 2.Fiinniness rating 3 .Mirth responses

Total Mirth Responses

Sense of Humor 1 .SeIf-rating 2.SHQ - M subscale 3.SHQ - L subscale 3.SHQ - E subscale

Production of Captions 1 Sensibility 2.Relatedness 3 .Funniness

+ indicates a signif~cantdifference in performance fiom that of the control group F = Frontal P = Postenor LF = Left fiontal RF = Right frontal BF = BiErontaI LP = Left posterior RP = Right posterior O = AgedDld Experimental Tasks: 1. Funniness Ratinp Scale: This test was used to examine appreciation of verbal humor. Three dependent measures were analyzed: 1.Mean funniness ratings assigned to humorous and neutral items in the scale; 2.Difference score, that is, the difference between ratings assigned to humorous versus neutral items; and 3.Total number of mirth responses for the task. Frontal and nonfrontal versus control groups: First, mean messratings assigned to humorous items were compared. Both the fiontal and the nonfrontal patients did not differ significantly from the control group in the mean rating assigned to humorous items. Second, mean ratings assigned to neutrd items were compared. The fiontal patients (r-2.4709; pc.0135) patients rated the neutral items as being significantly more funny than did the control group. Third, the difference scores were analyzed. The difference scores of both the fiontal and the nofiontal patients were not significantly different fiom that of the control group. Fourth, the fiontal and the nonf?ontal patients did not differ kom the control group in tems of the number of their mirth responses during the test. Focal Iesion versus control groups: Mean funnuiess ratings assigned by the different groups for the humorous and neutral items are summarized in Table 4. First, the mean furininess ratings assigned to humorous items were analyzed. ANOVAs comparing the 5 groups to the controls, as well as tests comparing each g-oup individually with the controls, al1 yielded non-significant results. That is, the patient groups did not differ f?om controls in the mean funniness ratings they assigned to humorous items.

Table 4. Performance on the Funniness Rating Scale

Group Humor Items Neutra1 Items Mirth Remonses --Mean SD Mean SD Mean SD LF 2.50 0.38 1.12 0.11 9.00 11.09 RF f .89 0.21 1.33 0.30 0.33 0.58 BF 2.36 0.53 2.39 1.07 6.00 7.75

Young 2.72 0.63 1.15 0.16 15.35 9.35 Aged 3.19 0.75 1.49 0.52 15.10 9.95 91 Similar analyses were performed to compare funnùiess ratings assigned to the neutral items. There was a significant main effect of group (chi-square=12.7828; dP5; pC.0255). Each patient group was then compared individually to the control group. The bifrontal group differed significantly tiom the control group, rating the neutral items as being significantly funnier than did the control group (r-2.8191; p<.0048). A more direct examination of the response to neutral items was to compare the difference in ratings obtained between humorous and neutral items for each participant (See figure 1). The means of the difference scores obtained by the 5 patient groups was compared with that of the control group which yielded a significant result (chi-square=l1.73 L 9; de5; pc.0387). In order to test which patient groups differed significantly from the control group, the difference scores were cornpared for each patient group with the control group. The difference in ratings assigned to humorous versus neutral items was not significantly different from the control group for lefi fiontal, lefi postenor, and right postenor groups. Only the Bght fiontal (r-2.3 795; p<.0 173) and bifiontal groups (2-2.1213; ~4.0339)differed significantly from the control group in their difference scores. This suggests that while the left frontal group was able to discriminate between humorous and neutral items, the two groups with right frontal lesion did not differentiate between the two types of items while assigning them ratings for funniness. Tnird, the number of mirth responses (srniles and laughs) exhibited during the test was summed for each participant. ANOVA was performed to compare the number of mirth responses of the patient groups with that of the control group (chi-square= 7.6126; df%; p<- 1789) which was not significant. The mirth response of each group was compared to that of the control group. Only the right frontal group differed significantly in the mean number of mirth responses (2-2.2220; pc.0263) fiom the coneol group. While the other four patient groups, as well as the control participants, demonstrated an average of 6 to 13 mirth responses while perfomiing the test, oniy one of 3 nght frontal patients tested laughed once, while the other two exhibited no mirth response at ail. The right frontal patients, therefore, demonstrated a muted emotional reaction to humorous stimuli. Aged versus young: First, the ratings assigned to humorous and neutral items were compared for the two groups. The older participants rated both the humorous (2-2.1 196; pe.0340) and the neutral (2-2.3082; p< -0210) items as funnier than did the young participants. Next, the difference scores between humorous and neutral items as well as the number of miah responses were compared. Both tests yielded non-significant results, suggesting that, aithough the older Figure 1. Difference Scores Between Ratings for Humorous and Neutra1 Items on the Funniness Rating Scale

Group 92 participants rated both humorous and neutral items as funnier than did the young, the two groups did not differ in their ability to distinguish between the two types of items, as well as their emotional reactions to them. To summarize the results of the Funniness Rating Scale, the frontal and nonfiontal patients did not differ significantly fiom the control group in tems of (a)the mean funniness ratings assigned to humorous items, @)the difference in mean rating between the humorous and neutral items, and (c) the number of mirth responses. However, the fiontal patients rated the neutral items as being funnier than did the control group. Patients with right frontal and bifiontal lesions were significantly impaired in differentiating between humorous versus neutral items compared to the control group. The right frontal group exhïbited significantly fewer mirth responses compared to control participants. Although aged participants assigned higher funniness ratings to both humorous and neutral items, they differentiated adequately between the two types of stimuli and exhibited appropriate mirth responses, indicating no impairment on this task.

2. Jokes and Storv Completion Task: Joke Completion Task: This test was used to examine two cognitive processes required for humor comprehension - surprise and coherence. Dependent measures were: 1. Total number of items correctly answered, that is, the total nurnber of items for which the original punchline (or correct funny choice - FC) was selected to complete the joke stem fiom among the four different endings presented. 2. Total number of incorrect endings of each of three types. That is, when the oriaGal punchluie or FC was not selected to complete the joke stem, the erroneous choice could be one of three ending types - humorous nonsequitur (IINS), straightforward (SF), or associated nonsequitur (ANS). The total number of errors comprishg each type was surnmed. 3. Mean of the funniness ratings assigned to correct items. 4. Total number of mirth responses observed during the test. Frontal and nonfrontal versus control groups: First, when total nurnber of errors were analyzed, only the fiontal patients differed significantly fiom the control group (2-2.5947; p<.0095). That is, the &ontal patients answered significantly fewer items correctly during joke completion. Second, the type of incorrect ending selected was analyzed. The frontal patients selected signicantly greater number of HNS (2-2.71 14; p<.0067), and SF (r-2.208 1; pc.0272) endings compared to the control group. Third, the fiontal patients rated the items they correctly 93 answered as being significantly funnier than did the control group (r-2.363 1; p<.018 1). Fourth, the frontal patients displayed significantly fewer mirth responses compared to the control group (r-2.3372; p<.0194). Focal Lesion versus control groups: Mean number of errors are summarized in Table 5 and Figure 2. First, total number of errors obtained by the different groups was analyzed. Cornparisons of each lesion group with the control group showed that only the right frontal (t- 2.3007; pC.02 14) and bifkontal (2-2.1 172; pe.0342) groups differed significantly f?om the contrai group. That is, the right fiontal and bifiontal patients completed significantly fewer joke stems with the correct hyending compared to the control group. Although the left frontal group obtained a high mean error score, this was not significantly different fiom the control group's mean score. The left fiontal group's high error score was due to a very impaired performance by one patient, while most other patients in this group performed at or very near ceiling level. Since the statistical analysis used here ranks the performance of individual participants in order to compare the groups, the scores of the lefi fiontal patients as a group did not differ f?om those of control participants. Second, the number of errors comprking each ending type were analyzed. The incorrect ending selected was grouped into one of three types (i.e., HNS, SF, or ANS), and the total number in each type was compared to the control group. The right frontal group sefected significantly greater number of humorous nonsequiturs cornpared to the control group (z- 2.61 11; p<.0090). Right fiontal patients did not differ fiom the control group in the number of SF and ANS endings chosen. That is, when nght frontal patients selected an incorrect ending to complete the joke stem, they were most attracted to hurnorous nonsequiturs, Le., slapstick endings. The right fkontal group was three times more likely to choose HNS over SF or ANS endings. The bifiontal group, the only other focal lesion group dong with the right fiontal group to make a significantly greater number of errors on this task, were more varied in the ending type selected. That is, bifiontal patients selected significantly greater numbers of HNS (2-1 -9837; p<.0473), SF (r-2.3143; p<.0206), and ANS (2-2.5686; pc.0102) ending types compared to the control group. in contrast to the right fkontal group which favored mostly HNS ending when they erred, the bifiontal patients were iikely to choose any of three incorrect ending types. Figure 2. Mean enors for Joke and Story Conditions

1 ElJoke Errors LF RF BF LP RP C f Story Errors Group . Ending LF RF BF LP RP C Type

HNS 2.00 2.33 1.50 0.33 1.O0 0.30 SF 1-50 0.67 4.50 1.O7 0.50 0.20 ANS 0.33 0.67 2.50 0.00 0.00 0.10

Storv

HNS O. 17 0.33 0.75 0.33 0.00 0.00 ANS 1.17 0.67 2.75 0.00 1.60 0.20

Third, the mean funniness rating assigned to correctly answered items was analyzed. The right frontal (2-2.0424; pc.0411) patients gave significantly greater humor ratings to the jokes compared to control participants. Fourth, the total number of smiles and laughs observed during administration of the task was analyzed. There was a significant main effect of group (chi square=11.9969; des; p<.0348). Similar to the Funniness Rating Scale, right frontal patients demonstrated significantly fewer (none) mirth responses (r-2.1018; p<.0356) compared to the control group. On this task, bifiontal patients also had significantly fewer mirth responses (r-2.3 693; pc.0 178). Aged versus Young: Performance of the young and aged groups is summarized in Table 6. First, the aged group made significantly more errors (r-2.2926; pc.0219) compared to the young group. Second, when they erred, aged participants selected significantly greater number of HNS (2-2.9984; pe.0457) and SF (2-2.0266; pc.0427) endings compared to young participants. Third, the aged group assigned significantly higher funniness ratings to the items they answered correctly compared to the young group (2-2.1659; pc.0303). Fourth, aged participants exhibited significantly fewer mirth responses on this task compared to the young participants (2-2.1529; Table 6.Joke and Stow Completion Task: Mean Errors for Young and A~edGroups

Ending Type Young Aged

Joke

HNS SF ANS

Total SD

HNS ANS

Total SD

To summarize the results of the Joke Completion Task, the gontal patients obtained significantly fewer items correct, assigned higher funniness ratings to correct items, and displayed fewer mirth responses cornpared to the control group. When the frontal patients failed to pick the correct punch line to complete the joke, they selected significantly greater numbers of HNS and SF endings. The nofiontal patients did not differ fiom the control group on any measure. Right fiontal and bifrontal groups made significantly more errors on the Joke condition cornpared to the control group. Analysis of the pattern of their errors revealed that the nght frontal group, when they erred, seiected significantly greater number of humorous non sequiturs (ENS), while the bifiontal group chose al1 three erroneous ending types, i.e., HNS, ANS and SF. Right fiontal and bifkontal patients exhibited significantly fewer mirth responses. The left fiontal group's performance was not different kom that of the control group. The aged group obtained significantly fewer items correct and when they erred, chose HNS and SF endings compared to young participants. The elderly assigned higher funniness ratings and exhibited significantly fewer mirth responses. 96 Storv Completion Task: This test was used in conjunction with the Joke Completion test to assess narrative ability and the ability to apply the surprise and coherence requirements appropriately in narrative tasks. Dependent mesures were: 1. Total number of items correctly answered, that is, the total number of items for which the straightfonvard ending was selected as the correct choice to complete the short story stem. 2. For incorrect items, the total number of items comprising each of the hwo incorrect ending types, Le., HNS and ANS endings. Frontal and nonfrontal versus control groups: First, when the correct items was analyzed, both the fkuntal (r-2.3453; p<.0190) and the nonfiontal (z-2.3260; pC.0200) patients obtained significantly fewer correct items compared to the control group. Second, the type of incorrect ending selected was andyzed. Neither group differed significantly fkom the control group in the type of erroneous ending selected. Focal lesion versus control groups: First, the number of errors made by each group was analyzed. BiErontal (2-2.3 143; pc.0206) and nght posterior (r--2.8983 ; pc.003 8) groups obtained a significantly fewer number of correct items compared to the control group. Next, the incorrect ending type selected was analyzed. Bifiontd patients, when they selected an incorrect ending, chose significantly greater number of HNS (r-2.3205; p<.0203), as well as, ANS (z- 2.1555; p<.03 11) endings compared to control participants. In contrast, right posterior patients when they erred, chose only ANS endings (r-2.8983; p<.0038) and cornpletely refrained fkom selecting HNS endings. This shows that right postenor patients realized the inappropriateness of a slapstick ending while completing the stury task. Aged versus young: First, aged participants did not differ significantly fiom young participants in number of story items correctly completed. The aged group, therefore, did not differ fkom young participants in the number of incorrect endings (HNS and ANS) chosen. To summarize the results of the Story Condition, both the fiontal and the nonfkontal patients scored significantly fewer correct items cornpared to the control group. Bifrontal and ight posterior groups made more errors compared to the control group. Bifkntal patients chose significantly greater number of HNS and ANS endings when they erred, while right posterior patients selected only ANS endings. The aged group did not differ significantly from the young IzrOuP- 3. Cartoon Ratinp Test: This test was used to assess appreciation of cartoon humor. Dependent measures on the test were: 1.Mean funniness rating assigned to each of the four types of stimuli used in the task - humorous captions, slapstick captions, associated captions, and unrelated captions. 2-Three difference scores obtained fiom computing the difference between ratings assigned to humorous items versus slapstick, associated, and unrelated captioned items. 3.Total number of mirth responses observed during the task. Frontal and nonfrontal versus control groups: First, the mean funniness rating assigned to each of the four types of stimuli was analyzed. Both the frontal and the nonfiontal patients did not differ significantly from the control group in terms of their funniness ratings for humorous, slapstick, associated, and unrelated captioned stimuli. Second, the difference scores were analyzed. The frontal patients' difference scores were significantly different fiom those of the control group's for slapstick (z-2.2 104; p<.0271) and unrelated captioned (2-2.2477; pc.0246) stimuli. This indicates that, although the frontai patients assigned comparable ratings to that of the control group for al1 stimulus types, they failed to differentiate sufficiently between the truly humorous items and the foils. Third, both the fkontal and the nonfrontal patients did not differ significantiy fiom the control group in terms of their mirth responses. Focal lesion versus control groups: Mean funniness ratings assigned to the humorous and foi1 items by the various groups are presented in Table 7. First, multiple group comparisons, as well as paired group comparisons of the five patient groups with the control group for mean funniness rating assigned to humorous items were perfonned. None were significant suggesting that focal lesion patients did not differ from the control groups in hinniness ratings assigned to humorous items. Similar analyses were perforrned for mean ratings assigned to slapstick items. Only the bifiontal group differed significantly, that is, they rated the slapstick items as being funnier than did the controls (z- 2.0643; pc.0390). Results were sirnilar for mean ratings assigned to items with associated captions, Le., only the bifkonta.1 group rated these items as being funnier than the controls did (2-2.5540; pc.0106). For items with unrelated captions, none of the comparisons were significant, that is, none of the patient groups differed in their mean funniness ratings fiom the control group. Therefore, analyses of the mean funniness ratings assigned to the four types of stimuli showed that only the bifiontal group significantly rated slapstick and associated items as being funnier than the control group did.

Table 7. Mean Funniness Rating for Humorous Cartoon Items and Foils

Group Hurnor Associated Unrelated

Mean SD Mean SD Mean SD LF 2.46 0.45 1.35 0.46 1.31 0.37 RF 1.96 0.38 1 0.19 1-08 0.07 BF 2.34 0.51 2.31 0.44 1.81 0.48

LT 2.75 0.33 1.50 0.00 1.46 0.51 RT 2.28 0.61 1.55 0.76 1.25 0.49 C 2.63 0.56 1.40 0.42 1.20 0.34

Young 2.34 0.65 1-26 0.24 1.14 0.20 Aged 2.87 0.77 1.64 0.59 1.44 0.46

Second, difference scores were analyzed to examine whether participants could differentiate sufficiently between hurnor items versus the three types of foils (Le., slapstick, associated and unrelated captions) in terms of their funniness ratings. Multiple as wel as paired group comparisons with the control group, using difference scores between humorous and slapstick items were not significant, suggesting that al1 groups were able to differentiate between these two types of stimuli. Similar analyses for difference scores between humorous and associated captioned items showed a significant main effect of group (chi square=13.8807; d+5; p<.0164). individual group cornparisons with the control group were significant for the bifrontal group (r- 2.4148, p< .0157). That is, bifkontal patients did not differentiate sufficiently between humorous and associated caption items. None of the comparisons was significant for difference scores between humorous and unrelated caption stimuli. Third, total nurnber of mirth responses observed during the task were anaiyzed. As in the Funniness Rating Scale, only right fiontal patients differed significantly fkom the control group, exhibiting virtually no physical reaction (r-2.3205; p<.0203). Aged versus Young: First, mean funniness ratings assigned for the four different types of stimuli were analyzed. Older participants gave significantly higher mean fùnniness ratings for humorous captions (2-2.33 72, pC.0 194), associated captions(=Z ,2027, p<.0276), and unrelated captions (2-2.4424, pt0146). That is, except for slapstick items, the aged participants rated the stimuli as being funnier than the young participants did. 99 Second, difference scores were analyzed, which were significant only for slapstick stimuli (r-2.1601; pc.0308) suggesting that the aged participants did not differentiate sufficiently between humorous and slapstick stimuli. Third, mirth responses were analyzed. The two groups did not differ significantly in terms of the nurnber of mirth responses exhibited during the task. To summarize the results of the Cartoon Rating Task, the fiontal patients assigned funniness ratings comparable to those assigned by the control group for al1 four stimulus types. However, they failed to distinguish adequately behveen the humorous items and some foiis in terms of the difference scores. The nonfrontal patients did not differ significantly £kom the conb-01 group on any measure. Of the focal lesion groups, only bifiontal patients were confused by the foils, rating items with slapstick and associated captions as being funnier than did the control group. Bifkontal patients did not distinguish adequately between humorous and associated captioned items in terms of their funniness ratings as measured by the difference scores. Right fiontal patients demonstrated virtually no mirth responses, diffenng significantly f?om the conml group. Aged participants gave higher funniness ratings to items with humorous, associated, and unrelated captions compared to the young group. The aged participants did not distinguish adequately between humorous and slapstick captions in terms of the difference scores.

4. Cartoon Arrav Task: This test was used to examine the ability to attend to visual detail that is required for cartoon humor. Dependent measures were: 1. Number correct, that is, the total nurnber of items for which the cartoon drawing with the humorous detail was selected as the funniest cartoon fiom arnong four choices. 2. Mean funniness rating assigned to correct items. 3. Total number of mirth responses exhibited durhg administration of the task. Frontal and nonfrontal versus control groups: First, total number of correct items were analyzed. Both the frontal (2-3.3871; p<.0007) and the nonfkontal (2-2.3451; p<.0190) patients obtained significantly fewer correct items compared to the control group. Second, the fiontal patients assigned higher funniness ratings compared to the control group for the items they answered correctly (2-3.0767; pc.0021). Third, both the fiontal and the nonf?ontal patients did not differ significantly firom the control group in the number of rnirth responses. 100 Focal lesion venus control groups: Performance of the various groups is presented in Table 8. First, total number of correct items obtained by the different groups was analyzed. There was a main effect of group (chi-square=15.1882; pc.0096). Cornparisons between each patient group with the control group revealed that left fiontal (r-3.0910; p<.0020), right frontal (r-2.7790; pc.0055) and right posterior (z-2.87 12; p<.OO4 1) groups obtained significantly fewer number of correct items.

Table 8. Mean Number of Errors on the Cartoon Array Task

Group Mean -SD LF 2.33 2 .O3 RF 3 -67 2.89 BF 4.50 3 .O0

Young 0.53 0.62 Aged 2.75 1.45

It seemed strange that bifiontal patients did not differ significantly fkom the control group, while left fiontal and right fiontal patients did. Inspection of raw data showed that this was due to one bifiontal patient (with a very small lesion) who obtained a perfect score, while al1 other bifiontal patients performed very poorly. Therefore, results were fùrther analyzed. A 't' test comparing the mean number of correct items between al1 bifiontal patients and control participants was sigrificant (F=16.204; pc.002). Repeat analysis comparing the bifrontal group with the control group after removing the results of the individual with the perfect score was also significant (-2.7928; pc.0052). Therefore, the bifiontal group's performance was significantly impaired compared to the control group. Second, mean fiinniness rating assigned to correct items was analyzed. There was a significant main effect of group (chi-square=14.7900; pc.0 113). Individual group comparisons with the control group revealed that left frontal (2-2.5584; p<.0105) and bifkontal (2-2.4148; pC.0 15 7) group gave higher funniness ratings compared to the control group. Third, number of mirth responses were analyzed. Neither multiple nor paired group comparisons were significant. (Right fkontal patients exhibited no mirth responses. But this 101 failed to reach significance (r-1.8841; p<.0596) because other patient groups, as well as. the control group exhibited fewer mirth responses compared to other humor tasks). Aged versus young: First, aged participants scored significantly fewer correct items compared to the young participants (2-4.5246; p<.0000). Second, the aged group did not differ frorn the young group in their rnirth responses. Third, aged participants assigned significantly higher hinniness ratings to the correct items compared to young participants (2-2.0434; p<.O4lO). To summarize the results of the Cartoon Array Task, both the fiontal and the nonfiontal patients obtained significantly fewer number of correct items compared to the control group. Left ftontal, right fiontal, bifkontal, and right posterior groups obtained si,gnificantly fewer correct items compared to the control group. Aged participants obtained significantly fewer comect items and assigned higher funniness ratings compared to young participants.

Total Number of Mirth Res~onses: Since the number of mirth responses exhibited by some patient groups differed significantly frorn that of the control group on some tests, the total number of mirth responses displayed by the patient groups was analyzed. This was based on the sum of the mirth responses recorded during the administration of the following hurnor appreciation tests: (a)Funniness Rating Scale, (b)Joke Cornpletion test, (c)Ca.toon Rating test, and (d)Cartoon Array test. Frontal and nonfrontal versus control groups: Neither the fiontal nor the nonfrontal group differed significantly fÏorn the control group in the total number of mirth responses. Focal Lesion versus control groups: Multiple group comparison of the total number of mirth responses of the five focal lesion groups to the control group was not significant. However, painvise cornparisons of each focal lesion group with the control group showed that only the right fiontal group (2-2.5355; pc.0112) differed fiom the control group, exhibithg significantly fewer rnirth responses during the administration of the hurnor appreciation tests. That is, only the right fiontal patients demonstrated muted physicaYemotiona1 reactions during the humor testing.

5. Sense of Humor: This was used to examine the patients' ability to make self-evaluations regarding their own sensitivity to humor and humorous situations. Dependent rneasures were: 1. Self-ratings by each 102 participant regarding hislher own sense of humor on a Il-point rating scaie. 2. Mean score obtained by each group on the three subscales of the Sense of Humor Questionnaire, Le., (a) metamessage sensitivity (M), (b) persona1 liking of humor (L), and (c) emotional permi- ssiveness (E). Frontal and nonfrontal versus control groups: First, only the frontal patients rated themselves as having a lower sense of humor compared to the control group (2-2.5 152; pe.0 1 19). Second. only the fiontal patients obtained a significantly lower score on the metamessage sensitivity (M) subscale of the Sense of Humor Questionnaire (2-2.7801; p<.0054) indicating that they may have a reduced ability to recognize humor in situations. Neither the fkontal nor the nonfiontal patients differed significantly from the control group in terms of their scores on the L and E subscales of the SHQ. The nonfrontal patients did not differ fiom the control group on any rneasure. Focal lesion versus control groups: The mean self-rating assigned by the various groups is shown in Table 9.

Table 9. Mean Self-ratin3 for Sense of Humor Group Mean -SD LF 6.83 1.47 RF 5 .O0 2.65 BF 4.75 1.89 LT 7.33 1.15 RT 7.20 2.17 C 7.80 1.14

Young 6.53 2.35 Aged 6.65 1.69

Cornparisons of each lesion group with the control group showed that nght fiontal (z- 2.2087; pc0272) and bifiontal(z=-2.95 10; pc.0032) patients rated themselves as having a lower sense of humor than did the control participants. Mean scores obtained for the subscales of the Sense of Hurnor Questionnaire were assessed. These are shown in Table 10.

(a) Right frontal (2-2.4924; pC.0127) and bifiontal (2-2.0876; pc.0368) groups obtained a significantly lower mean score for metamessage sensitivity (M), suggesting they may have a 103 reduced ability to recognize humor in situations. @) None of the lesion groups differed from the control group in mean scores obtained for persona1 Wùng of humor (L), or the enjoyment of hurnor and the humorous role. (c) There were also no significant differences in mean scores obtained by the patient groups compared to the control group on emotional permissiveness (E). or the tendency to fieely express one's emotions.

Table 10. Mean Scores on the Subscales of SHO

Group SHQ-M SHO-L SHO-E Mean SD Mean SD Mean SD LF 5.17 3.37 -16.17 3.87 9.00 3.74 RF 2.33 2.52 -16.67 2.52 7.33 3.79 BF 4.75 2.87 -15.75 2.87 8.75 1.71

Young 5.59 2.83 -12.18 3.17 7.24 2.28 Aged 4.84 2.80 -14.20 3.37 7.10 2.17

Aged versus young: The aged and young participants did not differ significantly in their self-ratings regarding own sense of humor. The two groups also were not significantly different on mean scores achieved on the three subscales of the Sense of Hurnor Questionnaire. To summarize the results on sense of humor, the fiontal patients obtained a significantly lower self-rating for sense of humor, as well as, a significantly lower score on the M subscale of the SHQ compared to the control group. Right fiontal and bifiontal patients rated themselves as having a significantly lower sense of humor compared to control participants. On the Sense of Humor Questionnaire, nght fiontal and bifiontal groups obtained significantly lower mean score for metamessage sensitivity subscale, suggesting they may have a reduced ability to recognize humor in situations. The aged group did not differ fiom the young group in self-ratings for sense of hurnor or on any of the subscales of the SHQ.

6. Production of Captions:- Scanne of Carrtions: The verbal captions produced by each participant were rated by three scorers individually on the following measures: 1. Sensibility, i.e., whether the verbal captions made sense, 2. Relatedness, i-e., wheîher the verbal caption was related to the picture (was relevant), and 3. Funniness. The following rating scale was used to score each of the measures: I - Not Sensible / Related / Funny; 2 - Slightly Sensible / Related / Funny; 3 - Quite Sensible / Related / Funny; 4 - Very Sensible / Related / Funny; and 5 - Extremely Sensible / Related / Funny. The scores assigned by the three raters individually were then averaged for each caption, for each of the three rneasures. These scores for each caption were then averaged across the task for al1 captions produced. Thus, each participant obtained three mean scores - (a) mean sensibility score, (b) mean relatedness score, and (c) mean fùnniness score, taking into account al1 the verbal captions produced by that participant. Dependent measures were: 1. Mean sensibility score, 2. Mean relatedness score, and 3. Mean fiuininess score. Frontal and nonfrontal versus conho1 groups: The frontal patients obtained significantly lower mean sensibility score (2-2.5799; p<0.0099) compared to the control group. The fiontal patients did not differ significantly fkom the control group in terms of their mean relatedness or fùnniness scores. The nonfiontal patients did not differ significantly f?om the control group on any measure. Focal lesion versus control group: Mean ratings obtained by the various groups for their captions is presented in Table 1 1.

Table 1 1. Mean Ratines for Production of Captions gr ou^ Sensibilitv Relatedness Funniness Mean SD Mean -SD Mean -SD LF 3.38 0.22 3.15 0 -45 1.65 0.43 RF 3.50 0.44 3.47 0.35 1.70 0.46 BF 3.45 0.06 3.20 0.24 1.50 0.35

Young 3.60 0.25 3.38 0.24 1.94 0.3 9 Aged 3.43 0.35 3.16 0.43 1.73 0.3 1

First, when mean sensibility scores were examined, there was a main effect of group (chi- square=11.1439; pC.0486). Cornparisons of each patient group with the control group revealed 105 that lef? fiontal (r-2.4942; pc.0 126) and bifrontal (r-2.1847; p<-0289) groups obtained lower scores for sensibility. Second, there was no signîficant difference between any of the lesion groups and the control group on scores for relatedness. Third, bifkontal patients scored significantly lower than the control group for fiinniness of captions produced (z-2.0597, pc.0394). Aged versus young: Older participants did not differ significantly 50m young participants on any of the three measures, Le., mean scores for sensibility, relatedness, or fünniness. To summarize, the fiontal patients obtained significantly lower mean sensibility score for captions compared to the control group. The captions produced by the lefi frontal and bifiontal groups were rated as making significantly less sense compared to those produced by the control group. Captions created by the bifiontal group were rated as being significantly less funnier than those of the control group. Ratings for captions produced by the aged group did not differ significantly frorn those of the young group on any measure.

7. Production of Humor: Two tasks were used to assess production of hurnor - a)Tell a joke, and b)Read jokes. A11 participants were videotaped while performing these two tasks. a) Tell a Joke: This task was used to assess joke-telling ability and memory for old humor. Participants were requested to tell any joke that they knew. Al1 participants had been informed at the beginning of the test session that they would be asked to tell a joke later during the test session. They had approximately 1-5 to 2 hours, although other tasks were being administered, to think of a joke and keep it in mind to be recounted later when asked. Many participants were unable to produce a joke, despite the advance notice and prompts. The proportion of participants who failed to produce jokes in each group is shown in Table 12. Table 12. The proportion of participants who failed to produce a ioke in each oroup gr ou^ Proportion

Since the number of participants who produced jokes is very small in some patient groups, data were not subjected to statisticd analyses. Results of these two tasks, Tell a Joke and Read Jokes, are therefore only presented descnptively. Scorin~of Tell a Joke: Two raters were used to score each participant's telling of a joke. The two raters watched the videotapes of the participants' telling of a joke and rated them on a number of measures. Each rater's score was independent of the score of the other rater. A note was made of whether participants smiled before, during, and &er telling the joke, as well as, time to onset of joke afier instructions to recount a joke. Mer a joke was narrated, it was rated on the following measures - 1. Directness, whether joke waç told directly, 2. Punchline, whether an obvious punchline was present, 3. Surprise, whether sufficient background information was provided so that the punchline would evoke surprise when it was presented, 4. Coherence, whether the punchline provided could be reconciled with the body of the joke to establish coherence, 5. Logic, whether the joke and its telling were logical, and 6. Funniness, how humorous or funny the joke-telhg was, Le., overall success in telling the joke. Each of these measures were rated on a 5-point scale independently by each of the two raters while watching the videotape of the participant telling the joke. On the 5-point rating scale, a rating of 1 indicated absence of the feature being rated. For instance, a rating of 1 on all measures would indicate that the joke telling was not direct, there was no obvious punchline, no surprise was set up, the punchline did not establish coherence, was not logical, and was not funny. In contrast, a rating of 5 on al1 of the above measures would indicate that the joke telling was extremely direct, an obvious punchline was present, the set up for surprise was extremely obvious, the punchline easily established coherence with the body of the joke, the joke and its telling were extremely 107 logical, and that the joke was extremely funny. The score for each rneasure was the mean of the rating given by the two raters. Results of Tell a Joke: First, some participants were unable to produce a joke, despite being given advance notice and prompts / cues. Except the left fiontal group, in every other patient group, as well as the conwol group, at least one participant claimed to be unable to recall any joke. This was especially the case with right frontal and bifkontal groups. That is, a greater proportion of right fiontal and bifkontal patients failed to produce any joke. Second, when participants narrated a joke, it was generally accompanied by smiling before, during, and after the joke was told, in al1 groups. Third, the joke that was produced was rated in tenns of the six measures described above. 1. Directness: The jokes produced by the right fiontal group obtained a low rating for directness. 2. Punchline: The jokes narrated by the nght fiontal and bifkontal patients obtained lower rating for having an obvious punchline. 3. Surprise: The nght fiontal and bifkontal patients obtained lower ratings for provision of suflicient background information in the joke so that the punchline could evoke surprise when presented. 4. Coherence: Right frontal and bifkontal patients were rated lower for coherence, that is, their punchline could not be reconciled with the body of the joke. 5. Logic: Jokes told by the nght fkontal and right temporal patients obtained lower ratings for being logical. 6. Funniness: Right fiontal, bifkontal and nght temporal patients obtained the lowest ratings for funniness of the jokes they recalled. To summarize the results of Tell a Joke, a greater propomon of right fiontal and bifiontal patients were unable to produce any joke. The jokes recalled by the nght fiontal and bifi-ontal patients obtained lower ratings on most rneasures, that is, they were rated as being less direct, having no obvious punchline, failing to set up background information to evoke surprise, unable to establish coherence of the punchline with the body of the joke, less logical and less fùnny compared to other groups. b) Read Jokes: Participants were instructed to read three short stones which were jokes. They were not aware at first that they were reading jokes, but would 'catch on' after reading the first or second joke. The reading of the jokes were scored by two raters on a 5-point scale for: 1. Containing appropnate humorous prosody and intonation, and 2. Success in reading of the joke, i.e., success in conveying the humor. 108 For reading of the fist joke, bifiontal patients obtained the lowest rating for humorous prosody and intonation, while the right fiontal and bifiontal patients were rated as being less successfbl in reading. For the second joke, generally al1 groups obtained higher scores compared to the first joke in rating for humorous prosody and intonation. Right fi-ontal and bifiontal patients still obtained the lowest ratings for success in reading of the joke. By the third joke, there was a marked improvement in prosody and intonation in al1 groups compared to reading of the first joke, including the right fiontal and bifiontal patients. Left frontal, right frontal and bikontal obtained the lowest scores for success in telling of the third joke.

Factor Analvsis of Humor: Humor consists of different types, which are associated with different psychological processes. Factor analysis was performed in order to simplify the data and identifi a smaller number of factors that rnight represent the relationships among the variables obtained fiorn the various hurnor tests. Only the scores of the normal subjects tested in the study (matched controls, young nomals, and aged, N45)were used in obtaining the factors in order to examine the constnicts/ dimensions underlying humor appreciation and production in a normal population. Six variables were selected kom the measures obtained fiom the different humor tests for their inclusion in the factor analysis. These were thought to be representative of performance on humor appreciation and production. These six scores were: (1)the total mirth score (the sum of the nurnber of srniles and laughs recorded on al1 humor appreciation tests, Le., the Funniness Rating Scale, the Joke Completion test, the Cartoon Rating test, and the Cartoon kray test; (2)the difference score from the Funniness Rating Scale (the difference in funniness ratings for humorous versus neutral items); (3)the number of correct responses on the Joke Cornpletion test; (4)number correct on the Story Completion test; (5)the nurnber of correct choices on the Cartoon Array test; and (6)ratings for funniness on the Production of Captions test. Factor extraction procedure using principal components analysis produced two factors. Factor 1 was composed of variables 3, 4, 5, and 6 (i.e., the nunber of correct responses on the Joke Completion test; number correct on the Story Completion test; the nurnber of correct choices on the Cartoon Array test; and ratings for funniness on the Production of Captions test). Factor 2 was made up of the remaining two variables, the total mirth score and the Funniness Rating Scale difference score. 109 Factor 1 can be interpreted as a measure of humor detection and production. representing the cognitive dimension of humor. Factor 2, composed of the total mirth responses and the Funniness Rating Scale difference score might be interpreted as measuring humor appreciation or the affective dimension of hurnor.

Frontal / Concurrent Processes Tasks: A number of tasks were adrninistered to measure a variety of psychological processes which were thought to be posçibly associated with the ability to appreciate humorous stimuli. For each group (fiontal, nonfiontal and control), scores on these tests were correlated with that of specific humor tasks in order to investigate whether the psychological processes measured by these tasks contributed significantly to performance on humor tasks. Spearman Rank Order Correlations were computed between scores on tasks measuring different psychological processes and scores on humor tests. Because the number of correlational analyses perfomed was large, an arbitrary criterion was selected to decide which correlations would be accepted as significant. It was decided that the r value itself must exceed .5 and, in addition, must also exceed the -025 significance level.

1. Beck's Depression Inventorv: BDI was used to screen for depression in order to ensure that the depression often expenenced by patient groups did not unduly influence their performance on the humor tests. By the criteria outlined above, none of the correlations between the BDI scores of the various groups and perfomance on the humor tasks were significant. This suggests that the depression levels of the participants did not significantly affect their performance on the humor tasks.

2. Workinp Mernom: The Alpha Span task was employed to obtain a measure of working memory in order to investigate its contribution to the ability to complete joke stems. A score was obtained for each participant by weighting each correct response by the string length and then obtaining their sum. Dependent measure was the score obtained by each participant. The scores obtained on the Alpha Span test were correlated with the number of errors on the Joke Completion test and the Cartoon Array test. 110 For the fiontal patients, there was a significant correlation between the scores on the Alpha Span task and the number of errors on the Joke Completion task (r--74; p<.00). This was also significant for the nodiontal patients (r-32; pc.02). For the control group, the correlation between these two tests was not significant. For the frontal and nodonta1 patients, the poorer the performance on this working memory task, the greater the number of errors on the Joke Completion task. This suggests that working memory may influence the ability to select the appropriate punchline to complete a joke stem. There was ais0 a significant correlation between scores on the Alpha Span test and number of correct responses on the Cartoon Array task (r=.70; pc.007). This indicates that better working memory, as measured by the scores on the Alpha Span test, is associated with better performance on the Cartoon Array task. There was a significant correlation in fiontal lobe patients between the time taken to complete Part B of the Trail Making Test, a measure of cognitive shifing and working memory, and the number of correct responses on the Joke CompIetion test (F-.64; pc.025). The longer the tirne taken to complete this task, the lower the number of correct responses on the Joke Completion test. For patients with fiontal lobe lesions, there was a significant correlation between the number of errors on the Cartoon Array task and the tirne taken to cornplete Part B of the TraiI Making Test (r=.65; p<.02), indicating that this working memory measure was related to successfûl performance on the cartoon test. The significant correIations between the two measures of working memory (Alpha Span and Part B of the Trail Making Test) and the two humor tests indicate that working memory is related to both verbal and nonverbal humor comprehension. For elderly participants there was a significant correlation between the number of errors on the Joke Completion test and Alpha Span test (r-.61; pc.004), as well as the time taken to complete Part B of the Trail Making Test (17497; pt007). These correlations indicate that working memory was related to the ability of the elderly participants to select appropriate punchlines for jokes.

3. Proverbs Test: The Proverbs test was used to assess quality of thinking or abstract verbal reasonùlg (Lezak, 1983), since this was considered to be essential for the comprehension of verbal humor which are 111 also made up abstract verbal items. Dependent measure was the number of items correctly answered on the multiple-choice Proverbs test. The scores on the Proverbs test was correlated with the number of errors on the Joke Completion test. For the fiontal patients, there was a significant correlation between the scores on the Proverbs test and the number of errors on the Joke Completion test (p.74; pc.00). That is, poorer abstract verbal reasoning abilities in the frontal patients, as measured by the Proverbs test. was associated with poorer performance on the Joke Completion test. For the nonfrontal and control participants, the correlations were not significant.

4. tetter CanceIlation: The Letter Cancellation test was employed to investigate visual scanning and focused attention, and their contribution to success on the Cartoon Amay task. Dependent rneasures were: 1. Total time taken to cornplete the task, Le., to cancel al1 C's and E's on the sheet, and 2. Total number of errors, i-e., the sum of wrong cancellations (letters other than C and E that were cancelled) and omissions (C's and E's that were not cancelled). The two dependent measures were correlated with the number of errors on the Cartoon Array test. For the fiontal patients, there was a significant correlation between the total time taken to cornplete the Letter Cancellation test and the nurnber of errors on the Cartoon Anay task (F-82; p<-00). For the fiontal patients, the correlation between the number of errors on the Cancellation test and performance on the Cartoon Amay task was also significant (r=.66; pC.01)- These correlations suggest that for the fkontal patients, the length of tirne taken to perforrn visual scanning and the number of errors cornmitted on the cancellation test was associated with their ability to scan, attend to, and focus on relevant and cntical visual details in the cartoon array. The correlations between the dependent measures of the cancellation test and the cartoon array task were not significant for nonfrontal and control participants.

5. Trail Makinp Test: The Trail Making Test was used to assess speed of visual search and attention, as well as, cognitive flexibility and working memory, in order to investigate their eflect on the ability to search and focus on relevant details necessary for successfül performance on the Cartoon Array task. Dependent measures were: (1) Total time taken to cornpiete Part A; (2) Number of errors on Part A; (3) Total time taken to complete Part B; and (4) Number of errors on Part B. 112 Performance on the Trail Making Test were correlated with the number of erros on the Cartoon Array task. Part A of the test, a measure of simple speed, was not related to the humor measure. There was a significant correlation for the frontal patients, between the number of errors on the Cartoon Array task and the tirne taken to complete part B (~65;p<.02). This suggests that the time taken to complete part B of the Trail Making test, a measure of visual search and attention. as well as workîng memory and cognitive flexibility, had an impact on the performance on the Cartoon Array task in fiontal patients. There were no significant correlations between the dependent measures of the Trail Making test and the cartoon array task for nonfiontal and control participants.

6. Embedded Fipures Test: nie Embedded Figures test was also used to examine visual search and its effect on performance on the Cartoon Array task. Dependent measure was the total number of items completed correctly on sections 2 and 3 of the test. Scores obtained on the Embedded Figures test were correlated with the number of errors on the Cartoon Array task. For the kontal group, there was a significant correlation between the number of errors on the Cartoon Array task and the score on the Embedded Figures test (r--76; pc.00). That is, the higher the score on the Embedded Figures test, the lower the number of errors on the Cartoon Array task. ln other words, for the fiontal patients, the better the visual search and ability to separate figure f?om ground as rneasured by the Ernbedded Figures test, the better the performance on the Cartoon kray task. For the nonfkontal and control participants, the correlations between the scores on the Embedded Figures test and the errors on the cartoon array task were not significant.

7. Jud~mentof Line Orientation: Dependent measure was the total score obtained for each participant which was the number of correct responses on the task, corrected for age and sex. The scores on the Judgment of Line Onentation test were correlated with the number of errors on the Cartoon Array task. The correlations between the performance on the Judgment of Line Onentation test and the number of errors on the Cartoon Array task were not significant for any group, Le., fiontal, nonfiontal, or control. This indicates that simple visual perception or visual recognition was not related to performance on the Cartoon Array test.

8. Wisconsin Card Sortine Test WCST): This test was used to assess ability to shift or flexibility of thinking and problem solving which we hypothesized to be essential in order to establish coherence of the punchline with the body of the joke, as indicated by the Incongmity-Resolution mode1 of humor cornprehension. The dependent measure was the number of categorïes achieved on the WCST, which was correlated with the number of errors on the Joke Completion test. The correlation was significant only for control participants (F-.89; pc.00)-

Summarv of Correlational Analyses Between Humor Tests and Tests Measurinp Frontal / Concurrent Processes: To identiQ fùrther the processes underlying humor appreciation, performance on several neuropsychological tests were correlated with performance on humor tests. The neuropsychological abilities did correlate in a logical manner with performance on specific hurnor tests. Working memory was associated with the abiliv to complete a joke stem by choosing the correct punch line from a multiple choice array on the Joke Completion test for both fiontal and nonfkontal patients. Abstract verbal reasoning ability, as measured by the Proverbs test, was associated with comprehension of verbal hurnor on the Joke Completion test. Visual scanning, ability to attend and focus on visual stimuli was associated with the ability to attend and focus on the relevant critical detail providing humor in a cartoon. For the frontal patients, performance on tests examining these perceptual processes, Le., Letter Cancellation, Trail Making, and Embedded Fi,wes, was significantly correlated with the number of errors on the Cartoon Array test. This pattern of associations between psychological processes and humor indicate some of the underlying mechanisms involved in the appreciation of humor. 114 Specificitv of Lesion Location Grouping patients by gross anatomical regions, while the most common approach in group brain-behavior studies, does not address the potential specificity of localization of fiontal lobe functioning. To address this issue, we used the behavioral performances as the criterion to differentiate the patients fiom the normal control participants. The two measures that had revealed most significant differences on the original fiontal groupings were used: @)the difference score (Le., the difference in funniness rating between humorous and neut~alitems) on the Funniness Rating Scale, and @)the number of correct items on the Joke Completion test. Group A consisted of poor performers, i.e., a11 fkontal lobe patients (right, lefi, and bilateral) whose scores fell one standard deviation below that of the control participants' scores on both rneasures. Group B consisted of good performers, i.e., al1 fiontal lobe patients whose scores were within one standard deviation of that of normal control participants. Performance of the Group B was, therefore, comparable to that of the control participants on the selected tests. Two procedures were then used to rehe the brain-behavior relationship. First, al1 the lesions within each group were superimposed (See Figure on page 116). The anatornical differentiation was obvious. The patients who were non-irnpaired on the humor appreciation tests (Group B) al1 had lesions largely restricted to the lefi fiontal lobe. Most patients who were impaired (Group A) had lesions involving the right frontal region, involving superior, roshal, primarily polar regions, particularly areas 8 and 9. The relevance of media1 versus iateral pathology in this area cannot be dissociated with our curent group of patients. Thus, damage to the right supenor, anterior/ polar regions of the frontal lobe produced impairments in humor appreciation. These new anatomical groups were then compared on the humor rneasures. Nonpararnetric ANOVAs were used to compare the performance of these fiontal Groups A and B to that of control participants on the major variables obtained fiom the humor tests. Group A differed significantly compared to the control participants on the following variables: (1) the difference in fi.mriiness rating between humorous and neutrd items on the Funniness Rating Scale (2-3.0935; pc.002); (2) the number of correct responses on the Joke Completion test (2-3.4078; p<.0007); (3) the number of correct responses on the Cartoon hytest (-3.41 88; pc.0006); (4)the total number of mirth responses during the administration of the humor appreciation tests (2-2.9938; p<.0028); (5)the mean self-rating for sense of humor (-3.0645; pc.0022); and (6)the mean funniness rating assigned by raters for the captions produced on the Productions of Captions test (2-2.5 132; pC.0 12). 115 Group B did not differ significantly fiom the control participants on any of the above measures. These new anatomical groups led to a greater dissociation of humor appreciation. These results suggest not only a rekernent of the finding of the importance of the right hemisphere to humor, emphasizing the role of the right frontal lobe, but a possible even finer distinction within this right fkontal region. The localization of pathology involving the antenor/polar region of the right frontal lobe in producing a humor deficit is in apparent contrast with previous research by Brownell et al. (1983) and Bihrie et al. (1986). In these earlier studies, right hemisphere patients who were impaired on humor tests typically were those with pathology invoiving the middle cerebral artery and, therefore, had more posterior frontal pathology if the frontal lobes were included. However, the pattern of impairment on the Joke Completion test was comparable for these patients to that observed in the present group. This suggests that, in addition to focal fiontal lobe damage, disruption of connections of the fkontd lobe may be relevant in producing the deficit. The frontal systems, which include the fiontal lobe and its connections, have been suggested as the anatornic basis of fiontal lobe functions rather than the frontal lobe alone (Stuss, et al., 1997). fn previous research, where the damage was in the more posterior right fiontal regions, humor deficit may be due to a disruption of the underlying white matter and the connections of the fiontal lobe. A disruption of the underlying connections of the fiontal lobe might be important to a deficit in humor.

V. DISCUSSION

1. Introduction 2. Appreciation of verbal humor A. Mirth responding in nght fiontal patients (a)Decreased mirth responding in right frontal patients (b)Dissociation between cognitive and emotional reactions in right fi-ontal patients B. Quantitative performance on verbal humor appreciation tests 3. Appreciation of cartoon humor 4. Performance of bifiontal patients: Utilization behavior 5. Appreciation of nonverbal hurnor 6. Sense of humor 7. Hwnor production 8. Aging and humor 9. Theory of hurnor and the fiontal lobe

1. Introduction Hurnor provides an important avenue to examine cognitive and affective deficits, as well as changes in language, personality, and emotional functioning that occur as a result of brain damage. The aim of the present study was to examine whether damage to particular brain regions rnight produce an impairment in the processing of hurnor. In particular, it was hypothesized that the right fkontal region may be important to humor. In addition, the cognitive processes required for humor appreciation were also investigated in relation to the locus of brain damage. This was achieved by testing patients who were carefully selected with regard to the location of their brain darnage. Patients were first grouped by a standard matornical classification method. Five patient groups included in the study were those who had sustauied left fiontal, right fkontal, bifrontal, left postenor, or right posterior brain damage. The performance of these patient groups on a variety of tests designed to assess appreciation and production of humor, as weil as certain cognitive processes hypothesized to be related to humor appreciation, were compared to that of normal control participants. The patients with fiontai lobe lesions were then grouped according to their performance to examine further brain-behavior relations. The results of the study indicated that (1) Humor is a cornplex, multifaceted fûnction involving the operation of many cognitive processes. (2) An impairment in the appreciation and production of humor is related to damage to particular brain regions. That is, humor impairment is not caused by brain damage irrespective of locus. (3) Pathology involving certain regions in the right frontal lobe produce deficits in humor appreciation and production. (4) Humor appreciation is associated with specific cognitive processes, such as working mernory, cognitive shifting, abstract reasoning, and visual scanning and focused visual attention, which are also related to the fiontai lobe. The discussion will highlight the followhg: (1) Patients with right hemisphere lesions are impaired in the appreciation of verbal humor. This is based on qualitative observations (i-e., nght fiontal patients display inadequate mirth responses to hurnorous stimuli and their verbal responses are dissociated from their affectiveknirth responses) as well as quantitative performance on verbal humor tests. (2) Appreciation of verbal hurnor is related to cognitive processes of working memory, mental shifting, and abstract reasoning, indicating that these cognitive mechanisms are important to humor appreciation. (3) The performance of patients with bifrontal lesions may be characterized in terms of utilization behavior. (4) Nonverbal or cartoon hurnor is related to cognitive processes of working memory, visual search and scanning, mental flexibility, and visual directed attention. (5) Patients with right fiontal lesions rate themselves as having a lower sense of humor indicating that they may be aware of their impaired performance on the humor tests and may be monitoring their responses to hurnorous stimuli. (6) Right hemisphere pathology also produces an impairment in humor production. (7) Finally, a theory of humor and the fiontal lobe is presented, which argues for an integration deficit in patients with fiontal lobe pathology, particularly involving the integration of cognitive and affective information. This theory draws fiom the fünctional and anatornical evidence regarding the frontal lobe and outlines the importance of integration of cognitive and affective information to the highest of fiontal lobe functions, such as self-awareness and humor.

2. Appreciation of Verbal Humor The Funniness Rating Scale was used to assess hurnor comprehension and appreciation using only verbal stimuli. The verbal items used in this task were statements which made use of a play on words to convey their humor. This was a difficult task in that the verbal items were abstract, requiring the participants to go beyond the literal meaning conveyed by the statements. The verbal nature of the task provided a means of exarnining hemisphenc differences in the comprehension and appreciation of verbal humor. Since the stimuli were verbal, patients with left hemisphere damage might be expected to have greater difficulty on this task. The Joke Cornpietion Test was also a verbal task which assessed humor comprehension by requiring participants to complete joke stems by picking the punch line fiom arnong four alternatives. Along with the Story Completion test, this task provided additional information regarding the cognitive processes, as well as, the role of narrative language in humor comprehension. The Cartoon Rating Task examined humor appreciation by using verbal captions along with cartoon drawings, that is, both verbal and nonverbal information were important. The significant fïnding fkom these three taçks was that the appreciation of verbal humor was related to a specific brain region. While patients with lesions in the fkontal lobe as a group were significantly more impaired on humor tests compared to those with nonfiontal pathology, the right fiontal lobe was the critical brain region involved in the appreciation of hurnor, even though the humorous stimuli were verbal in nature. This conclusion was based on two observations: (A) The physical reactions or mirth responses of patients with right frontal lesions to humorous stimuli, and (B) The quantitative performance of the patients with right fkontal and bifiontal damage on the tasks assessing humor appreciation.

A. Mirth Responding in Right Frontal Patients A striking observation in patients with damage to the right fi-ontal region was their emotional reactions to the humorous stimuli. Two features of this abnomal ernotional reaction displayed by the right fiontal patients were: (a) The right fiontal patients demonstrated extremely muted physicaI or mirth reactions during the testing; and @) There was a dissociation between the cognitive/verbal reactions to humorous stimuli and the emotional reactions in patients with nght fiontal pathology. la) Decreased Mirth Response in Ri& Frontal Patients The Bght fiontal patients exhibited virtually no smiles or laughs during the administration of al1 humor comprehension tasks, unlike the normal control participants and patients with lesions in the lefl fiontal and postenor brain regions. This abnormal, rnuted reaction to hurnorous stimuli was unique to patients with right fiontal pathology. Such an almost total absence of physical reaction cannot be attributed to nght hemisphere darnage irrespective of location because it was not observed in patients with nght posterior damage. It was also not a feature of al1 fiontal groups, since those with left fiontal lesions were similar in their reactions to control participants. The bifiontal group was the only patient group which also exhibited a lack of physical reaction, though only on one task the Joke Completion task. This might be a consequence of their right fkontal pathology. The lack of mirth responses or the vimial absence of emotional facial expression in right fiontal patients in response to humorous stimuli has important implications. As Borod and Koff (1984) indicated, the face is a primary organ for communication and emotional expression. Of al1 animals, the human being has the most extensively developed facial musculature and depends heavily on facial behavior as a facilitator of social interaction. Kolb and Whishaw (1990) indicated that facial expression is one of the most salient cues to ernotion in humans. A deficit in facial expression of emotion in patients with right frontal darnage in response to humorous stimuli observed in the present study is therefore likely to have severe negative consequences in everyday social interactions for these patients. This is borne out in the literature where disorders of personality and affect are often in the foreground in accounts of patients with fkontal lobe Iesions (described in the literature review). Facial expression of emotion has received scientific attention. This literature is reviewed below and will indicate the following: (1) Studies investigating facial expression of emotion in normal subjects and unilateral brain damaged patients implicate the right hemisphere. (2) Ln terms of the specific brain areas involved, there is evidence that the fiontal areas are important in mediating facial expression. Further localization within the frontal lobes has been unclear. (3) Some research is available which raises the interesting possibility that the right frontal region may be çpecialized for spontaneous emotiond facial expression, whereas the left fkontal region may be Uivolved in mediating voluntary or deliberately posed facial expression. (4) Spontaneous emotional facial expression in response to hurnorous stimuli has not been investigated, although available literature points to the right fiontal area as being important. Wht Hemisphere and Facial Expression There is a substantial amount of research evidence with both normal and brain damaged subjects to indicate that the right hemisphere plays a dominant role in mediating emotional facial expression. Studies of 'facedness' or facial symmetry, Le., the relative intensity of ernotional expression on the two sides of the face, have been conducted to investigate hemisphenc differences in mediating facial expressions. As reviewed below, for normal subjects, the majonty of studies have suggested that the right hemisphere is dominant for posed and spontaneous expressions of facial emotion @orod, 1992). When normal subjects are asked to voluntarily pose facial expressions, generally, the left side of the face is judged as being more intense, that is, emotions are expressed more intensely on the left side (Campbell, 1978; Sackeim et al. 1978; Sackeim & Gur, 1978; Borod & Caron, 1980; Borod, et al., 1988). Studies investigating spontaneous expressions of facial emotion are few. Moscovitch and Olds (1982) reported that spontaneous unilateral facial expressions occur more frequently on the Ieft tfian on the right side of the face. Borod, et al. (1983) found no differences in facial asyrnrnetry in posed versus spontaneous expressions of emotion and majonty of the expressions were judged to be significantly left-sided. Dopson et al. (1984) also investigated posed as well as spontaneous expression of emotions and found similar results, Le., ratings of emotional intensity were higher for the left side of the face for both types of facial expressions. Further, the lefi sided intensity effect was stronger for spontaneous than posed emotions. The 'valence hypothesis', which maintains that negative emotions are primarily associated with the right hemisphere while positive emotions are associated with the lefi hemisphere, has also been investigated in studies of facial asymmetry of emotional expression. If this hypothesis is correct, negative emotions should be expressed more strongly on the lefi hemiface and positive emotion more strongly on the right herniface. Borod et al. (1983), analyzing posed and spontaneous facial expressions, found the left hemiface to be significantly more involved in facial expression than the right herniface. When expressions were analyzed according to valence, negative emotions were significantly left-sided, while positive emotions were not systematically lateralized. However, later studies have not supported a valence hypothesis. Borod et al. (1988) and Dopson et al. (1984) examined posed versus spontaneous facial expressions for both positive and negative emotions. A greater left-sided intensity was fomd for both types of emotions, failuig to support the notion of differential lateralization of positive and negative emotions. These studies, therefore, did not support the valence hypothesis of hemispheric specializahon. Overall, studies with normal subjects indicate that emotions are expressed with greater intensity on the left side of the face. This appears to be the case for both posed and spontaneous expressions, as well as, for both positive and negative emotions. Since the lower portion of the face is predominantly imervated by the contralateral cerebral hemisphere (Borod & Koff, 1990; Moscovitch and Olds, 1982), the finding of greater left herniface activity has been interpreted as reflecting right hemisphere dominance for facial expressions. Facial expressions of emotion have also been investigated in patients with unilateral brain damage. As with nomals, the right hernisphere is implicated as being dominant for facial expression of emotion. Buck and Dufw (1980) analyzed the spontaneous facial and upper body gestures in nght brain damaged, left brain darnaged, controls, and patients with Parkinson's disease, in a slide-viewing paradigm. Participants' facial expressions were videotaped covertly while watching slides that depicted either familiar people, scenery, unusual scenes, or unpleasant situations. The videotapes of the facial expressions of the participants ('senders') were then viewed by judges who guessed the type of slide shown on each trial, to calculate their 'sending accuracy'. Results indicated that the left brain damaged aphasic patients were equal to or more expressive than controls, indicating that patients more severely affected in symbolic communication (more severe aphasics) may actually be more facially and gesturally expressive. In contrast, nght brain darnaged and Parkinson' s disease patients were significantly less expressive. The authors suggested that spontaneous nonverbal expressiveness is rnediated by the right hemisphere, with the left hemisphere playing an inhibitory role. That is, expressiveness arising spontaneously fkom the present affective state of the patient is not disrupted and may even be facilitated by left brain damage (which mediates 'social display behaviors'), but is disrupted by nght brain damage. Borod and colleagues conducted a senes of studies of facial expressions of emotion in unilateral brain damaged groups. Compared to patients with left hernisphere damage or normal controls, those with right hemisphere pathology were more impaired, Le., less accurate or used facial channels of communication with less fiequency, in both posed (Borod, et al., 1986; 1988; 1990) and spontaneous (Borod, et al., 1985; 1986; 1988) facial expressions of emotion. Aspects of emotional facial expression (responsivity, appropriateness, intensity) were uncorrelated with non-emotional facial movement variables (paralysis, mobility, praxis) suggesting a dissociation between the systems controlling these two types of facial behavior (Borod, et al., 1988). Among patients with right hemisphere pathology, those with lesions involving the frontal or anterior regions were more impaired than patients with posterior lesions (Borod, et al., 1985; 1986). Borod (1992) sumrnarized available evidence on facial expression of emotion as follows. For normal subjects, the majority of studies have suggested that the right hemisphere is dominant for posed and spontaneous expression of facial exnotion. For brain damaged patients, there are differences related to elicitation condition, valence, and lesion site. For spontaneous expression, the rnajority of studies have reported deficits for right hemisphere patients, regardless of valence. Antenor lesions produce more impairment than posterior ones. For posed expression, right and left brain darnaged groups do not differ for negative emotions, but findings have been less consistent for positive emotions. Although this research suggests a special role for the right hernisphere in emotional expression, additional studies with more subjects, more discrete lesions, and a wider repertoire of positive emotions are needed.

Frontal Lobe and Facial Expression There is evidence that the frontal lobes are important in the emission of facial expression. A comrnon clinical observation in patients with frontal lobe lesions is a flattening of affect or shallow affect that may include a marked absence of facial expression (Stuss et al., 1992; Stuss and Benson, 1983; Kolb and Miher, 198 1a). Goldstein (1944) characterized frontal lobe patients as having rigid faces and a lack of expressive movements. Myers (1972) and Franzen and Myers (1973) reported that bilateral prefiontal ablations in rhesus monkeys produced a clear-cut decrease in spontaneous facial expressions. The prefrontally operated animals exhibited profound long-term changes in their affective responses. The fkequency and variability of their facial expressions, vocalizations, and social communicative geshues were greatly decreased. Typically, these animals exhibited a "poker- face" during any and al1 encounters. Thus, the prefkontal (and antenor temporal polar) regions were shown to be important in initiating or regulating facial expressions. Sirnilar deficits in facial expression have been reported in humans with fiontal lobe pathology. Hopf et al. (1992) reported cases of emotional facial paresis which refers to weakness of emotionally evoked facial rnovements such as smiling, as weIl as, patients with volitional facial paresis, which affects facial movements with voluntary effort, sparing activation on emotion. Patients with emotional facial paresis demonstrated symmetric activation of facial muscles dunng voluntary activation, but impaired activation with emotion, i.e., while srniiing or laughing. The lesion locations in patients with emotional facial paresis were varied and involved the frontal lobe white matter in some, as well as, the striatocapsular temtory, the anterolateral thalamus, insula, and other regions. The authors suggested that emotional facial paresis may be due to intemption of the connections between the thalamus and the frontal or mesial temporal lobes. In contrast, volitional facial paresis was reported to be caused by lesions of the motor cortex or the descending pyramidal tract. Gelmers (1983) reported a patient with a lesion in the right medial fiontal cortex who displayed unilateral ernotional facial paresis of the contralateral side. He had a rniId lefi-sided lower facial weakness at rest and on volition, with a striking weakness afier laughing. Kolb and Whishaw (1990) indicate that overall, studies of neurological patients have found a reduction in the frequency and intensity of facial expressions relative to more posterior lesions. Further, they suggest that large nght hemisphere lesions may have greater effects on facial expression than similarly sized left hemisphere lesions, although this does not appear to be mie in patients with restricted fiontai or temporal lobectomies. This was based on a series of studies by Kolb and colleagues. Kolb and Milner (198 la) studied spontaneous facial expressions which were observed under two conditions: (1)Patients with unilateral cortical excisions (left fiontal, right fiontal, centroparietal, and lefi temporal) were observed during postoperative neuropsychological testing, and (2)Patients undergoing intracarotid injection of sodium arnytal. The main finding was that the patients with frontal lobe lesions emitted significantly fewer facial movements. Patients with left fkontal lobe lesions produced significantly fewer spontaneous facial expressions (brow movements, srniles, and mouth and face movements) than the other patient groups with the exception of the nght frontal group. The nght fiontal group produced significantly fewer expressions than the left temporal and nght and left centroparietal groups. For sodium arnytal testing, observations of pre-injection behavior showed that when patients were classified accordhg to their eventual cerebral excision, those patients with frontal lobe lesions appeared to exhibit fewer facial movements than other patient groups. Neither changes in facial expression nor ratings of mood change were differentially affected by left and right carotid injections. The authors suggest that any changes observed der intracarotid injections, being of necessity, acute and transient, may differ frorn those following vascular lesions. Kotb and Milner (1981a) fürther reported that, although fkontal lobe lesions reduced the frequency of spontaneous facial expression, they had no effect on their diversity. That 1s. it was the spontaneity of the expression that was reduced, not the ability to produce thern. They indicated that reduced behavioral spontaneity appeared to be a frequent effect of frontal lobe lesions and suggested a parallel between decreased spontaneous facial expression and impoverishment of spontaneous narrative speech in left fiontal patients and reduction in the number of spontaneous meaningless drawings in patients with right frontal lesions. In another study, Kolb and Milner (1981b) found that lesions of either frontal lobe, but not central, parietal, or temporal lobe excisions produced impairments in the copying of a senes of three facial movements. However, no impairments were observed in the repetition of single facial movements. Kolb and Taylor (1988) examined the relative roles of the left and right fiontai and temporal lobes in the production and perception of facial expression. Subjects were asked to produce an expression appropriate for a faceIess character in real life cartoon drawings, and to mimic the emotional expression portrayed in a series of photos. Subsequently subjects chose the "best match" expression for the faceless character fkom a series of 6 key photos of people depicting different basic expressions, and also matched the series of photos with the six keys. The left frontal lobe group produced significantly less intense expression on both production tests than any other group. Right temporal subjects performed poorly on both perception tests whereas the left temporal subjects were normal on the face-rnatching task. Frontal lobe patients were also impaired at both tests. Therefore, they concluded that (1)lefi frontal lobe lesions impair both the production and perception of facial expression, (2)right temporal and nght fiontal lesions impair the perception of facial expression, and (3)left temporal lesions only affect the perception of emotional expression in context. Taken together, there is sufficient evidence to suggest that the fiontal lobe plays a special role in the contrd of facial expressions. However, both the left and the right fiontal lobes were implicated by Kolb and colleagues, whereas Borod and colleagues specifically implicated the right frontal region.

Right versus Lefi Frontal Lobe: Hemispheric mecialization for suontaneous emotional versus posed facial expression? In the present study, only the patients with nght frontal pathology exhibited a significant decrease in mirth responses, whereas those with left fkontal pathology responded similarly to the control group. This deficit in facial expression of emotion was observed during spontaneous elicitation of emotions, Le., in response to stimuli designed 10 elicit hurnorous responses. The results of the present study suggest that the right frontal region plays a dominant role in facial expression of emotion, and in particular, in spontaneous ernotional expression cornpared to the left fiontal region. In contrast, the left frontal region may be involved in mediating voluntq or deliberately posed facial expressions (although this was not exarnined in the present study). The reasoning behind this suggestion is outlined next. Buck and Dufe (1980) made a distinction between spontaneous facial expressions and gestures of emotion versus intentionally posed expressions and gestures. They suggested that this distinction rnay parallel that made in the literature on verbal behavior between 'propositioning', the use of words for the deliberate communication of a message, and 'ernotional utterance' which involves the use of words (e-g., expletives) in the expression of a presently existing emotion state. In aphasic patients, emotional utterance may be relatively intact while propositional speech shows deficits. Similarly, spontaneous facial expressions and gestures of emotion relating to a present ernotion state may be analogous to emotional utterance, while similar but intentionally posed expressions and geshires in the absence of an affective state may be analogous to propositioning. Such a distinction was supported by their results (described earlier) which showed that messages such as facial expressions that arose spontaneously fiom the affective state of the patient were not disrupted and may even be facilitated by lef? brain damage, but was apparently disrupted by right brain darnage. In other words, Buck and Du£@ (1980) suggested that in the spontaneous communication of emotion, the communicative behavior, whether it be a clenched fist, a body movement or posture, a facial expression, or an affectively-toned verbal response, arises not fiom an intention to communicate but directly in a natural or conditioned relationship with an emotion state occegwithùi the individual. They Mersuggested that intention to communicate was the common feature in the distinctions between propositional versus emotional utterance, and communication via symbols versus signs. The crucial feahire in spontaneous communication is that the communicative behaviors are directly related to a present emotion stare and this is mediated by the right hemisphere. In the absence of such a state, communication rnust be symbolic, propositional, or intentional and hence mediated by the left hemisphere. In the present study, the absence of smiles or laughs in response to hurnorous stimuli in the right fiontal patients reflects a deficit in facial expressions that arose spontaneously and was directly related to the curent affective state of the patient. Myers (1972) also supports a distinction between spontaneous versus volitional control of facial expression. His research hndings shovved that bilaterd prefiontai ablations in rhesus monkeys produced major losses in facial expressions and in vocalizations. He also suggested that these functions participate prirnady in emotional social communication. For instance, he reported a major difficulty in bringing rhesus rnonkey vocalizations under instrumental or conditioned control. That is, in this species, there is a great difficulty of access between the volitional control mechanisms of the cortex and the vocalization apparatus. Therefore, the facial expressions and vocalizations in rhesus monkeys were suggested to participate primarily in emotional and social communication. That is, the utilization of the face and voice in the monkey is believed to be largely under affective control and to be ahost entirely involuntary. The monkey facial expressions and vocalizations were seen as being predominantly given over to the expression of inner states of being and to play primdy social signaling roles. It was suggested that such a more complex use of the face and voice in social communication develops for the first tirne at the rnonkey Ievel of primate evolution. At the time of its early evolution, complex face and voice use is restricted largely to expressions of affect. However, with Merprimate evolution through higher apes and man, a second separate and distinct control over the facial and vocal apparatus evolves yielding finally in man the added capability of voluntary control over the face and voice for the more detailed expression of the content of our consciousness and of the rneaning of our past and present experience. Myers (1972), therefore, supports the hypothesis of a dual control of the face and voice in man whereby there still exists prominently the emotional or affective element which mediates dl involuntq or spontaneous emotive expressions of feeling. This more primitive and aged mechanisrn for face and voice control is believed to utilize quite different neural control mechanisms than does the more recently derived systcm which provides for a volitional face and voice control. This more recent system has developed embedded within the posteriorly located analytic and mnemonic cortical tissues and provides for communication between individuals within the species at symbolic, verbal levels. Though Myer's results indicated that the frontal lobes were involved in the control of primate facial expression, it did not provide any information regarding laterality because the prefirontal ablations were bilateral. Since he theorized that the monkey facial expressions participate primarily in emotional communication, it would be interesting to examine whether a nght frontal lesion would be sufficient to produce a deficit in their facial expressions. Based on the dual control for facial expressions suggested by Myers (1 972), as well as, Buck and Due's (1980) distinction regarding spontaneous versus intentionally posed emotion and gestures and their evidence that right hernisphere pathology affected the ability to communicate spontaneous facial expressions and gestures relating to a present emotion state, we may question whether such a distinction may extend to the left versus right fiontal region in mediating facial expressiveness. That is, this duality may manifest itself as a predorninantly left fiontal control over posed / volitional facial expressions versus a right frontal control over spontaneous emotionai facial expressions. The absence of emotional facial expression in right frontal patients is in accord with the dominant role attributed to the right hernisphere in affective cornponents of language, which include spontaneous affective prosody and emotional gestunng (Ross, 198 1; 1993). The drastic reduction in spontaneous smiling and laugbg observed in the present study in right fiontal patients in response to humorous stimuli when compared with the control group, might be part of a deficit in spontaneous affective gesturing reported in right brain damaged patients. Ross (1993) remarked that gestural kinesics (the study of limb, body, and facial movements associated with language and communication) has not been well studied neurologically. Ross and Mesulam (1979) and Ross (1981; 1993) pioneered investigations into the possible relationship of nght brain damage and loss of affective prosody and emotional geshiring. Ross and Mesulam (1979) observed that lesions of the right fiontal operculurn may cause complete loss of spontaneous gestural activity in the nonparalyzed face and limbs. Ross (1 98 1) proposed that the affective components of language encompassing prosody and emotional gesturing were a dominant function of the nght hemisphere in keeping with its putative roie in the modulation of dfective behavior. Further, he suggested that the functional- anatomic organization of prosody and emotional geshiring in the nght hemisphere mirrors that of propositional language in the left hemisphere. For instance, he reported cases of patients with lesions involving the right frontal regions who displayed motor aprosodia. The features included flat and monotonous speech with little spontaneous prosody and greatly reduced or absent spontaneous gesturing, giving them a flat affect. Thus, Ross (1981) claimed that disorders of emotional communication are the primary deficits resulting fkom right hemisphere damage. Borod et al. (1983) indicated that emotional expression cm be thought of as distributed along a posedkpontaneous continuum and it is not clear whether fïndings for posed facial expression of emotion can be generalized to spontaneous facial expression. Most of the researchers in this area have raised this issue of a differentiation between the two types of emotional expression (e-g., Borod, Koff? and White, 1983; Borod et al., 1986; 1988; Dopson et al. 1984). The studies on facial expression of emotion reviewed earlier have provided some conflicting evidence with regard to the hemispheric specialization of posed versus spontaneous emotional expressions. As Borod (1992) surnmarized, for normal subjects, the majority of studies have suggested that the right hemisphere is dominant for posed and spontaneous expression of facial emotion. However, for brain damaged patients, for spontaneous expression, the rnajority of studies have reported deficits for nght brain damaged patients, in particular, those with fiontal or anterior lesions, regardless of valence. For posed expression, right and left hernisphere patients are reported not to differ for negative emotions, but hdings have been less consistent for positive emotions. A number of rneîhodological differences among the studies, such as the tasks used to elicit emotional expressions, the discreteness of lesion, and the method employed to assess asyrnmetry of facial expression, could give nse to the inconsistency in the results. Nevertheless, there appears to be a consensus regarding the deficit in spontaneous emotional expression in nght hemisphere patients, with a particular emphasis on right fiontal lesions. Any conclusions regarding the role of the left fiontal regions in posed or voluntary facial expressions awaits more research. The senes of studies by Kolb and colleagues which implicate the left fiontal region in the

9 expression of emotion mostly examined deliberateiy posed facial expressions. In the Kolb and Miher (1 98 1b) and Kolb and Taylor (1988) studies, patients were asked to copy or deliberately rnimic emotional expressions. In both these studies, patients with lefl fiontal lesions were impaired, lending support to the notion that the left frontal regions may be involved in voluntary expressions of facial emotion. However, the Kolb and Milner (1981a) study implicated both the left, as wel1 as the right, fiontal regions in spontaneous facial expression of emotion. The spontaneous facial expressions in their study were observed during neuropsychological testing (during the administration of the McGill Picture Anomaly Series and the kst 10 minutes of the Wisconsin Card Sorting Test (WCST), as well as during sodium amytal injection. However, these situations intuitively do not appear to be conducive to the expression of spontaneous facial expression, since these were mostly neutrd stimuli and not necessarily stimuli designed to arouse strong emotions. As Borod et al. (1986) also pointed out, it is not clear what percent of these facial expressions were emotional. (It might have been interesting to see whether facial expressions differ during later stages of the WCST as frontal patients might become increasingly hstrated). In contrast, Buck and Duf@'s (1980) study, which used stimuli chosen specifically for their ability to arouse emotions irnplicated only the right hemisphere in spontaneous emotional expressiveness. Neuroanatomical evidence also supports a differentiation between the systerns controlling spontaneous versus voluntary facial expressions, each mediated by different brain regions. Studies of patients with certain neurological disorders suppoas such a distinction (e.g., Kahn, 1966; Tschiassny, 1953). Lesions in the py~ddaisystem impair the ability to perform facial movement on request such as the ability to smile when asked to do so, yet may leave emotionaI expression intact so that the patient might srnile if amused by a joke. Lesions in the extrapyramidal systems are implicated in the opposite pattern so that a patient could srnile on request but spontaneous or emotional reactions are impaired (Borod et al., 1983; Moscovitch and Olds, 1982). Hopf et al. (1992) also differentiated between volitional facial paresis caused by lesions of the motor cortex or the descending pyramidal tract and emotional facial paresis in which the fiontal areas were part of the damaged system. However, they did not speciQ the methods used to study emotional facial expressions in their patients, Le., the stimuli employed to evoke emotional facial activation were not reported. In patients with emotional facial paresis consequent to fiontal lobe pathdogy, on imaging, one had a left frontal tumor with severe edema of the entire fiontal white matter, while two had right fiontal involvement. Similarly, Gelmers (1983) reported emotional facial paresis associated with a lesion in the right medial fkontal cortex. Thus, it seems probable that the nght fkontal regions may be more involved in emotional facial paresis. It would be interesting to examine whether volitional facial paresis occurs more with left fkontal lesions.

Right Frontal Lobe: Role in spontaneous emotional facial expression to humorous stirndi. Humor provides a means of examining emotional communication. However. facial expressions of mirth arising spontaneously in response to humorous stimuli has not been investigated systematically in neurological patients. In the present study, facial expressions of mirth observed in focal brain damaged patients were recorded in response to humorous stimuli, i-e., stimuli which can be seen to naturally arouse emotion (amusement) and therefore, spontaneous facial expressions that are related to the emotion state presently being experienced (Le., smiles and laughs). Based on Buck and DufW7s (1980) distinction, it is logical to expect that right hemisphere patients will show a deficit, and given the involvement of the £?ontal regions in facial expression, right fiontal patients would be more impaired in ternis of reduced spontaneity of rnirth expression. The present study found this pattern of results, Le., right fiontal patients demonstrated significantly reduced or absent mirth responding, whereas lefi frontal and nonfiontal patients did not differ in rnirth responding compared to control participants. Only one other study is available which examined mirth reactions specifically aroused by hurnorous stimuli. Ln this study, Gardner et al. (1975) reported similar results where RHDs generally had a muted emotional reaction to hurnorous displays giving virtually no mirth responses, with only a few exceptions. In contrast, the left hemisphere aphasic patients behaved in a way similar to the normal patients. In particular, the left anterior patients designated the relevant depicted elements, said or pointed to relevant words, and tended to smile or laugh appropnately when they understood a cartoon. The right hemisphere patients, however, tended to exhibit one of two extreme reactions: either they laughed at nearly every item, even when understanding was doubtfbl, or, more comrnonly, they cvinced little reaction to any item, even when their understanding seemed adequate. The body of research currently available on facial expression of emotions, definitely points to a nght hemisphere dominance in mediating spontaneous emotional expressions. This dominance can be merlocalized to the right fiontal region. Although the results of the studies by Kolb and colleagues indicate that the left fiontal region is involved in the production of voluntary facial expressions, research in this area is still at a preliminary stage. Gainotti et al. (1993) reviewed the literature dealinp with the neuropsychological study of human emotions. They concluded that the results of the investigations conducted with normal subjects and brain damaged patients suggest that the right and left hemispheres might play a complementary role in emotional behavior. The right hemisphere seems to be involved preferentially in functions of emotional arousal, intimately linked to the generation of the autonornic components of the emotional response, whereas the lefi hemisphere seems to play a more important role in functions of intentional control of the emotional expressive apparatus. At the level of the fiontal lobes, they indicate a magnification of the specific role played by the right and lefi hemispheres in the processing and regulation of emotions, with a greater involvement of the nght frontal lobe in spontaneous emotional responding and a prevalent role of the left frontal cortex in the modulation and control of immediate emotional reactions. The results of the present study add support to evidence fiom previous research in indicating that the right ftontal region appears to be dominant for spontaneous or ernotional facial expressions. This right fiontal specificity in tems of response to humorous stimuli has not been reported before. However, more research is needed to substantiate the hypothesis that the left frontal region may be more involved in the control of voluntary or posed facial expressions. This might prove to be an interesting and hitful avenue of research, providing greater knowledge regarding the lateralization of emotional function within the fkontal lobes. The results of this study indicate that the nght fiontal region is cntical for mediating facial expressions and gestures in response to emotional stimuli such as humor.

Cb) Dissociation Between Coenitive and Emotional Reactions in Rkht Frontal Patients The second feature observed in patients with right frontal damage in this study was a dissociation between cognitive and emotional reactions during the administration of the humor tests. That is, there were instances where humorous stimuli were quantitatively rated by the right fiontal patients as being quite funny, very -y, or extrernely funny (funniness ratings of 3,4, or 5), and understanding of these items appeared to be adequate (based on their explanations as to why they rated these items as being Ginny). However, even in these instances, unlike the control participants and other patient groups, the right fiontal patients did not respond to these items with smiles or laughs. These observations indicate that the emotional or affective reactions of patients with right fiontal lesions can become dissociated from their cognitive evaluations. (mese were not statistically analyzed because of the small number of observations). A similar dissociation was reported by Gardner et al. (1975). Ln their study, in nght hemisphere patients, whether a patient laughed bore little relation to his comprehension of the cartoon. Right hemisphere patients tended to exhibit one of two extrerne reactions: either they laughed at nearly every item, even when understanding was doubtfûl, or, more commonly, they evinced Iittle reaction, even when their understanding seemed adequate. In contrast, the left hemisphere aphasic patients behaved in a way similar to the normal patients. In particular, the left anterior patients designated the relevant depicted elements, said or pointed to relevant words. and tended to srnile or laugh appropriately when they understood a cartoon. In other words, in the lefi hernisphere patients, the emotional reactions matched the cognitive reactions. However, in the Gardner et al. (1975) study, the mirth responses in right hemisphere patients were not analyzed in terms of lesion location within the hemisphere. Therefore, it is not known whether decreased emotional reactions, as well as, a dissociation between cognitive and affective responses among right hemisphere patients was a particular feature of those with right frontal pathology as in the present study. Stuss and Benson (1983) provide support for a dissociation between language and action in emotional responding in frontal lobe patients, i.e., between aspects of emotional functioning- They conducted an investigation of emotion in patients who had undergone prekontal Ieukotomy. Three tests, the Thematic Apperception Test, matching of facial expressions, and an Emotional Situations Test were adrninistered. They report that outward emotional reaction (affect) proved difficult to assess in these patients and that the patients were poor at verbalizing their emotional state and, even more pertinent, showed almost no reiationship between the verbal response and the outward manifestation as observed by the examiner, indicating a divorce of language and action. Further, they reported that on the Emotional Situations Test, the leukotornized subjects often failed to associate their perceptions with a situation. The authors suggested that this dissociation of perceptual and cognitive awareness could be considered a cognitive defect of emotion. One aspect of the reported personality disturbance following frontal lobe damage appears to be an inability to translate mood or emotion into appropnate behavior. The personality thus appears to be a disconnected phenornenon with the emotional behavior separated from the environment. That is, in the prefrontal leukotornized patients there was a separation of the verbal and physical responses of emotional behavior. The dissociation between the right fiontal patients' verbalizations and cognitive evaluations (Le., ratings of funniness and explanations of humor) and the observed physical response (lack of appropriate smiles or laughter) in the present study, is similar to the dissociation between cognitive and physical reactions reported in prefiontai leukotomized patients (Stuss and Benson, 1983) and in right hemisphere damaged patients (Gardner et al., 1975). Gardner et al. (1975) analyzed RHD as a group. In the present study, RHD patients with nonfiontal lesions (right postenor group) were NOT different fiom the control group. This suggests that a blunted emotional-physical response and a dissociation between cognitive and physical aspects of emotional behavior in terms of responding to humorous stimuli reported in RHD patients is more specifically ahbutable to a ïight fiontal deficit. The inappropriate response of right fiontal patients to humorous stimuli observed in the present study fits well into the profile of emotional and personality changes described in the literature as the most striking consequence of right fiontal darnage (reviewed in Stuss et al., 1992). A prominent feature of this personality and emotional disturbance is a disorder of humor. Abnomai behaviors, such as, moria (stupidity / silly, euphonc behavior) and witzelsucht (addiction to joking / tendency to tell inappropriate jokes) has been described in numerous reports of patients with fiontal lobe damage, particularly in association with right frontal lesions (reviewed in Benton, 1991 ). Vardi et al. (1994) described a patient with right fiontal dysfunction who demonstrated inappropriate laughter and perseverative joking. Also, the patient was nondiscrirninating toward his jokes or puns, their context, and their impression upon the audience. The patient himself never laughed at his jokes. In addition, he did not react to jokes told by others and was insensitive to their humor. This report indicates that joke telling or humor production could becorne dissociated from humor comprehension and appreciation as a result of right f?ontal pathology. In the present study, a dissociation between affective and cognitive reactions to humorous stimuli was observed. Therefore, in patients with right frontal damage, different aspects of humor functioning might become dissociated. To summarize, the qualitative reactions of patients with nght fiontal pathology were abnormal compared to other groups. They displayed virtually no physical reactions of mirth or facial expressions of emotion. Also, their affective responses were dissociated f?om their cognitive reactions and verbalizations. Previous studies have suggested a deficit in humor appreciation (Gardner et al., 1983) and rnirth responding (Gardner et al., 1975) in right hemisphere patients. In the present study these were unique to nght fiontal patients. They appear to be a consequence of nght fiontal damage specifically, since they were present only in right fkontal and bi£?ontal patients (who also have right frontal damage). It does not appear to be a feature of al1 right hernisphere patients in that the nght posterior patients did not differ from the control participants in their reactions to humorous stimuli. It is also not a feature of al1 frontal lobe patients, since the lefi fiontal patients did not differ from the control group. nius, right fkontal damage appears to be the cntical requirernent for a deficit in appropriate responding to humorous stimuli.

B. Quantitative Performance on Verbal Hurnor Appreciation Tasks Comprehension and appreciation of humor, like mirth responding or emotional-physical reactions, also appears to be related to specific brain regions. The results of the Funniness Rating Scale and the Joke Completion test revealed that right fiontal and bi£iontal patients were significantly duninished in their performance compared to the control group. Contrary to what might be expected on the grounds that the lefi hernisphere is generally dominant for language, comprehension and appreciation of verbal humor was impaired in patients with right fkontal and bifrontal lesions, while those with left hntal tesions demonstrated no impairment on these tasks cornpared to the control group. The results of the Funnùiess Rating Scale showed that right fiontal and bifiontal patients had difficulty in distinguishing between humorous and neutral stimuli. These results confum to some extent those reported by Gardner et al. (1983) who also found that normal controls made a "far clearer" distinction between the hinny and unfunny items than did RHDs. In their study, RHDs responded similarly to nomals on truly humorous items, but also treated the unfunny items as more humorous than did the controls. The results of the Funniness Rating Scale provide merspecificity over those reported by Gardner et al. (1983). That is, the present study demonstrated that an impairment in the ability to distinguish between humorous versus neutral stimuli was specific to those with right fiontal lesions only and not to al1 right hemisphere damaged patients, since those with right postenor lesions did not differ from conû-01 participants in distinguishing between the two types of stimuli. Patients with lefi fiontal lesions perfonned similarly to control participants on the Funniness Rating Scale, indicating that left frontal damage was not sufficient to produce an impairment on this task. A deficit in distinguishing fùnny fkom neutral items can be specifically attributed to right fkontal damage. Therefore, the impairment exhibited by the bifiontal group on this task can also be viewed as a consequence of damage to their right frontal region. This inability to distinguish behveen humorous versus neutral events in those with right frontal darnage is reflected in the accounts of personality and emotional change reported in these patients. Clinical evidence indicates that a significant feature of personality change in patients with right frontal damage is their production of hurnor at inappropnate times and places (reviewed by Benton, 199 1). Bogousslavs~et al. (1988) reported a patient with right frontal system damage given to making inappropnate cornrnents and jokes. Vardi et al. (1994) published a case report of a patient with hypoperfusion in the right frontoparietal areas on SPECT, whose disturbed behavior included inappropriate laughter and a ritual repertoire of puns and jokes, which were viewed by the patient as a normal style of speech. Also, "the patient remained nondiscriminating toward his jokes or puns, their context, and their impression upon the audience. The patient himself never laughed at his jokes. He did not react to jokes told by others and was insensitive to their humor". These behavioral disturbances reported in patients with right fiontal damage rnight have as their basis the inability to distinguish between humorous versus neutral events. This rnight underlie their difficulty in understanding humor produced by others, as well as, an inability to evaluate situations regarding their suitability for the expression of hurnor. The observation that right fiontal and bifrontal patients experienced difficulty in differentiating verbal humorous material frorn neutral statements on the Funniness Rating Scale suggests an impairment in the comprehension and appreciation of verbal humor in these two goups. This received Mersupport fiom the results of the Joke Completion Task. The Funniness Rating Scale only required participants to rate stimuli for their perceived funniness. Performance on this task did not provide direct evidence of whether the verbal stimuli were actually comprehended by the participants before assigning ratings to them. However, since the ratings açsigned to humorous items differed fiom those assigned to neutral items by most participants, it was an indication that the stirnuLi were comprehended before they were rated. In other words, the verbal statements need to be adequately understood in order that humorous items be rated as being funnier than the neutral items. Patients with teft frontal and lefi postenor lesions were able to distinguish adequately between hurnorous and neutral items in terms of the funniness ratings assigned to them, indicating that they did comprehend the stimuli. even though they were verbal. However, since patients with right fiontal and bifkontal lesions failed to differentiate adequately between these two types of stimuli, it might be questioned whether they did indeed comprehend the items (although theoretically, since the lei? hemisphere is generally considered to be dominant for language, right fiontal patients should not be affected by the verbal nature of the task). In other words, did these two groups fail on the task because they could not comprehend the verbal stimuli? The Joke and Story Completion Task was designed to answer this question of whether a deficit on verbal hurnor tasks was a consequence of a deficit in language comprehension, especially involving narrative language, by comparing performance on the Joke versus the Story condition. The Joke Completion Task required participants to cornplete joke stems by selecting fiom among four alternative endings, the original punchline, which was the only correct funny choice. Performance on the task required a sensitivity to the element of surprise in hurnor, as well as, the capacity to establish coherence between the punchline and the body of the joke (Brownell et al. 1984; Bihrle et al. 1986). According to this two-stage model of hurnor processing, the Incongruity-Resolution model, incongruities are recognized in the first stage, which are then resolved in the second stage. It is these two processes, inconpity recognition and inconpity resolution, which lead to humor comprehension, as well as successful performance on the Joke Cornpletion Task. Therefore, poor performance on this test would indicate an impairment in one or both of these processes, resulting in a deficit in hurnor cornprehension. The Joke Completion Task dso provided a means of analyzing the reason for failure on the task. This was accomplished by exarnining the types of alternative endings chosen to complete the joke stem, when an incorrect choice had been made. Three incorrect endings were provided in addition to the correct punchline. The incorrect endings were: 1. Humorous nonsequitur (HNS), which contained humorous but slapstick content; 2. Straightforward (SF) ending, which provided an ordinary, unsurpnsing conclusion; and 3. Associated nonsequitur (ANS), which was related to some element in the joke stem without providing a satismg conclusion that was consonant with the therne. Choice of HNS endings refiected a sensitivity to the element of surprise in hurnor, the recognition that a joke stem must end in surprise. This choice, however, would be incorrect because it does not establish coherence wvith the information presented in the body of the joke. Choice of the HNS ending which is surprising but incoherent, therefore, indicated intact functioning of the first element - sensitivity to surprise, necessary for hurnor cornprehension, but a deficit in the second stage, establishing coherence. In contrast, the choice of SF endings would lead to the opposite conclusion. SF endings, which were unsurpnsing and coherent, reflected a failure to appreciate the element of surprise or incongruity necessary for most successful humorous material. Choice of SF endings, therefore. reflect a deficit in the first stage of humor, an inability to appreciate the importance of surprise in humor, but intact functioning of the second stage, the ability to establish coherence between parts of a narrative. The results of the Joke Completion Task were similar to those of the Funniness Rating Scale. Patients with frontal lobe pathology made more errors compared to the control group. In particular, the right fkontal and bikontal patients had difficulty performing the task, obtaining significantly fewer number of correct items compared to the control group. The lefi frontal patients' performance did not diEer significantly fiom that of the control group. Therefore, only the right frontal and bifiontal groups exhibited an impairment in hurnor cornprehension on this task. Further information on this humor comprehension deficit exhibited by right frontal and bifrontal patients is provided by analyzing the pattern of their errors, that is, by an examination of the incorrect endings selected by these patients to complete the joke stems, in place of the original punchline. Right fkontal patients were found to demonstrate a preference for hurnorous nonsequiturs (Hl%). That is, right fiontal patients perfomed worse on the task because they chose slapstick WS) endings more fkequently than control participants to cornplete the joke stems. They did not choose the other two ending types (SF and ANS) significantly more often than control participants. The right fiontal patients were more than three times likely to choose HNS over SF and ANS endings. The pattern of their errors suggests that right eontal patients retained a sensitivity to the role of surprise, i-e., an understanding of the necessity for surprise in humor. They failed on the task because, once they had registered surprise, they did not progress to the next stage and attempt to estabIish coherence between the punchline and the body of the joke. The results of the Joke Completion Task in the present study are, in some ways, similar to those reported by Brownell et al. (1983) and Bihrle et al. (1986). The Joke Completion Task employed in the present study was the sarne task designed by these investigators (Bihrle et al. 1986). In the Brownell et al. (1983) shidy, RHD patients performed significantly worse than normal controls, demonstrating a significant attraction to nonsequiturs. In the Bihrle et al. (1986) study, RHD patients performed worse overall than LHD patients on the cartoon task. Also, RHD patients were most attracted to nonsequitur, particularly, HNS endings, and were least attracted to SF endings. In contrat, their LHD patients were least attracted to HNS but most attracted to SF endings. In their verbal analog task (Joke Completion Task), results closely paralleled those of their cartoon task, with the RHDs being rnost attracted to HNS endings. The present study extends and refines these findings. The right hemisphere is important, but a deficit was NOT observed in patients with lesions anywhere in the right hemisphere. The nght posterior patients tested in this study did not perform significantly worse than control participants. They also did not show a significantly greater preference for HNS endings compared to the control group. Therefore, the right frontal patients in the present shidy demonstrated the characteristic RH.profile reported by Brownell et al. (1983) and Bihrle et al. (1986), perfoxming significantly worse overall than normal controls, and being significantly more attracted to HNS endings, while the right postenor group did not. This indicates that this is a more focal deficit attributable to right fiontal damage, rather than to right hemisphere darnage in general. LHD patients were not adrninistered the verbal Joke Completion Task by Brownell et al. (1 983) and Bihrle et al. (1 986). In the present study, the overall performance of the left frontal patients did not differ significantly f?om that of the control group. They also did not show a significantly greater preference for HNS or SF endings compared to the control group. The left posterior patients also did not differ significantly fkom the control group in overall performance levels or choice of ending type. That is, despite the verbal nature of the task, the left hemisphere damaged patients in our study (who had been screened for their overall ability to understand) showed no impairment. The second group whose performance was significantly worse compared to the control group in the present study was the bifiontal group. The bifiontal patients had the worse performance overall. The pattern of their emors, however, differed from that of the nght fiontal group. The bifkontal goup, unlike the right frontal patients, who were attracted mainly to HNS endings, did not show a decided attraction to any one type of incorrect ending. The bifrontal patients chose al1 three error types, Le., HNS, SF, and ANS, significantly more often than did the control group. This is in contrat to the right frontal group, whose attraction to HNS endings reflected an irnpairment in only the second stage of humor processing. The pattern of errors exhibited by the bifiontal group, on the other hand, might be indicative of a more pervasive deficit in humor processing. The right fiontal and bifiontal groups' humor comprehension deficit on the two verbal tasks, the Funniness Rating Scale and the Joke Cornpletion Task, is contrary to naive expectations based on the theoxy of the left hemisphere7s dominant role in language. The inability to distinguish clearly between humorous and neutral verbal stimuli on the Funniness Rating Scale cannot be attributed to a mild language deficit, since left fiontal and left posterior patients did not differ significantly fiom controls in their performance. Similarly, on the Joke Completion Test. left frontal patients did not show the nght fiontal groups' pattern of errors. The left postenor group also did not demonstrate a significant deficit on this task compared to the control group. A number of recent investigations are available which confer the right hemisphere an important role in language, especially in the processing of comected discourse and in the understanding of noditeral language (e.g., Wapner, Hamby, & Gardner, 1981; Gardner et al., 1983; Foldi, 1987; reviewed earlier). Thus, the hurnor deficit has been seen as an instance of a right hemisphere deficit in discourse and narrative language (e-g., Wapner, Hamby, & Gardner, 198 1; Molloy et al., 1WO), a difficulty with the subtle and complex aspects of language, rather than a humor deficit per se. The Story Completion Task was designed to address the issue of a nght hemisphere deficit on narrative language tasks in relation to their impairment on the Joke Completion Task, a narrative foxm that requires surprise (Bihrle et al., 1986). The earlier investigation by Brownell et al. (1983) had indicated that RHD patients showed a preserved sensitivity to surprise but an impaired ability to establish CO herence (based on their pre ference for HNS endings) . However, as Bihrle et al. (1986) pointed out, the Joke Completion Task by itself did not adequately answer the claim that RHD patients had an intact appreciation of the surprise element in narratives. The Story Completion Task was therefore administered in conjunction with the Joke Completion Task. The Story Task, employed by Bihrle et al. (1986), also utilized the same type of foils as those used in the Joke Completion Task. It therefore allowed an examination of whether patients knew when surprise was appropriate and when it was not. in other words, if RHD patients were really sensitive to the surprise element of humor, they should be able to apply it appropriately in the case of jokes and refhin fkom applying it in the case of stories. Similady, if RHD patients had difficulty establishg coherence, this impairnent should affect performance in other narrative tasks, such as choosing a correct, coherent ending for nonhumorous items. such as stories. This was accomplished by Bihrle et al., (1986) by adrninistering the Story condition. In this condition, the same joke stems were presented as in the Joke condition. However, the original punchline (FC) was now omitted, but other ending types or foils (ENS, SF, and ANS) were retained. Participants were now asked to choose a logical conclusion to the story. The straightfonvard ending (SF) was now the correct choice. That is, by substituting a straightforward ending for the punchline, the shoa story jokes were transformed into nonhumorous vignettes. Bihrle et al. (1986) found that the performance of RHD patients on the story condition (45.7% errors) closely paralleled those obtained on the joke condition (46.5% errors). In the story condition, however, RHDs were most attracted to ANS endings. This Mersupported their view that the way in which RHD patients process jokes and stones was consonant with accounts of their performance on other narrative tasks. That is, as with other narrative tasks, RKD patients seemed to appreciate isolated meanings, but could not consider the importance of relevant information for revising their initial interpretation. The present study also clarified this finding. Right fiontal patients, though impaired on the Joke Completion Task (22.9% enors), were not significantly impaired compared to the control group on the Story Completion Task (6.25% errors) or the story condition. In the few instances where they erred in the story condition, they were more likely to choose ANS endings and refrained fkom selecting HNS or slapstick endings. This suggests that right fiontal patients did retain an appreciation of the forma1 differences between a joke and a neutral vignette. They realized that surprise was an important element in humor, while being inappropriate in the story and therefore, did not select HNS or slapstick endings to complete the stories. Their performance on the Story task, which was comparable to that of the control group, showed that the nght fkontal patients tested in this study were not deficient in narrative comprehension. They were able to establish coherence and make appropriate straightforward endings to complete the short stories in a logical manner. If their difficulty with the Joke task was a consequence of a deficit in narrative language, this deficit should have produced impaired performance on the Story task, which was also a narrative language task. This suggests that, their humor deficit on the Joke Completion task, rather than being a consequence of their narrative or discourse deficits, might be independent of their language functioning. That is, adequate linguistic function was not sufficient for comprehension of verbal humor. Instead, the humor comprehension deficits displayed by right frontal patients on the Joke Completion task may be reflective of a disturbance in other functions subserved by the fiontal lobe such as worbg memory, cognitive flexibility, and abstract ability. Bifiontal and right posterior groups were the only patients whose performance was significantly worse than that of the control group on the Story Completion Task. Though both these groups obtained significantly fewer items correct overall, they differed in terms of the incorrect ending type selected. Bifbntal patients chose significantly greater number of HNS, as well as, ANS ending types compared to control participants. The bifiontal group was the only group to choose significantly more HNS endings to complete items in the story condition. In contrast, the right posterior group, when they erred, chose only ANS endings and completeiy refrained from choosing HNS or slapstick endings. This pattern of errors suggests that the nght posterior patients appreciated the formal difference between a joke and a nonhumorous story. That is, although their poor performance on the Story task suggested an impairment in narrative language, they understood that a surprishg or slapstick ending would be inappropnate to complete a nonhumorous story. Also, their better performance on the Joke task in cornparison with the Story task suggests that, in spite of a narrative language deficit, they were still sensitive to verbal hurnor. Therefore, deficient performance on the verbal Joke Completion task might be a consequence of deficits in other functions rather than merely linguistic impairment. The results of the two verbal tasks, the Funniness Rating ScaIe and the Joke Completion task, indicating that the nght fiontal region is critical to hurnor comprehension and appreciation, is supported by literature regarding the role of the right frontal lobe in language, emotions, personality, and self-awareness (described in the literature review). With regard to language and communication, Alexander, Benson, & Shiss (1989) provide evidence indicating the involvement of the fiontal lobe in certain kinds of discourse or narrative functions, such as, maintaining connectedness and relevance in a narrative by the application of attention and self-cntical observation, generating and appreciating abskact I nonliteral language, and utilizing indirect forms of communication, e.g., sarcasm and irony. In particular, Sght frontai damage cm produce dismptions in affective or pragmatic intent, and attempts at humor and sarcasm appear inappropriate or awkward in these patients. Poor comprehension of cartoons, sarcasm, and indirect requests is reported in a patient with nght posterior &ontal lesions Thus, the role of the right fiontal lobe in language may be specific to figurative or nonliteral language, whose cornprehension requires abilities such as working mernory, shifiing and abstractiori, which are also fiontal fünctions (descnbed in earlier sections). Humor falls within this realm. Given the rote of the rîght fiontal region in nonliteral language, we would expect these patients to demonstrate impairments in verbal humor tasks such as the Funniness Rating Scale and the Joke Cornpletion task, while not affecting performance on the Story Completion task, which does not involve figurative language. This is supported by the results of the present study, where the right fiontal patients exhibited this pattern. Poor perfomance on the verbal humor comprehension tasks, the Funniness Rating Scale and the Joke completion task by only right fiontal and bifrontal patients indicates that rather than being a linguistic deficit per se, functions subserved by the fkontal lobe are important in humor comprehension. These fiontal bctions, working memory, mental flexibility, and abstract reasoning, are necessary for a variety of tasks, including humor tests. The present study provides evidence for a relation between these cognitive processes - working memory, mental shifiing, and abstraction, and the appreciation of verbal humor. Significant correlations were obtained between mesures on tests assessing these cognitive processes and performance or, the Joke Completion test. A significant correlation was obtained between scores on the Alpha Span task designed to assess working memory (Craik, persona1 communication) and the number of errors on the joke Completion test. In fiontal lobe patients, there was also a significant correlation between the time taken to complete Part B of the Trail Making Test, a measure of both working memory and cognitive flexibility and the scores on the Joke Completion test. This indicates that working memory and cognitive flexibility are related to the ability to select the appropriate punchline to complete the joke stem. Worlong memory was hypothesized as being essentiai for successful performance on the Joke Completion test. Working memory, the ability to hold information on-line while it is being processed, was considered a part of the problem-solving functions of the frontal lobe, and therefore, important for the resolution stage of humor comprehension. It would be essential to keep information presented in the body of the joke in working memory, while the alternative ending types were being evaluated in order to find the punchline to cornplete the joke. That is, working memory would be essential for on-line monitoring and matching of ending types during the Joke Completion test. Cognitive flexibility was also hypothesized to be an essential part of the problem solving process during the resolution phase of the verbal comprehension process and would be important to view alternative meanings provided in the punchline.. The results of the study indicate that both working memory (on-line monitoring) and mental flexibility are related to performance on the Joke Completion test. Stuss et al. (1994) provide evidence that supports a role for the right frontal lobe in the monitoring of subjective experience. Their study assessed the capacity to organize verbal leaming after fiontal lobe injury by examining performance on list leaming tests. Right kontal patients were found to demonstrate excess intra-list repetitions. The authors interpreted these 'double recalls', i.e., recall of a word already recalled within a specific trial, as reflective of an impairnent in ongoinp editing process that assists a subject in remembering whether a word had been recalled in order not to recall it again. That is, they indicate that it reflected a disturbance in the on-line editing process and may be related to the impairment in sustained attention reported after nght fiontai pathology. The dominance of the right fiontal region for on-line monitoring reported by Stuss et al. (1994) may be related to the role of the fiontal regions in working memory. In the present study, a relation was found between working memory and the ability to choose appropriate punchlines to joke stems. On-line monitoring by the nght frontal regions may be particularly important in this ability, as reflected by the greater impairment exhibited by the right fiontal patients on the Joke Completion test. For patients with fiontal lobe lesions, a significant correlation was obtained between scores on the Proverbs test and the nurnber of errors on the Joke Completion test. The Proverbs test was employed to assess quality of thinking and abstract verbal reasoning (Lezak, 1983). The significant correlation indicates that abstract verbal reasoning was related to the ability to complete joke stems with the correct, fhny ending. The involvement of the cognitive processes of working rnemory, cognitive flexibility, and abstraction in hurnor comprehension in patients with fiontal lobe lesions is supponed by literature regarding the role of the fiontal lobe in these processes. Working memory has been considered to be a major hction of the fiontal lobe, and one that is implicated as being a cardinal process in mediating its role in the highest of cognitive functions (Baddeley, 1983; Baddeley and Wilson, 1988; Goldman-Rakic and Friedman, 1991 ; Fuster, 199 1). Recent data using PET imaging have also supported the role of the frontal lobes in working rnemory (reviewed in Buckner and Tulving, 1995 ). In addition to linguistic deficits (difficulty with figurative ianguage) and impairment in the cognitive processes of working memory, mental flexibility, and abstraction, a disturbance in certain aspects of emotional functioning, personality, and self-awareness after right fiontal lesions also parallel the hurnor deficit in these patients. A disturbance in social judgment, blunted social awareness, shallow affect, lack of awareness regarding own behavioral changes or deficits, deficient self-monitoring, are reported as features of personality change and an impairment in self-awareness in patients with right fkontal damage (Stuss, 1991 a, b). The reflective appraisal or evaluation of a situation or information, is required for humor comprehension and appreciation, and also forms an important basis for self-awareness. Right kontal damage appears to disturb such reflectiveness, contributing to impaïrments in humor and self-awareness. To summarize, the performance of the various focal lesion groups on the two verbal tasks used to assess humor appreciation (the Funniness Rating Scale and the Joke Completion Task) revealed a deficit in only right fiontal and bifrontal patients. Analysis of their pattern of errors on the Joke Completion Task suggested that in the right fkontal group, this was due to their greater attraction to merely surprishg or slapstick endings but failure to establish coherence, while in the bifrontal group, there might be a more pervasive disturbance. Performance of lefi hemisphere damaged (fkontal and posterior) groups, as well as, perfomance on Story Completion task, Mersuggested that, rather than being a linguistic deficit, verbal hurnor appreciation deficit in right fiontal and bifkontal patients might be a consequence of deficits in fiontal functions, such as the cognitive processes of working rnemory, mental flexibility, and abstraction. The humor deficit, therefore, appears to be a consequence of an impairment in the functions subserved by the frontal lobe. 3. Appreciation of Cartoon Humor The Cartoon Rating task assessed humor functioning in a situation where both verbal (captions) and nonverbal (pictures \ drawings) information was required to comprehend the humor present. In addition to tmly humorous items, where a cartoon drawing was accompanied by a hurnorous verbal caption, three types of foils were included in the task. These were cartoon drawings which were accompanied by verbal captions that, (1) featured slapstick content, (2) content associated with the drawing but was not hurnorous, and (3) content unrelated to the drawing. This task allowed an examination of whether the focal lesion groups could differentiate adequately between the truly humorous items venus the foils. In each case, the verbal caption had to be integrated with the cartoon drawing to assess whether hurnor was present, thus requiring processing of both verbal and nonverbal information in making the hurnor judgment. Results of the Cartoon Rating task indicated that there was no significant difference between the various focal lesion groups and the control group in their ratings of hurnorous items. The bifiontal group, however, rated the foils, i.e., items with slapstick captions and those with associated but unhy captions as being more humorous than the control group did. The bifiontal patients therefore, appeared to be more confûsed by the foils than the other focal lesion groups. In terms of the difference scores on the Cartoon Rating task, the bifiontal and right posterior patients failed to differentiate adequately between items with humorous captions and one type of foil, Le., items with captions associated with the drawing but which were nonhumorous. This confusion with associated captions is somewhat parallel to these groups' poor performance on the Story Completion task. Perhaps the bifiontal and right posterior patients expenence difficuIty on nonhumorous items with a foil which provides information relevant to the stimuli (e.g., ANS ending). To summarize the performance of the various groups on the Cartoon Rating task, in general, the patients did not exhibit significantly impaired performance compared to the control group. Bifiontal patients had the greatest difficulty on this task. In contrast to the verbal humor comprehension tasks, the right frontal patients were not significantly impaired. This could be due to the easier nature of this task, as well as the availability of information froom two different modalities. 4. Performance of Bifrontal Patients: Utilization Behavior BiFrontal patients demonstïated a unique pattern of behavior compared to other lesion groups on the humor comprehension tests- the Funniness Rating Scale, the Joke and Story Completion test, and the Cartoon Rating test. That is, only the bif?ontal patients showed a significant

attraction in ternis of their response to al1 alternative endings presented during the Joke and Story Completion test, as well as, in tems of ratings of funnuiess assigned to nonhumorous neutral and foi1 items during the Funniness Rating Scale and the Cartoon Rating test. This behavior may be a form of 'utilization behavior' that has been reported in frontal lobe patients (Lhermitte, 1983; 1986; Lhermitte et al., 1986). In tems of the pattern of errors on the Joke and Story Completion tests, only the bifiontal patients were nondiscriminating toward the endings selected. That is, in both tasks, patients with bifiontal lesions selected al1 available erroneous ending types significantly more frequently than did the control group and did not show a preference for one ending type unlike the other groups who made significantly more errors. On the Joke Completion task, only the right frontal and bifiontal groups made significantly greater number of errors than the control group. However, the right fiontal patients, when they erred, selected mostly HNS endings to complete the joke stems, whereas the bifiontal patients chose al1 three erroneous ending types - HNS, SF, and ANS. Similady, on the Story Completion test, only the bifiontal and right posterior patients made significantly more errors. Again, the bifiontal group selected both erroneous ending types available, HNS and ANS, while the right posterior patients selected only ANS endings. This behavior of the bifrontal group, i.e., selection of al1 alternatives provided in the situation, appears to parallel the 'utilization behavior' described in fiontal lobe patients in the literanire. A type of pathological behaviar, imitation behavior, where patients imitate the examiner's gestures, although not instructed to do so, has been described as the first stage of utilization behavior. Utilization behavior, an extension of the bilateral manual grasping behavior (rnagnetic apraxia), is obtained with miscellaneous utilitarian objects. That is, the tactile, visuotactile, and visual presentation of objects compels the patients to grasp and use them. These behaviors have been called 'environmental dependency syndrome', and pathology involving the front al 10 bes is responsible (Lhennitte, 1983; 1986; Lhermitte et al., 1986). Lhermitte (1986) suggests that imitation and utilization behaviors imply a disorder in personal autonomy. The patient's behaviors are described as striking, as though implicit in the environment was an order to respond to the situation in which they found themselves. Two determinhg features of the disorder are: dependence on (1) the social and (2) the physical environrnents. Loss of intellectual control was required for the occurrence of such behaviors. Either utilization behavior or imitation behavior were present in 96% of the 29 patients with focal lesions of the frontal lobes, particularly the inferior frontal lobe of one or other hemisphere (Lhermitte et al., 1986). These behaviors were interpreted as release of parietal lobe activities resultïng fiom impairment of frontal lobe inhibition. Shallice et al. (1989) differentiated two types of utilization behavior related to the demand characteristics of the situation. An incidental fonn occurred when subjects spontaneously used objects nearby when asked to do other tasks. Induced utiiization behavior occurred when the objects were given to the patient directly. These authors interpreted utilization behavior with their information processing mode1 of fiontal lobe fimction., Le., as a result of an absence in the Supemisory Attentional System due to impaired fiontal lobe functions. In the present study, during the Joke and Story Completion tests, the bifiontal patients selected al1 erroneous ending types significantly more kequently than any other patient group. This behavior might be interpreted in terms of utilization behavior. Lhermitte (1983) suggested that for fiontal lobe patients demonstrating utilization behavior, the presentation of objects irnplies the order to grasp and use them. Similarly, in the present study, to the bifiontal patients, the presentation of several alternative endings might have implied the order to select them (even if erroneous). This is similar to utilization behavior, an exaggerated dependency on the environment for behavioral cues. A similar compulsion to respond to stimuli in the environment may also explain the ratings of fbminess assigned by the bifrontal patients. On the Funniness Rating Scale, the bifiontal patients assigned significantly higher messratings to neutral items compared to the control group. Similarly, on the Cartoon Rating test, only the bifrontal patients assigned significantly higher hinniness ratings to foil items compared to the control group. With regard to utilization behavior, Lhermitte (1983) indicated that for the patients, the presentation of objects implies the order to grasp and use them. Thus, for the bifiontal patients performing the hurnor tasks in the present study, the presentation of alternative endings in the Joke and Story Completion tests, might have implied the order to select them. Similarly, the presentation of neutral and foil items dong with the humorous stimuli in the Funniness Rating Scale and the Cartoon Rating test, might have implied the order to rate them as being fünny.

5, Appreciation of Nonverbal Humor The Cartoon Array task was used to assess appreciation of nonverbal humorous displays. Ln particular, attention to visual detail was important to appreciate the humor on this task. Each stimulus consisted of an array of four cartoon drawings which were identical, except for one small visual detail. Of the four cartoons in an array, only one featured the visual detail which was essential to comprehend the humor, the other four cartoons featured nonhumorous details. Thus, ability to search and focus on the relevant visual feahue was essential for successful performance on this task. Minimal or no verbal information was present. Lefi fiontal, nght fiontal, bifrontal, and right posterior groups' performances were significantly worse compared to the control group. That is, they correctly identified significantly fewer of the correct cartoons (with the humorous detail) in the array as being the most humorous. The correlational association approach was used to investigate the cognitive processes related to the appreciation of nonverbal humorous displays. In particular, the relation between the cognitive processes of working memory, visual directed attention (visual search or scanning), and mental flexibility, and the appreciation of cartoon humor was examined. The Alpha Span test. the Trail Making Test, Letter Cancellation, and the Embedded Figures test, were employed to examine these cognitive processes. The correlation was significant for patients with frontal lobe lesions between the number of errors on the Cartoon may test and Parî B of the Trail Making Test, which was used to examine speed for visual search, attention, visuo-motor tracking, and mental flexibility (Lezak, 1983 ; Spreen and Strauss, 1991). Part B of the Trail Making Test has been shown to be sensitive to prefiontal lesions (Golden, 1981; Pontius, 1973) and can also be considered a measure of working memory and shifting. Similarly, for the £ionta1 patients, the correlations between the number of errors on the Cartoon Array test and the number of errors and the time taken to complete the Letter Cancellation task were significant. Further, the correlation between the number of errors on the Cartoon AiTay test and the scores on the Embedded Figures test was also significant for patients with fiontal lobe darnage. The significant correlations between perfomances on the Cartoon Array test and rneasures on these three tests indicate that cognitive processes measured by the Trail Making Test (Part B), Letter Cancellation test, and Ernbedded Figures test, are involved in successful performance on the cartoon humor test. That is, processes such as speed of visual search, visual attention, working mernory, and mental flexibility are related to the abilit. to search for the critical humorous detail in a cartoon drawing. The poor performance of the fiontal lobe (right, left and bifi-ontal) patients on the Cartoon Array task is in accord with the role of the fiontal lobes in attentional functions. The frontal lobes have been shown to play a major role in selective attention, as well as, in visual directed attention, which involves visual scanning, visual searching and control of eye movements (reviewed in Stuss, Eskes, & Foster, 1994). These attentional functions would be essential for successfu1 performance on the Cartoon Amy task. The right fiontal lobe, in particular, is especially important in sustained and directed attention (Stuss, Eskes, & Foster, 1994). The right posterior group's poor performance on this task may be a reflection of the role of the right hernisphere in attention.

6. Sense of Humor Participants were asked to rate their own sense of humor. This would provide information regarding their own self-evaluations and may be related to concepts of metacognition and self- awareness / self-reflectiveness. Right fiontal and bifrontal patients rated themselves as having a significantly lower sense of humor compared to control participants. This self-rating concemùig their sense of humor reflects their performance on the humor appreciation tests. That is, the nght fiontal and bifiontal groups demonstrated significantly poorer performances on the Funniness Rating scale, the Joke Completion task, and the Cartoon Array task. Their low evaluations regarding their sense of humor suggests that these patients were aware of their deficit in humor appreciation. The low self-ratings of the nght fiontal and bifiontal patients also parallels their muted emotional reactions during the administration of the humor tasks. As discussed in the earlier section, right frontal patients exhibited virtually no responses of facial mirth (smiles or laughs) throughout the test period. Bifiontal patients demonstrated significantly fewer mirth responses during the Joke Completion test. This result suggests an interesting possibility. Since the right fiontal and bifiontal patients were the only focal lesion groups to exhibit muted emotional reactions and were also the only groups to rate themselves as possessing a significantly lower sense of hurnor, these hdings suggest that they might rnonitor their own physical reactions, such as laughter, in making this self-evaluation. The Sense of Humor Questionnaire (SHQ) (Svebak, 1974) was also administered. This scale was designed to assess generalized individual differences in hurnor production and appreciation. It compnsed three subscales which assessed the three elements considered essential to sense of humor - (a) metamessage sensitivity (M), or the ability to recognize humor in situations; (b) persona1 liking of humor (L), or the enjoyment of humor and the humorous role; and (c) emotional permissiveness (E), or the tendency to fieely express one's emotion. Lefcourt & Martin (1986) have administered the SHQ in a number of studies with favorable results. For instance, they fond nonsignificant correlations between each of the subscales of the SHQ and the Marlowe-Crowne Desirability Scale, indicating that performance on the SHQ might not be subject to a social desirability bias (which might influence self-ratings). These investigators have also obtained favorable validity data for the SHQ. For instance, participants' sense of humor as rated by a good fiiend was found to correlate well with responses on the Metamessage Sensitivity and Liking of Hurnor subscales. Therefore, the responses of the participants in the present study on the SHQ would provide valuable information regarding different aspects of their sense of humor. Right fkontal and bifrontal patients obtained significantly lower scores on the Metamessage Sensitivity (M) subscale of the SHQ compared to the control group. This scale assessed the respondents' ability to perceive the humorous aspects of situations in the environment, Le., to "get the joke". The low scores of the right fiontal and bifkontal groups on this scale indicates that these patients view themselves as having a decreased ability to recognize the hurnor present in a situation. The low scores of the nght fiontal and bifiontal patients on the Metamessage Sensitivity subscale concurs with their inferior performance on the various humor cornprehension tasks. The right fiontal and bifiontal groups did not differ significantly fiom the control group on the other two subscales of the SHQ - the Liking of Humor (L) subscale, which assesses the degree to which respondents report they enjoy humor and place a high value on humor as opposed to perceiving it as being negative or undesirable, as well as Emotional Pemissiveness (P), which assessed the tendency to fieely express one's emotions. The Emotional Pemiissiveness (P) subscale contained items which right fiontal patients might be expected to endorse, given the clinical descriptions of these patients as demonstrating inappropriate behavior. Examples of items comprising this subscale include: (#9) I often find myself laughing in situations where laughter is quite out of place. (#13) 1 sometimes make mistakes in what kind of ernotional behavior is fitting in a particular situation. However, in the present study these patients did not differ significantly fiom the control group on this subscale. The finding that patients with frontal lobe lesions can make accurate self-evaluations is in accord with those reported by Miller (1989) who assessed the ability of patients with unilateral frontal lobectomies to describe their own self-perceptions, as well as to predict what a specific fiiend or relative would Say about them. Friends and relatives of the patients were also asked to complete a questionnaire in which they described a number of the patient's behavioral traits. Patients with fiontal lobe lesions described themselves as more impulsive, more cheerful, but less flexible than did patients with temporal lobectomies and normal control subjects. The nurnber of times that words chosen fiom two different perspectives were the sarne (i.e., patient's own and patient's prediction of own behavior by a relative), was also examined. The results revealed that patients with fiontal lobe lesions did not differ fiom the other groups (temporal lobectomy and normal control) in terms of (l)how well they predicted the opinion of a &end or relative, (2)how well their own self-perceptions matched their predictions of another person's opinion, and (3)how well their self-perception agreed with the other person's rating. This indicated that patients with fiontal lobe damage were aware of their own unusual behavior. The finding of no differences between groups in the ability to predict the opinion of a &end or relative was another indication that patients with frontal lobe lesions had a normal ability to judge themselves kom another person's perspective. The low self-ratings by right fiontal and bifkontal patients of their own sense of humor and scores on the Metamessage sensitivity subscale of the SHQ in the present study, when seen in light of these groups' infenor performance on the humor tests, indicate that the right fkontal and bifiontal patients were aware of their humor comprehension deficit. These patients appear to be capable of monitoring their own behavior (perhaps their physical reactions of mirth) in making self-judgments. These fmdings are similar to that of Miller (1989) in suggesting that patients with fiontal lobe damage are aware of their own impaired or unusual behavior. In the present study, fiontal lobe patients were not asked to predict what a fkiend or relative might Say regarding the patient's sense of humor. The ratings for patient's sense of humor were not obtained fiorn a person closely known to them. This should be examined in fiiture research on sense of hurnor. Patients should also be questioned regarding how they mived at the rating they assigned for themselves. For instance, will these patients indicate that they noticed that they did not laugh duing the testing or that they experienced difficulty in comprehending the hurnorous stimuli presented during the testing or in day-to-day social interactions. This would extend the results of the present study and would provide information regarding self-appraisal and metacognitive abilities of fiontal lobe patients. The results of the present study, like those of Miller (1989) indicate that patients with frontal lobe lesions are aware of alterations in their own behavior. However, this might contrast with the inability of fiontal lobe patients to modify their own behavior despite the ability to recognize abnormal traits in themselves. For instance, Konow and Pnbram (1970) made a distinction between emr recognition and evor evaluation on the one hand and error utilization on the other. A similar dissociation has been reported by Stuss (1 991a; b) in a patient wiih right fiontal lesion. While this patient had quite precise knowledge of her deficits and their effects, and could evaluate her situation, analyze the facts, and make appropriate recommendations regarding herself while role-playing as her own direct supervisor, once removed from her role-playing positions, she was no longer able to rnake the same judgments in relation to her real-life personal situation. That is, there might exist in fhntal lobe patients, a dissociation between thought and action. The low self-ratings for sense of hurnor and scores on the M subscale of SHQ by right fiontal and bifiontal patients in the present study indicates an awareness of humor deficit. However, they may not be able to use this information to guide or alter their problem behaviors. Alîhough this was not directly assessed in the present study, a large body of literature exists regarding a disorder of humor and laughter expression associated with firontal lobe damage. For instance, witzelsucht (an addiction to joking or the tendency to tell inappropriate jokes) and mana (silly, euphoric behavior) have been descnbed as key features of the 'frontal lobe syndrome' since the late 1880s (reviewed by Benton, 1991). This deficit in the expression of humor is often described as part of the personaliq and emotional changes that follow fiontal lobe damage (Stuss et al., 1992). Bogousslavsky et al. (1988) and Vardi et al. (1994) reported cases of patients with inappropriate laughing and perseverative, inappropriate j oking associated with right frontal dysfunction. In the present study, since Somation was not obtained fkom observers well-known to the patients regarding inappropriate expressions of hurnor and laughter, or personality / emotional changes in these patients, it is not laiown whether a dissociation might exist between these patients' self-evaluations of low sense of humor versus inappropriate expressions of humorous behavior. This is an issue which also needs to be examined in future research on humor in fiontal lobe patients.

7. Humor Production Two types of tasks were used to examine production of humor. Production of Hurnorous Captions was used to examine the ability to create humor. Ten cartoon drawings were presented and participants had to produce their own verbai captions which would make these cartoons funny. Tell a Joke and Read Jokes were used to assess language or narrative abilities required for hurnor production. These included both the capacity to tell a previously known joke (mernory for old humor), as well as, the ability to read jokes presented during testing. On the Production of Captions test, patients with fiontal lobe darnage obtained significantly lower ratings for sensibility and funniness of the captions they created. In terms of the location of brain damage, left fiontal patients obtained significantly lower rating for sensibility and bikontal patients were rated low on sensibility and funniness of captions. These results indicate that patients with fiontal lobe pathology were more impaired in creating humorous captions to cartoon drawings. It is important to note that even normal control participants found the creation of humorous captions a difficult task. This is indicated by the furininess ratings obtained by the normal participants for their captions. The captions created by the normal participants obtained a mean rating of 1.97 (a rating of 2 indicated 'slightly funny'). The highest mean messrating obtained by a control participant for the captions was 2.4. That is, no control participant was able to obtain a funniness rating beyond 'slightly funny'. This indicates that the creation of hurnor is a difficult process. Two tests, Tell a Joke and Read Jokes, were employed to assess narrative abilities related to humor production. Tell a Joke was used to assess narration and memory for old, familiar humor. Read Jokes was used to assess the narration of new humorous material. Certain narrative abilities are required for the successful telling of a joke. The person telling the joke has to be logical and maintain the proper sequence of events in the narration. Fust, enough information has to given during the early part of the joke, which will lead the Iistener to expect a particular, perhaps a conventional ending. If such an expectation is not built up in the listener, the arriva1 of the punchline will fail to produce surprise, an essential element in producing humor. Next, the punchline has to be presented at the appropriate tirne. If enough information is not supplied in the body of the joke, listeners will fail to make the appropriate inferences or fail to appreciate the connection between the body of the joke and the punchline, Le., establish coherence, the second essential element in joke comprehension. As Weylman et al. (1988) indicated, telling a joke necessitates knowing how to sequence parts into a whole and to prepare listeners for the punchline. Careful, deliberate exposition of narrative (giving enough, but not too much, information) sets up the nght cues for the punchline to succeed. In addition, the jokes should be narrated using the appropnate tone, prosody, intonation, and gestures. In the present study, a greater proportion of right fiontal and bifiontal patients failed to recall and narrate any joke. This indicates that memory for old, familiar hurnor may be impaired by frontal lobe pathology. In addition to the failure to recall any farniliar humor, the jokes recalled by the right fiontal patient and one bifiontal patient were of poorer quality in tems of their namation. That is, in these patients, the joke-telhg was not direct, they did not provide sufficient background information so that the punchline would produce surprise, and their jokes did not have an obvious punchline. Aiso, the punchline could not be reconciled with the body of the joke to establish coherence in the narrative. Thus, both elements necessary for successful humor, surprise and coherence, were deficient in the jokes narrated by these patients. Further, the jokes were rated as being less logical and less Mycompared to the control participants, lacking in the appropnate prosody and intonation needed to convey humor. Two right temporal patients obtained lower ratings for joke narration on some rneasures. Their jokes were rated as being less logical and less funny compared to that of control participants. These results indicate that nght hemisphere pathology (in nght fkontal, bifiontal, and right temporal patients) produced an impairment in the narrative abilities required for hurnor production. This impairment was more severe in patients with right fkontal damage (i.e., nght ftontal and bifrontal). The deficit in humor production or joke-telling in right hemisphere patients, particularly in those with right fkontal damage in the present study, is in keeping with the impairments in certain language and narrative abilities reported in the literature in these patients. The right hemisphere has been shown to play a critical role in pragmatic language which deals with the uses of ianguage, as weli as in paralinguistic capacities, Le., those aspects of tone and gesture that accompany language, and hurnor requires such abilities (Weylman et al. 1988). Ross (1 98 1; 1993) accorded the right hernisphere a dominant role in the affective components of language, which include spontaneous affective prosody and emotional gesturing. The functional-anatornic organization of prosody and emotional gesturing in the right hemisphere was suggested to minor that of propositional language in the left hemisphere. He reported cases of patients with lesions Uivolving the right frontal regions who displayed motor aprosodia. The features included flat and monotonous speech with little spontaneous prosody and greatly reduced or absent spontaneous gesturing, giving them a flat affect. A deficit in the paraluiguistic functions of spontaneous prosody and emotional gesturing will result in a failure in conveying hurnor. This is reflected by the low ratings obtained by the right hemisphere patients for successfûl joke-telling in the present study. Ln addition to deficits in paralinguistic capacities, patients with right hemisphere damage display impairments in spontaneous narrative discourse. They often display disorganization in the topics they convey in spontaneous speech (Delis et al., 1983). Their spontaneous speech is often described as excessive and rambling; their comments may be off-color and their humor primitive and inappropnate; they tend to focus on insignificant details or rnake tangential remarks; and the usual range of intonation is fiequently lacking (Gardner et al., 1983). Recent experirnental work has provided evidence to support the importance of the right hemisphere to the discourse function of language. Wapner, et al. (1981) fomd that the right hernisphere patients had difficulty both in integrating the elements of a story and in appreciating the 'narrative fond of a story, although they exhibited no difficulty in straight linguistic processing, such as, using appropriate phonology and syntax, and recalling elernentary facts. The nght hemisphere patients were markedly impaired in organizing story elernents logically; infening the correct point or moral of a story, tending either to simply repeat the plot or give a literal response; and accounting for character motivations. Further evidence of a lack of sensitivity to narrative form in right hemisphere patients was the abundance of embellishments or extraneous and unnecessary comments or additions to the story, and confabulations, which were more fiequent in those with anterior or fiontal lesions. Right hemisphere patients also had difficulty in reacting appropnately to noncanonical or bizarre story elements, recalling these elements better and adding explmations to justifi their inclusion in the story. Delis, et al. (1983) also found that patients with right hemisphere darnage had dificulty organizing complex linguistic material. i-e.. in rearranging mixed-up sentences compnsing a story. Their study indicated that right hemisphere processing is important for the organization of language at the paragaph level and to integrate complex units into coherent wholes, i.e., in organizing linguistic information at the narrative level. Joanette, et al. (1986) investigated the narrative abilities of right hernisphere patients in a more natural narrative task than that used by Delis, et al. (1983). In this study, subjects were shown an illustrated version of a story and asked to tell the story. The oral narratives were then submitted to a 'propositional analysis' in order to denve a description of the amount, the nature, and the organization of their informative content. Right hemisphere patients' narratives contained a smaller arnount of information, mostly pertaining to the 'complication' part of the story. This study indicated that right hemisphere damage affects more the content than the fom of narrative discourse, showing that the integrity of the right hernisphere is needed for 'normal' discourse abilities (Joanette, et al., 1990). The above studies have shown that the right hemisphere is important in verbal communication or narrative discourse. Right hernisphere damage can produce impairments resulting in a lack of information provided about the topic being narrated (Joanette, et al., 1986; 1990), as well as, the intrusion of embellishments and confabulations into the narrative (Wapner, et al. 198 1). Reviewing the relationship between frontal lobe and language, Alexander, Benson, and Stuss (1989) reported affective dysprosody, defective pragrnatic discourse, decreased output, disordered formulation, tangential discourse, and confabulation in patients with right fiontal damage. Such deficits in narrative discourse abilities must affect humor production, such as narrating a joke. In the present study, patients with right hemisphere, especially nght frontal, pathology, showed impairments in narrating jokes. Their jokes were not told directly and included extraneous or unnecessary information, similar to the results reported by Wapner, et al. (1 98 1). These patients failed to provide sufficient idornation to set up the joke resulting in a failure of the punchline to produce surprise. This is similar to the lack of information provided in the narration of a stov reported by Joanette, et al. (1986; 1990). The right hemisphere patients also obtained low ratings for success in telling the joke and funniness of the joke, since their joke- telling was not accompanied by appropriate prosody and intonation, that is, a deficit in the affective components of language reported by Ross (198 1; 1993). Therefore, the results of the present study indicate that deficits in verbal communication or narrative discourse reported in patients wiîh nght hemisphere pathology affects their ability to produce humor, such as narratïng jokes.

8. Humor and A~ing Humor is reported as being valued particularly highly by the aged and as having great potential for the study of aging (Nahemow, 1986). There is growing recognition and acceptance of the importance of humor in the care and the lives of the elderly. However, it has not been the focus of rnuch scientific investigation in relation to the aged. The present study exarnined appreciation and comprehension of verbal and nonverbal humor and the cognitive process involved, in a normal aging population. A study of hurnor in aging is especially relevant in a neuropsychological context. Evidence is accurnulating regarding structural, chernical, and functional changes in the frontal lobe associated with normal aging (e-g., Albert & Stafford, 1980; Coffey, et al., 1992; De Santi, et al., 1995; Murphy, et al., 1996, reviewed earlier). There have also been arguments suggesting hernispheric asymmetry in fkontal detenoration with age, since the performance of the elderly on some neuropsychological mesures have been found to be similar to that of patients with nght fkontal darnage (Kaplan, 1980; Stuss, et al., 1996). Since the present study examined the brain regions involved in processing hurnor with the hypothesis that the fiontal lobe, particularly the right fiontal region, was important to humor, an examination of hurnor in the elderly would provide additional information regarding frontally mediated functions in the aged. The performances of normal aged participants on a variety of tests designed to assess verbal and nonverbal humor appreciation and comprehension were compared to that of young participants. In addition, some of the cognitive processes necessary for humor comprehension were examined, particularly those mediated by the fiontal lobe, such as working memory, cognitive flexibility, visual search, scanning, and focused attention. The main findings were: 1. The elderly participants assigned significantly higher funniness ratings compared to the young on al1 humor tests. 2. The older participants made significantly greater number of errors on the verbal Joke Completion test. 3. The aged made significantly more errors on the nonverbal Cartoon Rating test. 4. Performance on tests assessing cognitive processes mediated by the fiontal lobe were correlated with performance on humor tests.

Funniness Ratin~s: The older participants assigned significantly higher ratings of funniness on dl humor tests compared to young participants. On the Funniness Rating Scale, the elderly rated both humorous and neutral stimuli as being funnier than did the young. On the Cartoon Rating test, the aged assigned significantly higher funniness ratings to humorous stimuli, as well as to foils - associated captioned and unrelated captioned items. Sirnilarly, on the Joke Completion and Cartoon Array tests, the older participants rated the items they answered correctly as being funnier compared to the young. Although the elderly rated both humorous and neutral / foi1 items as being funnier on the Funniness Rating Scale and the Cartoon Rating test, they distinguished adequately between tnily humorous and nonhumorous items. That is, on the Funniness Rating Scale, the difference scores between humorous and neutral items were not significantly different fiom the young indicahng that the elderly differentiated between these two types of stimuli. Sirnilmly, on the Cartoon Rating test, the difference scores of the elderly did not differ fkom the young for associated- captioned and unrelated-captioned items, indicating again that they differentiated between the humorous cartoons and two types of foils. Oniy the difference scores for slapstick items were significantly different. These results indicate that although the older participants viewed the humorous stimuli presented in the test as being significantly funnier than did the young participants, they had no impairments on the Funniness Rating Scale and the Cartoon Rating test. That is, their difference scores, a more direct measure of their ability to differentiate between humorous and neutral items generally did not differ fiom those of the young. The only difference score that was significant was for slapstick items on the Cartoon Rating test suggesting that perhaps the elderly have a greater appreciation of slapstick compared to the young and therefore do not differentiate in funniness between humorous and slapstick stimuli to the same extent as the young. The aged participants, in addition to their difference scores, also did not differ sigriificantly fÏom the young in tems of their mirth responses during the humor tests except on the Joke Completion test. That is, the elderly responded to the humorous items with srniles and laughs in a manner corresponding that displayed by the young. Physical / emotional reactions to humorous stimuli are also a measure of humor appreciation and comprehension. Thus, the rnirth responses of the elderly, like their difference scores, indicate no impairment on the Funniness Rating Scale and Cartoon Rating test. The significantly higher ratings of messassigned by the elderly on the humor tests compared to the young suggest that there may be differences in the type or content of humor that is preferred by the young versus the aged. The type of stimuli selected in the present study, for instance cartoons by Unger, may have been more appealing to the elderly. Although the preferences of the young and the aged in ternis of humorous content was not systematically investigated in this study, it was noted that the elderly sometimes spontaneously mentioned during the test administration that they liked cartoons by Unger. The kind of humor that the elderly particularly enjoy should be exarnined. As noted in the introduction, hurnor is increasingly being advocated as being beneficial in the care of the elderly. It has been suggested that hurnor has significant positive effects on major biological systems and haç been recommended as a coping rnechanism for successfùlly dealing with disadvantageous circumstances, addressing some health needs, and for improving life quality for the elderly (Fry, 1986). The utility of Uitroducing humor in the geriatric setting by the caregivers through activities such as use of a hurnor file, clowning, joke-of-the-week, humor journals, joke swaps, and humorous films and TV programs has been recornmended (e.g., McGuire et ai., 1992; Tennant, 1990). In order for these techniques to be effective, the humor that is selected must be meaningfûl and enjoyable to the target audience. Therefore, it is important to examine the kinds of humor that the elderly have special preference for.

Joke Completion Test: The older participants made a significantly greater number of errors on the Jolce Completion test. This test was employed to examine the cognitive processes necessary for hurnor comprehension and is based on the Incongruity-Resolution rnodel of humor. According to this model, there are two stages in humor comprehension - in the first stage incongmities are recognized; these are then resolved in the second stage. Therefore, successfûl performance on this test required a sensitivity to the element of surprise in humor (stage l), as well as the

capacity to establish coherence (stage 2) (Bihrle et al., 1986; Brownell et al., 1984). In addition, the Joke Completion test along with the Story Cornpletion test, exarnined whether a deficit in verbal humor was a consequence of a deficit in language comprehension, especially involving narrative language, by comparing performance between the Joke and Story conditions. The Joke Completion test required participants to complete joke stems by selecting fiom arnong four alternative endings the only correct funny choice which was the original punch line. The elderly participants answered significantly fewer items with the correct punch line indicating an impairment on this test compared to the young. This impaKed performance of the aged was similar to that of patients with fiontal lobe lesions who also demonstrated an impairment on this task, in contrast to those with nodiontal lesions. The Joke Completion test was also designed to enable an examination of the reason for failure on the test, which was accomplished by analyzing the incorrect alternatives chosen to complete the joke stem in place of the correct punch line. Thus, choice of HNS or ANS endings indicated that the individual retained a sensitivity to surprise, the first element required for humor comprehension according to the Incongniity-Resolution model, but lacked the ability to establish coherence, which is the second stage. In contrast, choice of SF endings indicated the opposite pattern, Le., it reflected a deficit in the first stage or an inability to appreciate the importance of surprise in humor, but intact functioning of the second stage, the ability to establish coherence. An examination of the incorrect alternatives selected by elderly participants showed that when they erred, they chose HNS and SF endings significantly more often compared to the young. This pattern of does not indicate a clear deficit in either the firt or the second stage of humor comprehension. The story Completion test was designed to be used in conjunction with the Joke Completion test in order to examine whether an impairment in humor comprehension observed on the Joke Completion test was due to a deficit in narrative language abilities. It allowed an examination of whether participants knew when surprise was appropriate and when it was not. The elderly participants did not differ significantly kom the young in their performance on the Story Completion test. That is, they were able to select appropriate straightforward, logical, and coherent endings to complete the story stems. This indicates that the aged did not have any difficulty with narrative language. The impairment in verbal humor demonstrated by the eiderly on the Joke Completion test is in contrast to their normal performance on the Funniness Rating Scale and the Cartoon Rating test. The Funniness Rating Scale and the Cartoon Rating test oniy required participants to read and rate the stimuli. However, in the Joke Completion test, the participants were required to select the correct ending or the original punch line fkom arnong several alternatives. This was a more dernanding test of humor comprehension and therefore the elderly rnight have had greater difficulty on this test. Schaier and Cicirelli (1976) studied appreciation and comprehension of humor in elderly subjects. The rationale for the study came fÎom previous research with children that provided evidence for the cognitive congruency principle which indicated that an inverted-U relationship exists between messand cognitive difficulty, Le., an optimal moderate amount of cognitive chaIlenge is associated with maximal appreciation of hurnor (McGhee, 1976). The Schaier and Cicirelli (1976) study was based on the cognitive congruency principle, as well as evidence that suggested diat early developments in logical thinking may be subject to regression and disorganization in old age. That is, there were studies indicating that elderly persons may have a level of cognitive fiinchoning on Piagetian tasks similar to that of young children and may fail on some conservation tasks. Therefore, Schaier and Cicirelli (1976) used a Piagetian framework to compare humor comprehension in three age groups - 50-59,60-69, and 70-79. Subjects were tested on their appreciation and comprehension of 12 conservation and 12 nonconservation jokes. The conservation jokes depended on the Piagetian concepts of conservation of mass, weight, and volume for their comprehensior.. Cognitive ability of the subjects on the conservation ta& was also tested. Appreciation of jokes was found to increase and comprehension of jokes decreased as subjects' age increased; thus the oIder subjects tended to understand the jokes less well, but to think they were funnier. This was accompanied by a decline with age in the subjects' ability to conserve volume on Piagetian tasks. The results of the study were interpreted as support for the cognitive perceptual theory of humor in old age, with appreciation of a joke depending on a match between an individuai's ability level and the cognitive demand of the joke. The authors suggested that in the latter part of the life-span, cognitive ability and joke comprehension begin to decline with age although evidence was fomd only for conservation of volume. There is an increase in the cognitive demand of the joke, leading to greater appreciation. They further speculated that as cognitive abilities decline still Merwith age, there would again be a match between ability level and cognitive demand of the joke, leading to a level of maximum appreciation. Beyond this point, additional decline in ability would lead to a decline in appreciation because the individual does not understand the joke (inverted-U). in the present study, older participants were impaired in their performance on the Joke Completion test. Based on Schaier and Cicirelli's findings, we may question whether the elderly found this test more difficult compared to the Funnlliess Rating Scale and the Cartoon Rating test where the aged participants demonstrated no impairment. One indication that the elderly might have found the Joke Completion test more difficult than the Funnuiess Rating Scale and the Cartoon Rating test is that only this test the elderly demonstrated significantly fewer mirth responses, Le., a muted physical reaction. McGhee (1976) had suggested that spontaneous smile- laugh responses may also bear an inverted-U relationship to cognitive challenge. Though the results of his study did not provide clear support for the cognitive congruency pnnciple for overt expressions of affect in response to hurnor stimuli, he found that requiring children to make judgments about how funny the stimuli are or why they are hyaffected their smile-laugh reactions and confounded the results. We may tentatively raise the question as to whether the depressed physical / emotional reactions of the elderly on only the Joke Completion test indicates that they found this test cognitively more challenging compared to the Funniness Rating Scale and the Cartoon Rating test. The impairment in humor comprehension dernonstrated by the aged on the Joke Completion test parallels that of patients with fiontal lobe lesions, who were the only focal lesion group with a deficit on this test. It also appem to be related to the performance of the elderly on certain cognitive tasks, especially those assessing fùnctions rnediated by the frontal lobe, such as working rnemory and cognitive flexibility. This suggests that the deficit exhibited by the older participants on the Joke Completion test may be related to fiontal lobe dysfûnction. The performance of the older participants on two measures of working memory, i.e., scores on the Alpha Span test and the time taken to complete Part B of the Trail Making Test, correlated significantly with the number of errors on the Joke Completion test. This indicates that working memory was related to the ability to select appropriate punch lines to complete the joke stems. Working memory has been considered to be an important hction of the fiontal lobe (Baddeley, 1986; Baddeley and Wilson, 1988; Goldman-Rakic and Friedman, 199 1; Buckner and Tulving. 1995; Moscovitch, 1989; 1992; Moscovitch and Winocur, l992a, b). The present study did not directly assess whether the elderly demonstrated a deficit in working memory compared to the Young. However, Moscovitch and Winocur (1992, 1995) in their reviews suggested that the type of memory deficits observed in the elderly was a working- with-memory deficit, which captured the essence of the impairment associated with frontal lesions. The results of the present study indicate that working memory mediated by the fiontal lobe is related to the poor performance exhibited by the elderly on the Joke Cornpletion test. Cognitive flexibility or mental shifting was also related to the performance of the elderly on the Joke Completion test. This study theonzed that cognitive flexibility and abstract reasoning would be required for problem solving in humor. They are also considered to be frontal lobe functions. For instance, idexibility, rigidity, or perseveration are reported to be particularly rnarked following prefiontal lesions (Walsh, 198 7). In the Joke Completion test, problem solving was considered to be necessary for resolving incongruities and for establishing coherence between the joke stem and the punch line. This requires abstract reasoning and flexibility in thinking which allows the participant to assess the alternative endings and their meanings in order to select the one that makes the punch line congruent with the body of the joke. In the present study, the Trail Making Test and the Wisconsin Card Sorting Test were ernployed to assess cognitive flexibility and shifting of set. The time taken to complete Part B of the Trail Making Test, a measure of mental shifting, correlated significantly with the number of errors made by the elderly on the Joke Completion test. This indicates that cognitive flexibility was related to the ability of the older participants to select appropriate punch lines. Thus, the poor performance of the older participants on the Joke Completion Test correlated with processes mediated by the fiontal lobe - working memory and cognitive flexibility or mental shifiing. This suggests that fiontal lobe functioning in the eIderIy is related to verbal humor comprehension as assessed by the Joke Completion test. Nonverbal Humor - Cartoon Arrav Test: The older participantsy performance was impaired compared to the young on the Cartoon Array test. The elderly group made more errors in selecting the funny choice fkom among an array of four cartoon pictures. Al1 four cartoons in an array were essentially identical except for a critical humorous detaiI which was only present in the correct choice, while the other three incorrect alternatives featured nonhumorous details. The poor performance of the aged group indicates that they had a difficulty in conducting a visual search of the cartoons and focusing on the relevant critical humorous detail. Like the Joke Completion test, functions mediated by the fiontal lobe may be related to the performance of the older participants on the Cartoon Array test. The scores obtained by the elderly on the Cartoon Array test showed trends of being conelated with rneasures of psychological processes, Le., with scores on the Alpha Span test and the tirne taken to complete Part B of the Traii Making Test. However, these correlations fell slightly below significance level of the criterion selected for this study (being around -03). This indicates that working memory, mental shifting, and directed visual attention may be related to the cornprehension of cartoon humor. These correlationaI trends, as welI as the significant correlations between the fontal lobe functions of working memory and cognitive flexibility and the Joke Completion test indicate that fiontal lobe functioning may be related to both verbal and nonverbal humor appreciation in the elderly participants. 9. Theorv of Humor and the Frontal Lobe The present study examined hurnor appreciation and production in patients with damage to specific brain regions. Patients with pathology involving the frontal, particularly nght frontal, regions were irnpaired in processing humor. Results of the study lead to a conceptualization of the relationship between humor and fiontal lobe damage in tems of an integration deficit in fkontal lobe patients. Humor is a multifactorial hction. Therefore, the ability to inteprate information fiom disparate sources is important to humor. This integration of information is an important function of the fiontal lobe and can occur at different levels or hierarchy of fiontal lobe functioning. Three curent theones/models attempt to provide a fiamework for understanding the psychological deficits that are observed in humans following darnage to the frontal lobe. The application of these to the findings of this study are discussed. Grhan (1989) proposed a model of higher-order cognitive processing to account for the deficits in reasoning, memory, and interpersonal behavior observed in patients with fkontal lobe lesions. This is a model of frontal lobe knowledge representation (or the kind of information subserved by the fiontal lobe), in which 'managerial knowledge units' OW(Us) are said to represent large-scale howledge units that are somewhat analogous to schemas, scripts, and fiames. The MKU system consists of a hierarchy of MKUs that range from the concrete to the abstract, covering almost al1 aspects of human behavior. Appropriate MKUs would be activated by a system similar to that proposed by the Norman and Shallice model (described below), Le., by environmental stimuli via the supervisory attentional system or by priming via the contention scheduling system. Thus, according to this model, alrnost al1 aspects of human behavior are under the control and guidance of a hierarchy of MKUs and the type of deficit observed following frontal lobe lesion corresponds to the type of MKU that is damaged. This model may be applied to some aspects of hurnor appreciation. As Brownell et al. (1983) suggested, a schema or script covering the normal course of events provides the background against which the incongruity in humor is detected. However, it is difficult to explain a humor deficit in terms of damage to particular MKUs, to determine which MKUs are involved in humor, or even whether humor cmbe considered as a knowledge unit. Humor is complex and involves many processes that are considered generic and applicable to many MKUs and with this model it is difficult to reconcile the cognitive with the affective dimension of humor. Shallice ( 1982; Shallice & Burgess, 1991 ) proposed an information-processing model of brain function. It consists of four components: (1) Cognitive units, which are brain functions related to specific anatomical systems (e.g., language, visual-spatial). (2) Schemas, which are behavioral activities above and beyond the cognitive units, that demand integration of multiple cognitive units for their accomplishments. Though goal-oriented, schemas are usually routine, leamed, rehearsed, highly specialized programs for controlling overlearned skills. (3) Contention scheduling, which is the selection of appropriate schernas for combinations of routine behaviors by triggers activated by sensory perception or the output of other schemas. It is primarïly important for relativeiy rapid, routine selection based on specific niles. (4) Supervisory attentional system (SAS), whose purpose is to handle nonroutine goal achievement in a slow but flexible manner. The SAS operates when contention scheduling fails or when there is no known solution. In the onginal conception of the model, the supervisory system was seen as an information processing system which was unitary and not fiagnented into different cornponent systems. Recently, Shallice's approach has been integrated with that of Stuss and Benson and is presented below. Stuss and Benson (1986; 1990) proposed a hierarchical behavioraVneuroanatomical model of brain function that emphasized the role of the fiontal lobe in the control of al1 brain functions. In this model, most classic cognitive functions such as rnemory, attention, and language, have maximum representation in the posterior-basal brain regions. The £?ontal functions, interacting with these posterior-basal hctional domains, are divided into three levels. The fint level includes the functions of drive or activation and sequencing. At this level, sequencing involves the ability to handle multiple bits of information in an accurate senal order. The ability to extract relevant uSormation fkom the sequences and place it into new sequences of information is a related function. Finally, it also involves the taking of information fi-oom sequences and integrating it with old, previously learned information. Thus, sequencing and integration are important frontal functions at this level of the hierarchy. The next level of prefiontal function consists of executive or control functions of anticipation, goal selection, preplanning, initiation of novel responses, and monitoring. In this model, the emphasis is on dissociation of processes. hportantly, there is a major interaction of these separate processes with the postenor systems, with the fiontal lobe processes acting in a supervisory or control capacity. Finally, self-awareness is considered to be the "highest" of al1 integrated brain activities. The theory ranks self-awareness (self-reflectiveness, self- consciousness) as the highest attribute of human behavior and one of the most mysterious (Stuss & Benson, 1989). This highest level of mental functions is believed to be organized in the frontal poles, and integrates a person's role in the broader context of society. Stuss and Shallice (Stuss et al., 1995) have extended their models and presented a new approach to the study of frontal lobe functioning based on the theoretical framework of the supervisory system model of Norman and Shallice (descnbed above). The major idea emphasized by their approach is that the supervisory system is not a unitary process, but cm be fractionated into component processes. Therefore, it is important to look for associations / or dissociations among hypothesized processes related to the fiontal lobe. The utility of this approach was illustrated by the example of attention. The control of attention was shown to consist of several types of tasks (e.g., sustaining attention, switching attention). The processes involved in each task were characterized in terms of the supervisory system model and converging evidence 60m neuropsychology, anatomy, and physiology were used to support the existence of these separate supe~soryprocesses. This approach has also been applied to fractionate self-awareness (Stuss, et al. in press). This new approach (Stuss, et al., 1995) ernphasizes that the fiontal lobe and the supervisory system do not function as a simple unitary systern. The fkontal lobe has extensive reciprocal connections with virtually al1 other brain regions. Therefore, it may be unique in the quality of the processes that have evolved, and in the level of processing , performing an executive or supervisory role. The different regions of the frontal lobe provide multiple interacting processes. It was suggested that because the level of processing in the fiontal lobe allows the integration of information fiom other brain regions and because of the complexity of the fiontal structures, the interacting processes provide a sophisticated control of braùi fimctions. The authors suggest that this approach can be adapted to brain functions where the fiontal lobe plays a major role, such as attention and self-awareness, explaining these fûnctions in tems of multiple interacting simple processes. Thus, in the Stuss and Benson model and in the latest refinement of this model (Stuss, et al., 1995; Stuss, et al. in press), integration of different sources of information is an important fkontal function, at different levels of the hierarchy. Hurnor is related to dissociable executive or cognitive processes, such as language and working memory. Humor is also related tc episodic mernory and self-awareness. The frontal lobe acts in an executive or control capacity. coordinating and integrating these processes. nius, the hierarchy of frontal fùnctions and the integration involved at each level can be applied to hurnor. Hurnor requires the integration of several processes. Integration in humor involves language, for instance, the ability to see altemate meanings or interpretations of the humorous stimuli. A deficit in integration in the realm of language has been suggested by investigators who have examined pragmatic aspects of communication in brain damaged patients. in these studies, patients with nght hemisphere pathology were impaired. Wapner et al. (198 1) reported that right hernisphere patients exhibit a striking amount of difficulty in handling cornplex linguistic materials and noted that they have clear difficulties in integrating specific infomation. Right hemisphere patients were suggested to have impairments in handiing complex linguistic entities, ones which entai1 redundant information, noditeral information, and information which requires integration across the boundq of the word or clause (e-g., jokes and stones). Foldi (1987) put forth a similar hypothesis as one of the explanations for a right hemisphere deficit in pragmatic appreciation of linguistic material. She suggested that right hemisphere patients may fail to 'integrate' the necessary components of information in order to arrive at a felicitous indirect interpretation. That is, the task of successfully interpreting indirect acts requires the integration of assorted pieces of information. In a communicative setting, a person will derive numerous cues from several rnodalities and, in order to appreciate the social connotations, he or she must simultaneously take al1 cues into consideration. These must then be integrated in a meaningful, hierarchic fashion so as to appreciate the interpretation of the indirect act. The right brain damaged patients may be impaired because they may fail to judge more than one component at a time, or because they may have ordered the relative importance of a component into a different hierarchy than normal subjects. Thus, the nght hemisphere is important for simultaneously organizing and integrating different elernents of a conversation (Foldi, et al., 1983). An integration deficit in the narrative and verbal context has been offered to account for the performance of nght hemisphere damaged patients in humor cornprehension. Brownell et al. (1983) suggested that the inability of right hemisphere patients to integrate the body of a joke and its ending into a coherent interpretation may indicate an inability to integrate content across parts of a narrative. This integration deficit at the nanative language level was observed in the present study on the Joke Completion test in patients with frontal lobe pathology. Only fiontal patients, particularly those with right fiontal (including bifiontal) darnage were impaired. Alexander et al. (1989) provided evidence indicating the relevance of the frontal lobe in discourse and narrative functions. The eontal lobe performs a supervisory function, such as rnaintaining comectedness and relevance in a narrative by the application of attention and self- critical observation. In particular, right fiontal damage was related to disruptions in affective or pragrnatic intent with deficits involving the use of sarcasrn, indirect requests, or humor. That is. the right fiontal region is involved in control functions involving figurative and narrative language. Thus, a deficit on the verbal hurnor appreciation tests in this study may reflect an integration deficit involving language in right frontal patients, a deficit in its executive control over language. In addition to integration of information relating to language, hurnor also involves the integration of current incoming information, such as a joke, with past experience and knowledge. Brownell et al. (1983) suggested that apart fiom an intact understanding of the ordinary meanings and uses of language, an individual must also possess a schema, or script, which covers the normal course of events. Against this background, the individual must be able to detect discrepancies fiom the normal course, i.e., sensitivity to surprise, the fist component of the Incongruity-Resolution model of humor. The second component, coherence, requires the integration of different perspectives or alternative interpretations, so that the punchline cm be tied coherently to the body of the joke. Thus, the first stage of humor appreciation involves the integration of information contained within the joke to the individual's knowledge and past expenence, while the second stage involves integration of the punchline with the body of the joke (an integration at a narrative language level, as discussed). This integrative function corresponds to the next level of fi-ontal functioning in the hierarchical model of Shiss and Benson, i.e., the capacity to sequence, as well as to take information fkom sequences and integrate it with old, previously learned information. This involves working memory, the ability to handle multiple bits of information in an accurate serial order, similar to that proposed by Fuster (1980), the integration of temporally ordered infomation with prior Imowledge. In the present study, working memory was associated with poor pe~omanceon hurnor appreciation tests indicating a deficit in integration at this level of fiontal functioning. At this level of integration, another function of the frontal lobe is important, Le., episodic memory - memory that mediates remembenng of personally experienced events. Tulving (1989) using blood flow measurements suggested that episodic memory is frontal in localization. Wheeler, et al. (1995) performed a meta-analysis of studies which used tasks of episodic memory, recognition, cued recall, and f?ee recall. Frontal pathology disrupted performance on al1 three types of episodic memory tests. In humor, information fkom the current humorous stimulus must be interpreted in light of the individual's knowledge and past expenence. This requires episodic memory and the integration of current humorous stimulus with information from persona1 mernories retrieved kom episodic memory. Episodic rnemory has been associated with self-awareness, the highest of frontal lobe functions according to the Stuss and Benson model. There is growing emphasis on the importance of the fiontal lobe in episodic memory and self-awareness. Tulving (1985) proposed three varieties of consciousness, anoetic (non-knowing), noetic (knowing), and autonoetic (self- knowing). Autonoetic awareness or autonoetic consciousness correlated with episodic memory and was considered necessary for the remembenng of personally experienced events. Wheeler et al. (1997) argue that autonoetic consciousness represents both the major defming feature of episodic memory and also the highest mental fùnction of the frontal lobe. One of the most distinguishing characteristics of episodic memory is considered to be its critical dependence upon autonoetic awareness and they argue that prefiontal cortex plays a vital role in making autonoetic awareness, and thereby, episodic memory, possible. That is, fiontai lobe plays a critical role in the episodic system, especially in the regulation of autonoetic awareness. A disturbance in self- awareness/autonoetic awareness is reported to result in an inability to apply available knowledge to oneself, inability to internatize howledge at a self-reflective or personal level, i.e., a sharp dissociation between knowledge (and executive functions) and the realization of persona1 relevance of that knowledge. That is, frontal lesions disturb the capacity for autonoetic consciousness, a disturbance that is manifested in many ways besides episodic memory. Self-awareness is also important in humor. At the highest level of integration, humor is associated with abstract self-referential capacities, such as self-awareness, self-control, self- analysis, and self-consciousness. Humor involves the ability to view and evaluate an event fiom different perspectives, making use of past penonal history, which requires self-andysis and self- referential capacities. At this level of the hierarchy, fiontal function involves the integration of exteroceptive, information fiom the outside world and interoceptzve, information from the internal feeling states (Nauta, 1973). This involves integration of cognitive with affective information and may be important in the social and affective role of the frontal lobe, Le.. in integrating a person's role in the broader context of society (Stuss, et al., 1997). Stuss, et al. (in press) proposed a hierarchy of consciousness, with self-awareness occumng at the higher levels. This mode1 involves the fiactionation of consciousness into different levels. The fiontal lobe is important at the higher levels of the hierarchy, mediating the executive fictions that integrate the information provided by the sensory systems and organinng goal-directed behavior. The final level of self-awareness was related to the fiontal lobe and its limbic connections, which considers information fiom the viewpoint of a personal history, remembered from the past and projected to the future. niis involves the integration of affect and cognition. The right fiontal lobe is critical at this highest level of consciousness. Other investigators have also stressed the importance of the fiontal lobe to personality and self-awareness. Damasio (1994) concluded that bilateral damage to prefiontal cortices, particularly involving the ventromedial sector caused impairnent of reasoning/decision making and emotiodfeeling, with the most severe consequences to the personaYsocia1 domain. Prigatano (1988, 1989) suggested that a disturbance in the integration of cognitive and affective information may cause disorders of self-awareness. He indicated that damage to brain regions including the prefrontal regions, impair the ability to integrate extrapersonal space with internal milieu and may explai.why patients with such injury often show major personality changes, as well as disturbed self-awareness. In hurnor, as ùi self-awareness, the integration of cognitive and affective infoxmation is cntical. Gardner et al. (1975) suggested that the realm of humor provides an appropriate domain to investigate an interplay between the cognitive and affective facets of an individual. He also indicated that, with few exceptions, these two facets of an individual following brain damage have been examined in complete independence of one another. In the present study, factor analysis of major variables ficm control participants fiom the hurnor appreciation and production tests produced two factors - Factor 1, representing humor detection and production, a cognitive dimension of humor, and Factor 2, representing humor appreciation, the af5ective dimension of humor. The results of the present study aiso indicated that patients with right frontal pathology exhibited a dissociation between their cognitive/verbal responses and their affectivehirth responses to humorous stimuli. Thus, a deficit in integrating cognitive with affective information in patients with fiontal lobe damage may underlie an impairment in the highest of hurnan functions, such as personaliv. self- awareness, and hurnor. As reviewed in the literature on fiontal lobe fiuictions, disturbance of personality and self-awareness are kequent sequelae of darnage to &ontal (particularly nJht frontal) regions, with a disorder of humor being a notable consequence of the personality change. The fionta1 lobe appears to be uniquely capable of performing the function of integration at the various levels descnbed above. This is based on its anatomical connections. A unique feature of the neural circuitry of the fiontal cortex as outlined by Nauta (1971; 1973) is its reciprocal relationship with two great functional realms, namely (1)parietaI and temporal regions of the cerebral cortex involved in the processing of visual, auditory, and somatic sensory information, and (2)the telencephalic limbic system and its subcortical correspondents, in particular, the hypothalamus and meso- and diencephalic structures associated with the hypothalamus. The reciprocal nature of both of these two relationships means that the fiontal lobe is a 'sensory' as well as an 'effector' mechanism. Further, the fiontal lobe is characterîzed distinctly by the greatest variety of cortic-limbic connections, and in particular, by its direct connections with the hypothalamus, making it a major neocortical representative of the limbic system. The reciprocity in the anatomical relationship suggests that the frontal cortex acts as both monitor and modulator of limbic rnechanisms. Nauta (1973) contends that by virtue of its anatomical relationships, the frontal cortex is involved in the re-representation of exteroceptive (information fiom the outside world) and interoceptive (information from the intemal miliedfeeling states). This provides a rationale for the social and affective role of the fiontal lobe. That is, the @ontal lobe firnctions as a 'sounding board' or 'intemal test-ground' enabling the perceiving of affective consequences of any particular action and pennitting a choice between alternatives of thought and action. This is compatible with some of the behavioral changes cornmonly associated with fionta1 lobe damage, such as flatness of affect, loss of ability to foresee the outcome of one's action, and socially inappropriate behavior (e.g., rnoria and witzelsucht discussed in the review). Thus, the frontal lobe is involved with integration of functions at the highest level. Pngatano (1988; 1989; 1991)' while discussing disorders of awareness following fiontal lobe darnage, accords a similar role to the £?ontal lobe, Le., the integration of thoughts and feelings. This is based on Mesulam's (1985) reconceptualization of hurnan brain structure in terms of the way they respond to different types of stimuli, in particular, the concepts of heteromodal cortex and paralimbic cortex. Mesularn suggested that the antenor tip of the temporal lobe is part of a "paralimbic belt", which is critical for interpreting the intemal milieu of the body. Adjacent to the paralimbic cortex is a region of the brain identified as the heteromodal cortex, which includes the regions of the brain that are last to develop phylogenetically and ontogenetically. This area responds to multiple stimuli and seems to interpret interna1 stimuli or sensations as well as purely external sensory input. The prekontal regions of the brain are heteromodal cortex and are in close proxirnity to the paralimbic belt. Prigatano (1988; 1989; 1991) suggests that the heteromodal cortex may provide the interface between perceptual information and thought processes and intemal perceptions called feeling states. It allows the individuai to integrate 'extrapersonal space' with the 'intemal milieu'. Disorders of the heteromodal cortex, including the frontal lobe, rnay cause impairment of the integration of cognitive with affective information, leading to disturbances in personality and in the highest cerebral function, namely self- awareness. These ideas have received Mersupport. Barbas (1995), reviewing the structural and anatomic relationships of the preftontal cortex indicated that this region provides the anatomic basis of cognitive-emotional interactions. This is based on the recognition that posterior basal and media1 parts of the prefkontal cortex belong to the cortical component of the limbic system. In addition, these prefrontal Iimbic areas @articularly the postenor orbitofiontal region) are multimodal, being widely interconnected with sensory areas (olfaction, vision, audition, and somatic sensation), as well as, receiving robust projections fkom limbic, poiymodal, and premotor cortices. The posterior orbitofkontal cortex iç also implicated in autonomie responses. As the recipient of input fiom both exteroceptive and interoceptive modalities, this region is in a position to integrate multiple aspects of the environment. The prefrontal cortex also receives subcortical influences, mainly inputs fkom the thaiamus and the amygdala. The co~ectional patterns of the prefiontal cortex suggest that sensory input the to region is highly integrated with input fbm cortices associated with mnemonic and emotional processes. The postenor orbitofionta1 region is particularly suited for integration, since it receives information about all aspects of the extemal and intemal environment, fkom thalamic nuclei involved in associative aspects of memory, and from the amygdala which may enrich events with an emotional component. Thus. the recognition that some prefrontal areas are limbic suggests that the prefi-ontal cortex not only serves as an integrative center for high-order co,gnitive processes, but is also involved in emotional processes, previously thought to be the exclusive domain of the cingulate cortex and a set of subcortical limbic structures. Recent information indicating that the limbic areas are progressive in evolution, as well as its strong connection with the association cortices, indicate that it is impossible to separate the cognitive from the emotional or mnernonic processes in the nervous system. While speaking of fiontal lobe damage and the functional deficits associated with such pathology, it is important to highlight its anatomical connections. As outlined above, an important feature of the fiontal lobe is its extensive reciprocal connections with other parts of the brain. In particular, the connections of the frontal lobe with the limbic system have been emphasized (Nauta, 1971 ; 1972; 1973). Therefore, behavioral deficits observed following fiontal lobe damage also reflect a disruption in the interrelation of the frontal region with other brain regions. In recent years, the fiontal systems, that is, the fkontal lobe and its connections, have been suggested as the anatomic bais of fkontal lobe functions (Stuss, et al., 1997). A disruption of the connections of the frontal lobe with the limbic system as a result of frontal lobe darnage may produce a deficit in humor since these connections are important in mediating the affective and motivational responses to the environment, as well as the ability to integrate infoxmation fiom the intemal milieu with environmental exteroceptive information (Nauta, 1971). Nauta (1973) indicated that the frontal lobe and the limbico-subcortical avis encompass neural mechanisms that allow man to be hurnan. The connections of the fiontal lobe with the amygdala may be especially important to humor. The amygdala, located in the inner or limbic portion of the temporal pole, has an important role in the association between stimuli and emotional response (Gloor, 1986; In Starkstein & Robinson, 1991). The fiontal lobe projects to and receives projections fi-om the arnygdala @arnasio, 1985). As reviewed by Ross (1997) the amygdala is responsible for endowing sensory information with affective and experiential tone. Through its connections with the hippocampal formation, the amygdala may influence the strength of consolidation of extrapersonal sensory information that will be stored in the neocortex as a fûnction of intrapersonal affective and experiential tone, and through its connections with the neocortex, rnay be responsible for the processing and storage of the affective and experiential tone as a distinct emotional-cognitive entity. Although the amygdala rnay be critical for engendering emotional and other experiential phenornena, it is also part of a complex neural network in which the neocortex probably serves as the repository for stoling expenential information in parallel and in registration with the extrapersonal sensory information of life events. The interactions between the temporal limbic system (including the amygdala) and the neocortex is important in the conscious experience of emotions in humans. That is, even though stimuli are processed by the amygdala, which is able to produce autonornic indicators of an emotional state, without neocortical elaboration the stimuli do not induce a conscious emotional experience or appropriate display behaviors (Ross, 1997). Kolb and Whishaw (1990) indicate that the close anatomical connections between the orbital prefiontal cortex and the amygdala, and the emotional changes following lesions to either region, suggest that these betong to some neural circuit regulating emotional behavior. In outlining the mechanism for emotional and behavioral distributions comprising the fiontal lobe syndrome, such as euphoria, disinhibition, and imtability, Starkstein and Robinson (1 99 1) highlighted the importance of frontal lobe connections with the arnygdala. They suggested that by means of the orbito-tempero-amygdala connections, cognitive functions may influence limbic activity, and a lesion in one of these regions may release the tonic inhibition exerted by the f?ontal lobe on the amygdala, which would resuit in emotional disinhibition. The loss of fronto-limbic connections may release emotions from intellectual control, producing a dissociation which results in manic syrnptomatology. Starkstein and Robinson (1991) fkther suggested that the limbic portions of the right hemisphere and the right fiontal region, is particularly relevant to the elation, grandiose delusions, and other symptorns of secondaxy mania. Since humor deficits are usually observed as part of a similar fiontal lobe syndrome, the disconnection of the fiontal lobe fiom the limbic system, particularly the amygdala, may be involved in producing a humor deficit. Thus, by virtue of the kontal lobe's extensive reciprocal anatomical connections, as well as by being heteromodal in function, the fiontal lobe provides the ideal substrate for integration at various levels of cognitive function. At the highest level, the frontal lobe is involved in the integration of cognitive with affective idonnation, thereby mediating the most complex and highest of integrated brain functions, including personality and self-awareness. Humor, requiring integration of Somation fiom different sources and at different levels, is related to these higher cognitive processes and to frontal lobe hction. This is supported by observations that a disorder of hurnor is a key feature of socially inappropriate behavior in fiontal lobe patients associated with irnpairments in penonality and self-awareness. As outlined above, fiontal lobe is important for the integration of function that is required for humor. There may be hemisphenc specialization for the type of integration that is necessary for humor, with the right hemisphere and the right fiontal region being more dominant. This is based on several observations from the literature, both in terms of the processing style of the right hemisphere and the kinds of information it handles. The characteristic processing style of the nght hemisphere rnay be important for integration of infoxmation. The right hemisphere is considered to be more adept at simultaneous processing of information, being more holistic and synthetic in handling al1 kinds of information (Springer & Deutsch, 1993). This ability to process information in a holistic and simultaneous manner is important in humor. McGhee (1983) suggested that, in humor appreciation, the right hemisphere is involved in producing sirnultaneous awareness of two rneanings (as in a pun) or of diverse elements that must be brought together in order to appreciate humor potentially present in a situation. Anatomical differences in neuronal organization have been suggested that may partially account for the different processing styles of the two hemispheres (McGhee, 1983). Gur et al. (1980), using radioisotope techniques, found a higher ratio of white matter to gray matter in the 5ght hemisphere than in the left. Since white matter consists prirnarily of rnyelinated fibers, they suggested that the spatial-gestaltmolistic functions of the right hemisphere are subserved by an organization that optirnizes transfer across regions. ui contrast, the proportion of gray matter was significantly greater in the left hemisphere. Gray matter consists of nerve cells and nonrnyelinated fibers, suggesting that verbal-analytic functions of the lefi hemisphere are subserved by an organization that emphasizes processing or transfer within regions. Further, the differences between the two hemispheres were particularly pronounced in the fiontal and precentral regions. These findings indicate that the right hemisphere and the right fiontal region in particular, is anatomically suited for holistic processing and to perform an integrative fùnction. The role of the fkontal lobe in episodic memory has also been lateralized. That is, the left and right prefrontal lobes are part of an extensive neuronal network that subserves episodic remembering, but the two prefrontal hemispheres play diflerent roles (Tulving, et al., 1994). According to their hemispheric encoding ! retrieval asymmetry (HERA) mode1 of prefrontal activation, the left prefiontal cortex is differenhally more involved with semantic retrieval and episodic encoding, whereas the right prefiontal cortex is more involved with episodic retrieval. i.e., retrieval of personal memones or past experience. Wheeler et al. (1997) indicated that the right prefrontal cortex may be a crucial area underlying the monitoring of complex, goal-directed activity, including recollection of the persona1 past. As indicated earlier, retrieval of knowledge and past experience is important to humor. Since this is preferentially the function of the nght fiontal lobe, this region would be important to perform the integration of humorous stimuli with information regarding past experience retrieved fkom episodic memory. In addition to the holistic and simultaneous processing style of the nght hemisphere, its role in retrieval of persona1 mernones (episodic memory), the type of information processed by the right hemisphere provides further support for hemisphenc specialization for humor. As indicated in the iiterature review, the right hemisphere is important for pragmatic and figurative language and for processing emotional stimuli. Pathology involving the nght hemisphere leads to personality and emotional changes, as well as an impairnent in humor. These functions within the right hemisphere have not been further localized. However, disturbances in pragmatic and narrative language, personality, and emotion similar to those reported in right hemisphere damaged patients are significant consequences of frontal lobe damage. A disorder of humor (e.g., moria and witzelsucht) is a key feature of personality and emotional disturbances reported in patients with right fiontal pathology. Similarly, disturbances in self-awareness are also lateralized and are related to nght prefiontal damage (Stuss, et al., 1997; Alexander, et al., 1979; Shiss, 199ta, b; Stuss et al. in press). Features which indicate an impairment in Ievels of awareness, for instance, extraordinary defusions and confabulations; denial; disturbance in the feeling of intimacy, irnmediacy, and warmth with regard to one's memory (a disturbance in episodic memory); as well as a dissociation between correct knowledge, use of howledge, or awareness of the implication of such knowledge have been observed by these investigators to be related to right fiontal pathology. Such observations in the right frontal patients suggest that language, persondity, and emotional changes in nght hemisphere patients may be localizable to nght fiontal pathology. Since the right hemisphere is specialized for processing emotions, the Bght fiontal region may be important for the integration of cognitive and dfective infoxmation that is the basis of these higher functions. The anatomical relationships and the heteromodal nature of the fiontal cortex indicate that it is well suited to perfom the integation required for mediating these hctions. Thus, many features of the right &ontal region - (a)anatomy, Le., greater interconnectedness of neurons and widespread anatomical connections; @)nature of brain region, Le., heteromodal cortex; (c)right hemisphere processing style, i-e., simultaneous or holistic processing; (d) its role in episodic memory retrieval and self-awareness, and (e)type of information processed, e.g., pragrnatic and figurative language and emotions - form the basis for its role in the integration of information required for humor. In terms of the specific region within the &ontal lobe that is rnost relevant to humor appreciation, the present study emphasized the role of the right frontal lobe, particularly the superior, anterior/polar region. This localization diverges fiorn Damasio's (1994) conclusions regarding the bilateral ventromedial sector as being the most relevant to deficits in the emotional and personaUsocia1 domains, as well as Barbas (1995) who indicated the postenor orbitofkontal region as being the most suited for integration of higher-order cognitive and emotional processes. Perhaps humor, in addition to the integration of cognitive and affective processes, is applicable to subtle aspects of personality and the relationship of self-awareiess to personality. Consistent with recent conceptions regarding the fiactionation of fiontal lobe fûnctions (Stuss, et al. 1995; Stuss, et al. in press), hurnor, a fiontal lobe function, also involves several interacting processes such as language, working memory, mental shifting, abstraction, and focused attention. The role of the fiontal lobe is in an executive or supervisory capacity, providing control of these functions and perforrning the integration of Somation fiom diverse sources. At the highest level, the integration of cognitive with affective information is critical to humor. For reasons presented above, the nght fkontal region provides the anatornic basis for the interaction and integration of the multiple processes involved in humor. This specialization for integration of the right frontal region makes it the ideal substrate for mediating higher cognitive functions such as personality, self-awareness, and humor. References

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Instructions: "1 am going to show you some cards one by one. On each card is a sign. These are signs in English that were found in countries around the world, written by people whose first language is not English and who are not quite familiar with English idioms. As a result, some of the signs tum out to be quite amusing. Rate each of the following signs on this 5-point scale according to how funny you think it is: Rate it a 5, if you think the sign is extremely funny; 4, if you find it very funny; 3 for quite fiinny; 2 for slightly funny; and 1 if you think it is not funny."

Test Items: 1. In a Bucharest hotel: The lift is being fixed for the next day. During that time we regret that you will be unbearable.

2. In a Rhodes tailor shop: Order your summers suit. Because is big rush we will execute customers in strict rotation.

3. Ln a restaurant in Paris: Lunch will be served to patrons between noon and 3 p.m.

4. In a Moscow hotel: You are welcome to visit the cemetery where famous Soviet composers, artists, and writers are buried daily except Thursday.

5. On a Polish hotel menu: Salad a h'sown make; limpid red beet soup with cheesy dumphgs in the form of a finger; roasted duck let loose; beef rashers beaten up in the country people's fashion. 6. In a Bangkok cleaners: Drop yow trousers here for best results.

7. At a Peking dry cleaners: Leave your dirty clothes here for best results and pick up same day.

8. A Hong Kong dentists ad: Teeth extracted by the latest Methodists.

9. In the lounge at a Berlin hotel: We request that al1 patrons check their belongings before leaving the lounge. The management is not responsible for any items lost or left behind.

10. In a Leipzig elevator: Do not enter the Lifi backwards, and only when lit up.

11. In an Athens hotel: Visitors are expected to cornplain at the office between the hours of 9 and 1 1 a.m. daily.

12. Ootside a Hong Kong tailor shop: Ladies may have a fit upstairs.

13. In a Belgrade hotel elevator: To rnove the cabin, push button for wishing floor. If the cabin should enter more persons, each one should press a number of wishing floor. Dnving is then going alphabetically by national order.

14. In a Bangkok temple: It is forbidden to enter a woman even a foreigner if dressed as a man. 15. Notice in a Moscow hotel: Please turn off lights and heat when you are not in your rooms to Save energy.

16. In a Yugosiav hotek The flatterhg of underwear with pleasure is the job of the chambermaid.

17. A sign in Germany's Black Forest: It is strictiy forbidden on our Black Forest camping site that people of different sex, for instance, men and women, live together in one tent unless they are married with each other for that purpose.

18. At a department store in Geneva: This store is monitored by surveillance cameras. The store policy is to prosecute al1 shoplifters.

2 9. In a Japanese hotel: You are invited to take advantage of the chambernaid.

20. In a Swiss Inn: Specid today - no ice crearn.

2 1. In the Amsterdam airport: The baggage check-in service will be closed daily between 12 midnight and 6 a.m.

22. In a Tokyo bar: Special cocktails for the ladies with nuts. 23. In a Zurich hotel: Because of the impropriety of entertaining guests of the opposite sex in the bedroom, it is suggested that the lobby be used for this purpose.

24. In a Tokyo hotel: 1s forbidden to steal hotel towels please. If you are not a person to do such a things please do not read notis.

25. Thai donkey-ride ad:

Would you like to ride your own ass?

26. In a Norwegian cocktail loung: Ladies are requested not to have children in the bar.

27. At a Gennan bank: Please wait in line here for the next available telier to serve you.

28. On a Moscow hotel room door: If this is your fist visit to the USSR you are welcome to it. Jokes and Storv Completion Test:

Instructions: Some jokes are presented below. Each of them will have the punchline, that is. the last line or hyending, left out. Following each joke 4 possible endings to the joke are also presented. Please pick the one you think is the correct, hyending.

Exam~le:A missionary was working with a tribe of cannibals. One day while he was waking down the street, he found a native staring at him intently. "Why do you look at me like that?" the missionary asked.

a. Then the cannibal cracked a raw egg on the missionary's head. b. The cannibal replied, "1 go to church every Sunday." c. The cannibal replied, "I've never seen a mksionary before." d. nie cannibal replie& "I'm the food inspecter."

Correct choice is d.

1. A tenant had not paid his room rent for several weeks. Tomorrow was his last chance to pay his rent before the landlord kicked him out. "See here" the landlord said "1'11 meet you half way. I'm ready to forget half of what you owe me." a.The tenant replied, "Half the city is under rent control." b.Then the tenant pants fell down and his plaid boxer shorts were exposed. c.The tenant replied, "Great, 1'11 meet you; I'11 forget the other half " d.The tenant replied, "Thank you, 1 can certainly pay half."

2. A man was on his first flight leamhg how to skydive. As he nervously got ready for his first jump, he said to his instructor, "1 packed the parachute myself, but Irm sure it won? open." a.And the instructor sees a mouse and jumps out of the plane without a parachute. b.And the instructor says, "In my opinion, you are jumping to a hasty conclusion." c.hd the instructor çays, "Donlt worry, you have a second parachute in case of emergency. Everything will be fine". d.hd the instructor says, "1 used to fly this type of aircraft during the war."

3. A woman wants to cook a rabbit stew. The hares hanging at the butcher's are quite large, however, so she asks the butcher, "I'd like to make some rabbit stew, but these things are too big. Could you cut one in two for me?' a.And the butcher takes a pie and throws it in her face. b.And the butcher says, "Sorry, Ma'rn, we don't spiit hares here." c.hd the butcher answers, "Certainly, would you like this rabbit?" d.And the butcher answers, "The price of veal has gone up recently." 4. A man went up to a lady in a crowded square. "Excuse me" he said. "Do you happen to have seen a policeman anywhere around here?" "I'm sorry" the woman answered "but I haven't seen a sign of one." Then the man said:

a."All of the wheels fell off of my car." b."All right, hurry up and give me your watch and pocketbook then." c."Damn, I've been looking for a half hour and can't hdone." d."My uncle is a cop."

5. A puy is in a bar mgto pick up a girl. Mer they have talked for a while, he asks her for her phone number. "It's in the book"', she says. "Fine", he answers "what's your name?" a-"This is my favourite bar", she repiies. b-Slipping on a banana peel, he split his pants. c."Thatls in the book too", she answers. d."Barbara Johnson. Can you remernber ihat?" she answers.

6. A ship is cruising in the Caribbean. One day a girl falls overboard and her father screarns: "1'11 give half my fortune to Save her." A fellow humps in and saves the girl. The father says, "1'11 keep my promise. Here's half my fortune." a.Then the fellow tips his hat to the girl and his toupee slips off. b.The fellow answers, "1 dontt want money; al1 I want to know is who shoved me." c.The fellow answers, "Th& you. 1need the money." d.The fellow says, "1 usualIy get seasick on boats."

7. Mr-Miller and MiWilson were at the auto show and began to talk about their children. Petting a shiny new car on the fender, Mi.Miller said, "Your son drives Iike lightning, doesn't he?" a.And Mr.Wilson answered "He's always striking trees." b.And Mr.Wi1son answered, "Fm afiaid to lend him our car." c.And Mr. Wilson answered, "I'm considering buying this car." d.Then Mr. Wilson cracked a raw egg on Mr.Millds head.

8. A parade was going down the street and two cousins were watching on the balcony. One said to the other: "Here cornes the parade and Aunt Helen will miss it." "Shels upstairs waving her hair" answered the other. The fmt said: a."Thatfstoo bad. She's been looking forward to this parade.'' b."AuntHelen used to be a member of a marching band.'' c."I wonder how she'll like the strawberry chewing gurn 1put in her curlers." d."Gee, can't we afford a flag?"

9. The neighbourhood borrower approached Mr.Smith sunday noon and inquired "Say Smith, are you using your lawnmower this aftemoon?" "Yes 1 am" Smith replied warily. T'en the neighbourhood borrower answered:

a."OOPS!" as the rake he walked on barely missed his face. b."Fine, then you won't be wanting your golf clubs, I'll just borrow them." c."Oh well, cm 1borrow it when you're done, then?" d."The birds are always eating my grass seed."

10. A new housekeeper was accused of helping herself to her master's liquor. She told him. "1'11 have you know sir, 1 come from honest English parents."

a.He said, "I'm not concemed with your English parents. What's worrying me is your scotch extraction." b.He said, "Al1 the same, the next time the liquor disappears, youlre fired." c.He said, "My favourite drink is a dry martini." d.Then the housekeeper saw a mouse and jumped into her master's lap.

11. A businessrnan is riding the subway after a hard day at the office. A young man sits down next to him and says, "Cal1 me a doctor .... cal1 me a doctor." The businessrnan asks, "What's the matter, are you sick?"

a.The other ançwers, "1 just graduated fiom medical school." b.The young man says, "Yes 1feel a littie weak. Please help me." c.The young man says, "My sister is a nurse." d.The young man pulls out a watergun and squirts the businessman.

12. A woman is taking her shower. Al1 of a sudden, her doorbell rings. She yells "Who's there?" and a man answers "Blind man". Well, she's a charitable lady so she nins out of the shower naked and opens the door. a.The man says, "Cm you spare a little change for a blind man?" b.The man says, "My seeing eye dog is ten years old." c.Then the blind man throws a pie in the woman's face. d.The man says, "Where should 1put these blinds, lady?"

13. An old tirner, looking tired, hobbled up to the bar. "What's the matter?" asked another regular "you look pretty bad." "It's yoorz" moaned the old tirne;, "Yve got a bad case of yoon." "What's yoorz?" asked the puzzled friend. a."It means I'm feeling down and 1need a strong drink." b."Bartender, will you tum on the television please?" c.And he pulls out the stool fiom under a startled drunk. d."Mine will be a double scotch on the rocks, thanks." 14. Two ants found themselves on top of a cracker box. They were ninning across it at a great rate. "Why are we ninning so fast?" asked one. Don't you see" said the other one, a."Crackers are my favourite food." b.Then the two ants j~mpin a man's pants. c."It says, 'tear across the dotted line."' d."It is aimost night, we should get home quickiy."

15. A man walks into a store and says to the cierk: "This is my wifels birthday. I'd like to buy her a fountain pen." The clerk winks at the man and says "You want to surprise her, huh?" And the husband answers: a."OUCH! 1got ants in my pants." b."Yes, she's expecting a cadîllac." c."Yes, and I think she'll like this present." d.llMy wife is four years older than I am."

16. Mable walked hto a pastry shop. After surveying al1 the pastries, she decided on a chocolate pie. "1'11 take that one" Mable said to the attendant, "the whole thing." "Shall 1 cut into four or eight pieces?" the attendant asked. a.Mable said, "Four pieces, please. I1mon a diet." b."Well, there are £ive people for dessert tonight, so eight pieces will be about nght." c.Mable said, "You make the most delicious sweet rolls in town." d.Then the attendant squirted whipped cream in Mable's face.

S tories

Instructions: The following are short stories describing a situation in real life. At the end of each you are given three possible endings to the story. Yoü pick the one that has the same main -idea as the rest of the story - the one that completes the story in a logical way.

Example: An elderly wornan was taking a train ride to Chicago. As the train pulled into the station, the porter knocked on her cornpartment door. "Chicago!" he amounced. "Shall I brush you off, Madam?" The woman stood up. a."My brother is a train porter"' the woman said. b.Just then she slipped on a banana peel. c."No," she said, "1 actually don? get off until the next s stop."

Correct choice is c. 1. A woman wants to cook a rabbit stew. The hares hanging at the butcher's are quite large. however, so she asks the butcher, "I'd like to make some rabbit stew, but these things are too big Could you cut one in two for me?'

a.And the butcher takes a pie and throws it in her face. b.And the butcher answers, "Certainly, would you like this rabbit?" cAnd the butcher answers, "the pnce of veal has gone up recently."

2. A man went up to a lady in a crowded square. "Excuse me" he said. "Do you happen to have seen a policeman anywhere around here?" "I'm sorry" the woman answered "but 1 havent seen a sign of one." Then the man said:

a."Damn, I've been looking for a half hour and can't find one." b."My uncle is a cop." c."All of the wheels fell off of my car."

3. A pyis in a bar trying to pick up a girl. After they have talked for a while, he asks her for her phone nurnber. "It's in the book1", she says. "Fine", he answers "what's your name?"

aSlipping on a banana peel, he split his pants. b."This is my favourite bar", she replies. c."Barbara Johnson. Cm you remember that?" she answers.

4. A ship is cruising in the Caribbean. One day a girl fdls overboard and her father screams: "1'11 give half my fortune to Save her." A fellow humps in and saves the girl. The father says, "1'11 keep my promise. Here's half my fortune."

a.Then the fellow tips his hat to the girl and his toupee slips ofE b.The fellow answers, "Thank you. 1 need the rnoney." c.The fellow says, "1 usually get seasick on boats."

5. Mr.Miller and MiWilson were at the auto show and began to talk about their children. Petting a shiny new car on the fender, Mr.Miller said, "your son drives like lightning, doesn't he?" a.And Mr. Wilson answered, "I'm afkaid to lend bua our car." b-And Mr.Wi1son answered, "I'm considering buying this car." c.Then Mr.Wilson cracked a raw egg on Mr.Millerls head.

6. A parade was going down the street and two cousins were watching on the baicony. One said to the other: "Here cornes the parade and Aunt Helen will miss it." "She's upstairs waving her haïr" answered the other. The first said: a."Aunt Helen used to be a member of a marching band." b."I wonder how she'll like the strawberry chewing gurn 1 put in her curlers." c."Thatfstoo bad. She's been looking forward to this parade." 7. A man walks into a store and says to the clerk: "This is my wife's birthday. I'd like to buy her a fountain pen." The clerk winks at the man and says "You want to surprise her, huh?" And the husband answers: a."My wife is four years older than I am." b."OUCH! I got ants in my pants." c."Yes,and 1 think she'll like this present."

8. Mable walked into a pastry shop. After surveying a11 the pastries, she decided on a chocolate pie. "F11 take that one" Mable said to the attendant, "the whole thing." "Shall 1 cut into four or eight pieces?" the attendant asked. a.Then the attendant squirted whipped cream in Mable's face. b.And Mable responded, "Well, there are five people for dessert tonight, so eight pieces will be about right." c.Mable said, "You make the most delicious sweet rolls in town."

9. An old timer, looking tired, hobbled up to the bar. "What's the matter?" asked another replar "you look pretty bad." "It's yoorz" moaned the old timer, "I've got a bad case of yoorz." "What's yoorz?" asked the puzzled fkiend. a. "Tt means I'm feeling down and 1need a strong drink." b.And he pulls out the stool from under a startled drunk. c."Bartender, will you turn on the television please?"

10. Two ants found themselves on top of a cracker box. They were running across it at a great rate. "Why are we running so fast?" asked one. Don't you see" said the other one, a.Then the two ants jump in a man's pants. b."It is almost night, we should get home quickly." c."Crackers are my favourite food."

11. The neighbourhood borrower approached Mr.Srnith sunday noon and inquired "Say Smith, are you using your lawnmower this afternoon?" "Yes 1 am" Smith replied warily. Then the neighbourhood borrower answered: a."Oh well, cm 1borrow it when you're done, then?" b."The birds are always eating my gras seed." c."OOPS!ll as the rake he walked on barely missed his face.

12. A new housekeeper was accused of helping herself to her master's liquor. She told him, "1'11 have you how sir, 1 corne fkom honest English parents." a.He said, "My favourite drink is a dry aartini." b.Then the housekeeper saw a mouse and jumped into her master's lap. c.He said, "Al1 the sarne, the next tirne the liquor disappears, you're fired." 13. A tenant had not paid his room rent for several weeks. Tomorrow was his fast chance to pay his rent before the Iandlord kicked him out. "See here" the landlord said "I'11 meet you half way. I'm ready to forget half of what you owe me." a.Then the tenant pants fell down and his plaid boxer shorts were exposed. b.The tenant replied, "Thank you, 1cm certainly pay half." c.The tenant replied, "Half the city is under rent control."

14. A man was on his first flight leaming how to skydive. As he nervously got ready for his first jump, he said to his instructor, "1 packed the parachute myself, but i'm sure it won? open." a.And the instnictor says, "Don't wony, you have a second parachute in case of emergency. Everything will be fine." b.And the instnictor says, "1 used to fly this type of aircrafl during the war." c.And the instmctor sees a mouse and jumps out of the plane without a parachute.

15. A businessman is nding the subway after a hard day at the office. A young man sits down next to him and says, "Cal1 me a doctor .... cal1 me a doctor." The businessman asks, "What's the matter, are you sick?" a.The young man says, "My sister is a nurse." b.The young man pulls out a watergun and squirts the businessman. c.The young man says, "Yes 1 feel a little weak. Please help me."

16. A woman is taking her shower. Al1 of a sudden, her doorbell rings. She yells "Who's there?" and a man answers "Blind man". Well, she's a charitable lady so she nuis out of the shower naked and opens the door. a.Then the blind man throws a pie in the woman's face. b.The man says, "Cmyou spare a little change for a blind man?" c.The man says, "My seeing eye dog is ten years old."