CHAPTER 17 Consciousness in Hypnosis

John F. Kihlstrom

Abstract correlates of hypnotic suggestion revealed by brain imaging. In hypnosis, subjects respond to suggestions for imaginative experiences that can involve alterations in conscious perception, mem­ ory, and action. However, these phenom­ Consciousness in Hypnosis ena occur most profoundly in those subjects who are highly hypnotizable. The chap­ Hypnosis is a process in which one per­ ter reviews a number of these phenomena, son (commonly designated the subject) including posthypnotic amnesia; hypnotic responds to suggestions given by another analgesia; hypnotic deafness, blindness, and person (designated the hypnotist) for imag­ agnosia; and emotional numbing, with inative experiences involving alterations in an eye toward uncovering dissociations perception, memory, and the voluntary con­ between explicit and implicit memory, per­ trol of action. Hypnotized subjects can be ception, and emotion. These dissociative oblivious to pain; they hear voices that aren't phenomena of hypnosis bear a phenotypic there and fail to see objects that are clearly similarity to the "hysterical" symptoms char­ in their field of vision; they are unable to acteristic of the dissociative and conversion remember the things that happened to them disorders. The experience of involuntariness while they were hypnotized; and they carry in hypnotic response is considered in light of out suggestions after hypnosis has been ter­ the concept of automatic processing. Hyp­ minated, without being aware of what they nosis may be described as an altered state are doing or why. In the classic case, these of consciousness based on the convergence experiences are associated with a degree of of four variables: induction procedure, sub­ subjective conviction bordering on delusion jective experience, overt behavior, and psy­ and an experience of involuntariness border­ chophysiological indices - including neural ing on compulsion.

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The Importance of Individual tizable subjects are compared to those who Differences are insusceptible to hypnosis. In any case, measurement of hypnotizability is crucial to hypnosis research: There is no point in The phenomena of hypnosis can be quite studying hypnosis in individuals who cannot dramatic, but they do not occur in every­ experience it. one. Individual differences in hypnotizabil­ Some clinical practitioners believe that ity are measured by standardized psycho­ virtually everyone can be hypnotized, if logical tests, such as the Harvard Group only the hypnotist takes the right approach, Scale of Hypnotic Susceptibility, Form A but there is little evidence favoring this (HGSHS:A) or the Stanford Hypnotic Sus­ point of view. Similarly, some researchers ceptibility Scale, Form C (SHSS:C). These believe that hypnotizability can be enhanced psychometric instruments are essentially by developing positive attitudes, motiva­ work samples ofhypnotic performance, con­ tions, and expectancies concerning hypnosis sisting of a standardized induction of hypno­ (Gorassini & Spanos, 1987 ), but there is also sis accompanied by a set of 12 representative evidence that such interventions are heavily hypnotic suggestions. For example, on both laced with compliance (Bates & Kraft, 1991). HGSHS:A and SHSS:C, subjects are asked As with any other skilled performance, hyp­ to hold out their left arm and hand, and then notic response is probably a matter of both it is suggested that there is a heavy object in aptitude and attitude: Negative attitudes, the hand, growing heavier and heavier, and motivations, and expectancies can interfere pushing the hand and arm down. The sub­ with performance, but positive ones are not ject's response to each suggestion is scored by themselves sufficient to create hypnotic according to objective behavioral criteria virtuosity. (for example, if the hand and arm lower Hypnotizability is not substantially corre­ at least 6 inches over a specified interval lated with most other individual differences of time), yielding a single score represent­ in ability or personality, such as intelligence ing his or her hypnotizability, or responsive­ or adjustment (Hilgard, 196 5). However, in ness to hypnotic suggestions. Hypnotizabil­ the early 196os, Ronald Shor (Shor, Orne, ity, so measured, yields a quasi-normal distri­ & O'Connell, 1962), Arvid As (As, 1962), bution of scores in which most people are at and others found that hypnotizability was least moderately responsive to hypnotic sug­ correlated with subjects' tendency to have gestions, relatively few people are refractory hypnosis-like experiences outside of formal to hypnosis, and relatively few fall within hypnotic settings, and an extensive interview the highest level of responsiveness (Hilgard, study by Josephine Hilgard (1970) showed 1965). that hypnotizable subjects displayed a high Although most people can experience level of imaginative involvement in such hypnosis to at least some d~gree, the most domains as reading and drama. In 1974, Tel­ dramatic phenomena of hypnosis - the ones legen and Atkinson developed a scale of that really count as reflecting alterations in absorption to measure the disposition to have consciousness are generally observed in subjective experiences characterized by the those "hypnotic virtuosos" who comprise the full engagement of attention (narrowed or upper 10 to 15% of the distribution of hyp­ expanded), and blurred boundaries between notizability. Accordingly, a great deal of hyp­ self and object (Tellegen & Atkinson, 1974). nosis research involves a priori selection of Episodes of absorption and related phenom­ highly hypnotizable subjects, to the exclu­ ena such as "flow" (Csikszentmihalyi, 1990; sion of those of low and moderate hypno­ Csikszentmihalyi & Csikszentmihalyi, 1988) tizability. An alternative is a mixed design are properly regarded as altered states of in which subjects stratified for hypnotizabil­ consciousness in their own right, but they ity are all exposed to the same experimental are not the same as hypnosis and so are not manipulations, and the responses of hypno- considered further in this chapter. CONSCIOUSNESS IN HYPNOSIS 447

Conventional personality inventories, ations in consciousness. The sensory alter­ such as the Minnesota Multiphasic Person­ ations exemplified by hypnotic analgesia ality Inventory and California Psychological or deafness, as well as posthypnotic amne­ Inventory, do not contain items related to sia, are disruptions in conscious awareness: absorption, which may explain their failure The subject seems to be unaware of per­ to correlate with hypnotizability (Hilgard, cepts and memories that ought to be acces­ 1965). However, absorption is not wholly sible to phenomenal awareness. Similarly, unrelated to other individual differences in posthypnotic suggestion, as well as the expe­ personality. Recent multivariate research rience of involuntariness that frequently I has revealed five major dimensions - the accompanies suggested hypnotic experi­ "Big Five" - which provide a convenient ences, reflects a loss of control over cognition summary of personality structure: neuroti­ and behavior. cism (emotional stability), extraversion, Despite these considerations, the status of agreeableness, conscientiousness, and open­ hypnosis as an altered state of consciousness ness to experience (John, 1990; Wiggins & has been controversial (e.g., Gauld, 1992; Trapnell, 1997 ). Absorption and hypnotiz­ Hilgard, 1971; Kallio & Revensuo, 2003; ability are correlated with those aspects of Kirsch & Lynn, 1995; Shor, 1979a).' For openness that relate to richness of fantasy example, psychoanalytically inclined theo­ life, aesthetic sensitivity, and awareness of rists classified hypnosis as an instance of inner feelings, but not those that relate to adaptive regression, or regression in the intellectance or sociopolitical liberalism service of the ego (Fromm, 1979; Gill & (Glisky & Kihlstrom, 1993; Glisky, Tataryn, Brenman, 1959). Orne believed that the Tobias, & Kihlstrom, 1991). essence of hypnosis was to be found in Absorption is the most reliable corre­ "trance logic" (Orne, 1959), whereas Hil­ late of hypnotizability; by contrast, vivid­ gard argued that the phenomena of hyp­ ness of mental imagery is essentially uncor­ nosis were essentially dissociative in nature related with hypnosis (Glisky, Tataryn, & (Hilgard, 1973 b, 1977 ). By contrast, Sarbin Kihlstrom, 1995). However, the statistical and Coe described hypnosis as a form of relations between hypnotizability and either role-enactment (Sarbin & Coe, 1972 ); Bar­ absorption or openness are simply too weak ber asserted that the phenomena of hyp­ to permit confident prediction of an indi­ nosis could be produced by anyone who vidual's actual response to hypnotic sug­ held appropriate attitudes, motivations, and gestion (Roche & McConkey, 1990 ). So expectancies (Barber, 1969). far as the measurement of hypnotizabil­ More recently, both Woody and Bowers ity is concerned, there is no substitute for (Woody & Bowers, 1994; Woody & Sadler, performance-based measures such as the 1998) and Kihlstrom (Kihlstrom, 1984, Stanford and Harvard scales. 1992a, 1998) embraced some version of Hilgard's neodissociation theory of divided consciousness. By contrast, the "sociocogni­ The Controversy over State tive" approach offered by Spanos (1986a, 1991) emphasized the motivated subject's Consciousness has two principal aspects: attempt to display behavior regarded as monitoring ourselves and our environment, characteristic of a hypnotized person and so that objects and events are accurately the features of the social context that represented in phenomenal awareness, and shaped these displays. Kirsch and Lynn controlling ourselves and the environment (Kirsch, 2001a,b; Kirsch & Lynn, 1998a,b) through the voluntary initiation and termi­ offered a "social cognitive" theory of hyp­ nation of thought and action (Kihlstrom, nosis that attributed hypnotic phenom­ 1984). From this point of view, the phe­ ena to the automatic effect of subjects' nomena that mark the domain of hypno­ response expectancies. Following Kuhn sis (Hilgard, 1973 a) seem to reflect alter- (1962), the "state" and "nonstate" views of THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS hypnosis have sometimes been construed wider sociocultural context. A truly ade­ as competing paradigms (e.g., Spanos & quate, comprehensive theory of hypnosis Chaves, 1970, 1991). will seek understanding in both cognitive and interpersonal terms. We do not yet have such a theory, but even if we did individ­ Consciousness and Social Influence ual investigators would naturally emphasize Part of the problem is the multifaceted one aspect, whether altered consciousness or nature of hypnosis itself Hypnosis entails social context, over the other in their work. changes in conscious perception, memory, The interindividual competition that is part and behavior, to be sure, but these changes and parcel of science as a social enterprise also occur following specific suggestions often leads investigators to write as if alter­ made by the hypnotist to the subject. As ations in consciousness and social influence White (1941) noted at the dawn of the mod­ were mutually exclusive processes - which ern era of hypnosis research, hypnosis is they simply are not. a state of altered consciousness that takes Taken together with the null-hypothesis place in a particular motivational context statistical tests that remain part and parcel the motivation being to behave like a hypno­ of the experimental method, and a propen­ tized subject. Orne (1959), who was White's sity for making strong rather than weak infer­ protege as both an undergraduate and a grad­ ences from experimental data, investigators uate student at Harvard, famously tried to will often present evidence for one process distinguish between artifact and essence of as evidence against the other. But if there hypnosis, but a careful reading of his work is one reason why hypnosis has fascinated makes it clear that the demand characteris­ successive generations of investigators, since tics that surround hypnosis are as important the very dawn of psychology as a science, it as any "trance logic" that arises in hypnosis. is that hypnosis exemplifies the marvelous Similarly, at the dawn of what might complexity of human experience, thought, be called the "golden age" of hypnosis and action. In hypnosis and elsewhere, com­ research, Sutcliffe published a pair of semi­ prehensive understanding will require a cre­ nal papers that contrasted a credulous view ative synthesis in the spirit of discovery, of hypnosis, which holds that the mental rather than the spirit of proof - a creative states instigated by suggestion are identical synthesis of both-and, as opposed to a stance to those that would be produced by the of either-or. actual stimulus state of affairs implied in the suggestions, with a skeptical view that Defining an Ahered State holds that the hypnotic subject is acting as if the world were as suggested (Sutcliffe, Part of the problem as well are the diffi­ 1960, 1961). This is, of course, a version culties of defining precisely what we mean of the familiar state-nonstate dichotomy, by an altered state of consciousness (Lud­ but Sutcliffe also offered a third view: that wig, 1966). Some theorists have argued that hypnosis involves a quasi-delusional alter­ every altered state should be associated with ation in self-awareness - an altered state a unique physiological signature, much as of consciousness that is constructed out of dreaming is associated with the absence of the interaction between the hypnotist's sug­ alpha activity in the EEG and the occur­ gestions and the subject's interpretation of rence of rapid eye movements (REM). The those suggestions. lack of a physiological indicator for hypno­ Thus, hypnosis is simultaneously a state sis, then, is taken as evidence that hypnosis of (sometimes) profound cognitive change, is not a special state of consciousness after involving basic mechanisms of perception, alL But of course, this puts the cart before memory, and thought, and a social interac­ the horse. Physiological indices are validated tion, in which hypnotist and subject come against self-reports: Aserinsky and Kleitman together for a specific purpose within a (1953) had to wake their subjects up during CONSCIOUSNESS IN HYPNOSIS 449 periods of REM and ask them if they were hypnotizable subjects, even the induction dreaming. As such, physiological correlates procedure may be unnecessary. have no privileged status over introspective 2. Subjective Experience: Introspective self­ self-reports: Aserinsky and Kleitman were reports of changes in subjective experi­ in no position to contradict subjects who ence would seem to be central to any said "no." It is nice when our altered states altered state of consciousness. As noted have distinct physiological correlates, but earlier, the domain of hypnosis is defined our present knowledge of mind-body rela­ by changes in perception, memory, and tions is simply not sufficient to make such the voluntary control of behavior - anal­ correlates a necessary part of the definition. gesia, amnesia, the experience of involun­ After all, cognitive neuroscience has made tariness, and the like. If the hypnotist gives very little progress in the search for the a suggestion-for example, that there is an neural correlates of ordinary waking con­ object in the subject's outstretched hand, sciousness (Metzinger, 2000 ). How far in getting heavier and heavier - and the sub­ the future do the neural correlates of altered ject experiences nothing of the sort, it states of consciousness, like hypnosis, await? is hard to say that he or she has been In the final analysis, it may be best to treat hypnotized. hypnosis and other altered states of con­ 3 . Overt Behavior: Of course, a reliance on sciousness as natural concepts, represented self-reports has always made psycholo­ by a prototype or one or more exem­ gists nervous, so another residue of radi­ plars, each consisting of features that are cal behaviorism (the first was the reliance only probabilistically associated with cate­ on operational definitions) is a focus on gory membership, with no clear boundaries overt behavior. If a subject hallucinates between one altered state and another, or an object in his outstretched hand, and between altered and normal consciousness feels it grow heavier and heavier, eventu­ (Kihlstrom, 1984). And because we can­ ally his arm ought to drop down to his not have direct knowledge of other minds, side. As noted earlier, individual differ­ altered states of consciousness must also ences in hypnotizability are measured in remain hypothetical constructs, inferred from terms of the subject's publicly observable, a network of relations among variables that overt, behavioral response to suggestions. are directly observable (Campbell & Fiske, But in this instance, the overt behavior is, 1959; Gamer, Hake, & Eriksen, 1956; Stoyva to borrow a phrase from the Book of Com­ & Karniya, 1968), much in the manner of mon Prayer, an outward and visible sign of a psychiatric diagnosis. From this point of an inward and spiritual grace: It is a con­ view the diagnosis of an altered state of con­ sequence of the subject's altered subjec­ sciousness can be made with confidence to tive experience. Behavioral response is of the extent that there is convergence among no interest in the absence of correspond­ four kinds of variables: ing subjective experience. For this rea­ 1. Induction Procedure: Operationally, a spe­ son, requests for "honesty reports" (Bow­ cial state of consciousness can be defined, ers, 1967; Spanos & Barber, 1968) or other in part, by the means employed to induce appropriate postexperimental interviews it- or, alternatively, as the output result­ (Orne, 1971; Sheehan &McConkey,1982) ing from a particular input. Barber (1969) can help clarify subjects' overt behavior employed such an input-output defini­ and serve as correctives for simple behav­ tion as the sole index of hypnosis, largely ioral compliance. ignoring individual differences in hyp­ 4· Psychophysiological Indices: Because both notizability. At the very least, hypnosis self-reports and overt behaviors are under would seem to require both a hypnotic voluntary control, and thus subject to dis­ induction and a hypnotizable individual tortion by social-influence processes, hyp­ to receive it. But in the case of very highly nosis researchers have been interested in THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS

psychophysiological indices of response affecting tactile sensitivity, "special senses" including, of course, various brain imag­ such as vision and audition, and motor func­ ing techniques. Over the years, a number tion. Charcot held that these symptoms, of such indices have been offered, includ­ in tum, were the products of "functional" ing skin conductance and alpha activ­ lesions in the nervous system produced by ity, but these have usually proved to emotional arousal and suggestion. be artifacts of relaxation and not intrin­ Charcot's interest in hysteria passed to sic to hypnosis. In retrospect, it was his protege Pierre Janet, who ·held that probably a mistake to expect that there the fundamental difficulty in hysteria was would be any physiological correlates of a restriction in awareness - such that, for hypnosis in general, following an induc­ example, hysterically deaf patients were not tion procedure but in the absence of aware of their ability to hear and hysteri­ any specific suggestions (Maquet et al., cally paralyzed patients were not aware of 1999 ), because subjects can have a wide their ability to move (Janet, 1907 ). Like variety of experiences while they were Charcot, Janet was particularly impressed by hypnotized. Progress on this issue is the apparently paradoxical behavior of hys­ more likely to occur when investiga­ terical patients, as exemplified by ostensibly tors focus on the physiological correlates blind individuals who nevertheless displayed of specific hypnotic suggestions - as in visually guided behavior. Janet argued that brain imaging work that shows specific these behaviors were mediated by mental changes in brain activity corresponding to structures called psychological automatisms. hypnotic visual hallucinations (Kosslyn, In his view, these complex responses to Thompson, Costantini-Ferrando, Alpert, environmental events were normally acces­ & Spiegel, 2ooo) or analgesia (Rainville, sible to conscious awareness and control, Hofbauer, Bushnell, Duncan, & Price, but had been "split off' from the normal 2002). stream of conscious mental activity by trau­ matic stress a situation that Janet called desaggregation, or, in English translation, Hypnosis and Hysteria "dissociation." At least since the late 19th century, interest Although the hegemony of Freudian psy­ in hypnosis has had its roots in the med­ choanalysis in psychiatry during the first half ical and psychiatric phenomenon known of the 2oth century led to a decline of inter­ as hysteria (for historical overviews and est in the classical syndromes of hysteria, detailed references, see Kihlstrom, 1994a; the syndrome as such was listed in the early Veith, 1965). This term originated some (1952 and 1968) editions of the Diagnos­ 4,ooo years ago in ancient Egyptian (and tic and Statistical Manual for Mental Dis­ later Greek) medicine to refer to a variety of orders (DSM) published by the American diseases thought to be caused by the migra­ Psychiatric Association. Beginning in 198o, tion of the uterus to various parts of the more recent versions of DSM dropped the body. In the 17th century, the English physi­ category "hysteria" in favor of separate list­ cian Thomas Sydenham reformulated the ings of dissociative disorders- including psy­ diagnosis so that hysteria referred to physi­ chogenic amnesia and multiple personal­ cal symptoms produced by non-organic fac­ ity disorder - and conversion disorder, listed tors. In the 19th century, the concept of hys­ under the broader rubric of the somata­ teria was refined still further, by Briquet, a form disorders (Kihlstrom, 1992b, 1994a). French neurologist, to include patients with As the official psychiatric nosology is cur­ multiple, chronic physical complaints with rently constituted, only the functional dis­ no obvious organic basis (Briquet, 1859). orders of memory (Kihlstrom & Schac­ Sometime later, Charcot noticed that the ter, 2ooo; Schacter & Kihlstrom, 1989) are symptoms of hysteria mimicked those of cer­ explicitly labeled as dissociative in nature. tain neurological illnesses, especially those However, it is clear that the conversion CONSCIOUSNESS IN HYPNOSIS

disorders also involve disruptions in con­ Dissociative Phenomena in Hypnosis scious awareness and control (Kihlstrom, 1992b, 1994a; 2oo1a; Kihlstrom & Schac­ As intriguing and historically important as ter, 2ooo; Kihlstrom, Tataryn, & Hoyt, 1993; the syndromes of hysteria and dissociation Schacter & Kihlstrom, 1989). Renewed are, it is also true that they are very rare interest in the syndromes of hysteria, recon­ and for that reason (among others) have strued in terms of dissociations affecting rarely been subject to controlled experi­ conscious awareness, was foreshadowed by mental investigation. However, beginning Hilgard's "neodissociative" theory of divided with Charcot's observation that hysterical l consciousness, which re-established the link patients are highly suggestible, a number of between hypnosis and hysteria (Hilgard, theorists have been impressed by the phe­ .. 1973 b, 1977; see also Kihlstrom, 1979, 1992a; notypic similarities between the symptoms Kihlstrom & McGlynn, 1991). of hysteria and the phenomena of hypno­ Viewed from a theoretical perspective sis. Accordingly, it has been suggested that .. centered on consciousness, the dissociative hypnosis might serve as a laboratory model disorders include a number of different syn­ for hysteria (Kihlstrom, 1979; Kihlstrom & dromes all involving disruptions in the mon­ McGlynn, 1991; see also Oakley, 1999). In itoring and/or controlling functions of con­ this way, study of alterations in conscious­ sciousness that are not attributable to brain ness in hypnosis might not just help us insult, injury, or disease (Kihlstrom, 1994a, understand hypnosis, but also hysteria and 2001a). These syndromes are reversible, the dissociative and conversion disorders as in the sense that it is possible for the well. In this regard, it is interesting to note patient to recover the lost functions. But that hypnotically suggested limb paralysis even during the symptomatic phase of seems to share neural correlates, as well as the illness, the patient will show evi­ surface features, with conversion hysteria dence of intact functioning in the affected (Halligan, Athwal, Oakley, & Frackowiak, system, outside awareness. Thus, patients 2ooo; Halligan, Oakley, Athwal, & Frack­ with psychogenic (dissociative) amnesia, owiak, 2ooo; Terao & Collinson, 2000). fugue, and multiple personality disorder may show impaired explicit memory but spared Implicit Memory in Posthypnotic Amnesia implicit memory (Kihlstrom, 2001a; Schac­ ter & Kihlstrom, 1989). In the same way, Perhaps the most salient alteration in con­ patients with conversion disorders affect­ sciousness observed in hypnosis is the one ing vision and hearing may show impaired that gave hypnosis its name: posthypnotic explicit perception but spared implicit amnesia. Upon termination of hypnosis, perception (Kihlstrom, 1992b; Kihlstrom, some subjects find themselves unable to Barnhardt, & Tataryn, 1992). In light of remember the events and experiences that these considerations, a more accurate tax­ transpired while they were hypnotized - an onomy of dissociative disorders (Kihlstrom, amnesia that is roughly analogous to that 1994a) would include three subcategories of experienced after awakening from sleep­ syndromes: ing. Posthypnotic amnesia does not occur in the absence of direct or implied suggestions 1. those affecting memory and identity (e.g., (Hilgard & Cooper, 1965), and the forgot­ functional amnesia, fugue, and multiple ten memories are not restored when hyp­ personality disorder); nosis is reinduced (Kihlstrom, Brenneman, 2. those affecting sensation and perception Pistole, & Shor, 198 5). Posthypnotic amnesia (e.g., functional blindness and deafness, is so named because the subject's memory analgesia, and tactile anesthesia); is tested in hypnosis, but hypnotic amnesia, 3. those affecting voluntary action (e.g., fun­ in which both the suggestion and the test ctional weakness or paralysis of the limbs, occur while the subject is hypnotized, has aphonia, and difficulty swallowing). the same properties. Although posthypnotic THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS amnesia typically covers events and experi­ various sorts of priming effects observed in ences that transpired during hypnosis, it is amnesic patients, is for all intents and pur­ also possible to suggest amnesia for events poses unconscious memory. that occurred while the subject was not Early evidence that posthypnotic amne­ hypnotized (Barnier, 1997; Bryant, Barnier, sia impaired explicit memory but spared Mallard, & Tibbits, 1999). Both features fur­ implicit memory came from a pair of exper­ ther distinguish posthypnotic amnesia from iments by K.ihlstrom (198o), which were state-dependent memory (Eich, 1988). in turn inspired by an earlier investiga­ In contrast to the amnesic syndrome asso­ tion by Williamsen and his colleagues (see ciated with hippocampal damage, posthyp­ also Barber & Calverley, 1966; Williamsen, notic amnesia is temporary: On administra­ Johnson, & Eriksen, 1965). Kihlstrom found tion of a prearranged cue, the amnesia is that hypnotizable subjects, given an amne­ reversed and the formerly amnesic subject is sia suggestion, were unable to recall the now able to remember the previously forgot­ items in a word list that they had mem­ ten events (K.ihlstrom & Evans, 1976; Nace, orized during hypnosis. However, they Orne, & Hammer, 197 4) although there is remained able to use these same items some evidence that a small residual amnesia as responses on free-association and cat­ may persist even after the reversibility cue egory instance-generation tasks. K.ihlstrom has been given (K.ihlstrom & Evans, 1977 ). originally interpreted this as reflecting a Reversibility marks posthypnotic amnesia as dissociation between episodic and seman­ a disruption of memory retrieval, as opposed tic memory as did Tulving (1983), who to encoding or storage, somewhat like the cited the experiment as one of four con­ temporary retrograde amnesias observed vincing demonstrations of the episodic­ in individuals who have suffered concus­ semantic distinction. However, Kihlstrom sive blows to the head (K.ihlstrom, 198 5; also noted a priming effect on the pro­ K.ihlstrom & Evans, 1979). The difference, duction of list items as free associations of course, is that posthypnotic amnesia is a and category instances, compared to con­ functional amnesia - an abnormal amount trol items that had not been learned; fur­ of forgetting that is attributable to psycho­ thermore, the level of priming observed logical factors, rather than to brain insult, was the same as that shown by insuscep­ injury, or disease (K.ihlstrom & Schacter, tible subjects who were not amnesic for :woo). In fact, as noted earlier, posthypnotic the word list. 2 amnesia has long been considered to be a Spared priming during posthypnotic laboratory model of the functional amne­ amnesia was subsequently confirmed by sias associated with hysteria and dissociation Spanos and his associates (Bertrand, Spanos, (Barnier, 2o02; Kihlstrom, 1979; K.ihlstrom & Radtke, 1990; Spanos, Radtke, & Dubreuil, & McGlynn, 1991). 1982), although they preferred to interpret Probably the most interesting psychologi­ the results in terms of the demands con­ cal research concerning posthypnotic amne­ veyed by test instructions rather than disso­ sia concerns dissociations between explicit ciations between explicit and implicit mem­ and implicit memory (Schacter, 1987 ), and ory. Later, Dorfman and K.ihlstrom (1994) posthypnotic amnesia is no exception. Fol­ bolstered the case for spared priming by cor­ lowing Schacter (1987 ), we can identify recting a methodological oversight in the explicit memory with conscious recollec­ earlier studies: The comparison of prim­ tion, as exemplified by performance on tra­ ing with free recall confounded explicit ditional tests of recall and recognition. By and implicit memory with the cue environ­ contrast, implicit memory refers to the influ­ ment of the memory test. The dissociation ence of some past event on current expe­ between explicit and implicit memory was rience, thought, and action in the absence confirmed when a free-association test of of (or independent of) conscious recollec­ priming was compared to a cued-recall test tion. Implicit memory, as exemplified by of explicit memory. Similarly, Barnier and CONSCIOUSNESS IN HYPNOSIS 453

her colleagues extended the dissociation to 1987 ). Interestingly, source amnesia was explicit and implicit memory for material first identified in the context of hypnosis learned outside as well as within hypnosis (Cooper, 1966; Evans, 1979a,b, 1988; Evans (Bamier, Bryant, & Briscoe, 2001). & Thome, 1966). Evans and Thome (1966) Whereas most studies of implicit mem­ found that some amnesic subjects retained ory in the amnesic syndrome employ tests world-knowledge that had been taught to of repetition priming, such as stem and frag­ them during hypnosis, (e.g., the color an ment completion, the studies just described amethyst turns when exposed to heat or employed tests of semantic priming, which the difference between the antennae of l cannot be mediated by a perceptual repre­ moths and butterflies), although they did sentation of the stimulus materials. How­ not remember the circumstances in which ever, David and his colleagues (David, they acquired this information. In a later Brown, Pojoga, & David, 2000) found study, Evans (1979a) showed that source that posthypnotic amnesia spared repetition amnesia did not occur in insusceptible sub­ priming on a stem-completion task. Simi­ jects who simulated hypnosis and posthyp­ lar results were obtained by Barnier et al. notic amnesia. Although the methodology of (zoot). In an especially important twist, Evans' study has been criticized (Coe, 1978; David et al. employed Jacoby's process dis­ Spanos, Gwynn, Della Malva, & Bertrand, sociation paradigm (Jacoby, 1991) to con­ 1988), most of these criticisms pertain to firm that the priming spared in posthypnotic the real-simulating comparison and do not amnesia is a reflection of involuntary uncon­ undermine the phenomenon itself Along scious memory, rather than either involun­ with the notion of demand characteris­ tary or voluntary conscious memory. 3 That is tics (Kihlstrom, 2002a; Orne, 1962, 1973), to say, the spared priming is a genuine reflec­ source amnesia is one of the most salient tion of implicit, or unconscious, memory. examples of a concept developed in hyp­ With the benefit of hindsight, we can nosis research that has become part of the trace studies of implicit memory in posthyp­ common parlance of psychological theory.+ notic amnesia at least as far as the clas­ Source amnesia might be interpreted as sic work of Hull (Hull, 193 3; Kihlstrom, a form of implicit learning (Berry & Dienes, zoo4a), who demonstrated that posthyp­ 1993; Reber, 1967,1993; Seger, 1994). In line notic amnesia impaired recall but had no with the traditional definition of learning, effect on practice effects, savings in relearn­ as a relatively permanent change in behav­ ing, or retroactive interference (see further ior that occurs as a result of experience, we discussion below). Hull concluded merely may define implicit learning as the acquisi­ that the forgetting observed in posthypnotic tion of new knowledge in the absence either amnesia was "by no means complete" (p. of conscious awareness of the learning expe­ 138) - much as Gregg (1979, 1982) later rience or conscious awareness of what has interpreted the evidence as reflecting the dis­ been learned, or both. Although evidence tinction dissociation between optional and for implicit learning can be construed as evi­ obligatory aspects of memory performance. dence for implicit memory as well (Schac­ But we can now interpret the same evidence ter, 1987 ), we may distinguish between the as illustrating a strong dissociation between two phenomena with respect to the sort explicit and implicit memory. of knowledge affected. In implicit mem­ In addition to priming, the dissocia­ ory, the memories in question are episodic tion between explicit and implicit mem­ in nature, representing more or less discrete ory is revealed by the phenomenon of episodes in the life of the learner. Mem­ source amnesia, in which the subject retains ories are acquired in implicit learning as knowledge acquired through some learn­ well, of course, but in this case we are con­ ing experience while forgetting the learn­ cerned with new semantic and procedural ing experience itself (Schacter, Harbluk, & knowledge acquired by the subject. When McClachlan, 1984; Shimamura & Squire, implicit and explicit learning are dissoci- 454 THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS

ated, subjects have no conscious access to the Implicit Perception in Hypnotic Analgesia knowledge - in which case implicit learning counts as a failure of metacognition (Flavell, In addition to their effects on memory, 1979; Metcalfe & Shimamura, 1994; Nelson, hypnotic suggestions can have very dra­ 1992,1996; Nelson & Narens, 1990; Reder, matic effects on the experience of pain 1996; Yzerbyt, Lories, & Dardenne, 1998). (Hilgard & Hilgard, 1975; Montgomery, Because the subjects in Evans' experiments DuHamel, & Redd, 2ooo). Although hyp­ were aware ofwhat they had learned, though notic analgesia was supplanted by more reli­ they were amnesic for the learning experi­ able chemical analgesia almost as soon as ence, source amnesia is better construed as its efficacy was documented in the mid- an example of implicit memory. 19th century, modern psychophysical stud­ Preserved priming on free-association and ies confirm that hypnotizable subjects given category-generation tasks, in the face of suggestions for analgesia can experience impaired recall, is a form of dissociation considerable relief from laboratory pain between explicit and implicit memory. Pre­ (Faymonville et al., 2ooo; Hilgard, 1969; served learning, in the face of amnesia for Knox, Morgan, & Hilgard, 1974). In fact, a the learning experience, is also a form of comparative study found that, among hyp­ dissociation between explicit and implicit notizable subjects, hypnotic analgesia was memory. But the case of posthypnotic amne­ superior not just to placebo but also to mor­ sia is different, in at least three respects, phine, diazepam, aspirin, acupuncture, and from other amnesias in which these disso­ biofeedback (Stern, Brown, Ulett, & Sletten, ciations are observed. First, in contrast to 1977). Although hypnosis can serve as the the typical explicit-implicit dissociation, the sole analgesic agent in surgery, it is proba­ items in question have been deeply pro­ bly used more appropriately as an adjunct cessed at the time of encoding. In the prim­ to chemical analgesics, where it has been ing studies, for example, the critical targets shown to be both effective and cost effec­ were not just presented for a single trial, tive in reducing actual clinical pain (Lang, but rather were deliberately memorized over Benotsch et al., 2ooo; Lang, Joyce, Spiegel, the course of several study-test cycles to a Hamilton, & Lee, 1996).5 strict criterion of learning (Dorfman & Hypnotic analgesia is not mediated by Kihlstrom, 1994; Kihlstrom, 1980 ). Second, relaxation, and the fact that it is not the priming that is preserved is semantic reversed by narcotic antagonists would seem priming, which relies on the formation dur­ to rule out a role for endogenous opiates ing encoding and preservation at retrieval (Barber & Mayer, 1977; Goldstein & Hil­ of a semantic link between cue and target. gard, 1975; Moret et al., 1991; Spiegel & This priming reflects deep, semantic process­ Albert, 1983). There is a placebo com­ ing of a sort that cannot be mediated by a ponent to all active analgesic agents, and perceptual representation system. Third, the hypnosis is no exception; however, hypno­ impairment in explicit memory is reversible: tizable subjects receive benefits from hyp­ Posthypnotic amnesia is the only case I know notic suggestion that outweigh what they where implicit memories can be restored to or their insusceptible counterparts achieve explicit recollection. from plausible placebos (McGlashan, Evans, Taken together, then, these priming & Orne, 1969; Stern et al., 1977 ). It has results reflect the unconscious influence of also been argued that hypnotized subjects semantic representations formed as a result employ such techniques as self-distraction, of extensive attentional activity at the time stress inoculation, cognitive reinterpreta­ of encoding. The priming itself may be an tion, and tension management to reduce automatic influence, but again it is not the pain (Nolan & Spanos, 1987; Spanos, 1986b). sort that is produced by automatic pro­ Although there is no doubt that cognitive cesses mediated by a perceptual represen­ strategies can reduce pain, their success, tation system. unlike the success of hypnotic suggestions, CONSCIOUSNESS IN HYPNOSIS 455

is not correlated with hypnotizability and istration that can be tapped by the hidden thus is unlikely to be responsible for the observer method. effects observed in hypnotizable subjects The paradox of hypnotic analgesia can (Hargadon, Bowers, & Woody, 1995; Miller also be viewed through an extension of & Bowers, 1986, 1993). the explicit-implicit distinction from learn­ Rather, Hilgard suggested that hypnotic ing and memory to perception (Kihlstrom, analgesia entails a division of consciousness 1996; Kihlstrom et al., 1992). Explicit per­ that prevents the perception of pain from ception refers to the conscious perception of being represented in conscious awareness a stimulus event, whereas implicit percep­ l (Hilgard, 1973b, 1977). In other words, ver­ tion refers to the effect of such an event on bal reports of pain and suffering reflect the the subject's ongoing experience, thought, conscious perception of pain, whereas phys­ and action in the absence of, or indepen­ iological responses reflect the processing of dent of, conscious awareness. Just as explicit pain processed outside of conscious aware­ and implicit memory can be dissociated in ness. Hilgard's "hidden observer" is both a the amnesic syndrome and in posthypnotic metaphor for the subconscious perception amnesia, so explicit and implicit perception of pain and a label for a method by which can be dissociated in "subliminal" percep­ this subconscious pain can be accessed tion (Marcel, 198 3) or prosopagnosia (Bauer, (Hilgard, Morgan, & Macdonald, 197 5; Knox 1984). In the case of hypnotic analgesia, et al., 1974). Although it has been suggested explicit perception of the pain stimulus is that hidden observer reports are artifacts reflected in subjects' self-reports of pain, of experimental demands (Spanos, 1983; whereas implicit perception is reflected in Spanos, Gwynn, & Starn, 1983; Spanos & their physiological responses to the pain Hewitt, 1980 ), Hilgard showed that both the stimulus. overt and covert pain reports of hypnotized subjects differed from those given by sub­ Implicit Perception in Hypnotic Deafness jects who are simulating hypnosis (Hilgard, Hilgard, Macdonald, Morgan, & Johnson, Dissociations between explicit and implicit 1978; Hilgard, Macdonald, Morgan, & John­ perception can also be observed in two I ~ son, 1978; see also Laurence, Perry, & other classes of hypnotic phenomena. In Kihlstrom, 1983). hypnotic esthesia, the subject experiences a The division in consciousness in hypnotic marked reduction in sensory acuity: Exam­ analgesia, as proposed by Hilgard, would ples include hypnotic deafness, blindness, help explain one of the paradoxes of hyp­ and tactile anesthesia. In hypnotic negative notic analgesia, which is that it alters sub­ hallucinations, the subject fails to perceive jects' self-reports of pain but has little or no a particular object (or class of objects) in the effect on reflexive, physiological responses environment, but otherwise retains normal to the pain stimulus (e.g., Hilgard & Morgan, levels of sensory function (hypnotized sub­ 1975; Hilgard et al., 1974). One interpreta­ jects can experience positive hallucinations tion of this difference is that hypnotized sub­ as well, perceiving objects that are not actu­ jects consciously feel the pain after all. How­ ally present in their sensory fields). Although ever, we know on independent grounds that the hypnotic esthesias mimic sensory disor­ physiological measures are relatively unsatis­ ders, the content-specificity of the negative factory indices of the subjective experience hallucinations marks them as more percep­ of pain (Hilgard, 1969). From the perspec­ tual in nature. tive of neodissociation theory, the dimin­ Careful psychophysical studies, employ­ ished self-ratings are accurate reflections of ing both magnitude-estimation (Crawford, the subjects' conscious experience of pain, Macdonald, & Hilgard, 1979) and signal­ whereas the physiological measures show detection (Graham & Schwarz, 1973) that the pain stimulus has been registered paradigms, have documented the loss and processed outside of awareness - a reg- of auditory acuity in hypnotic deafness. THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS

Nevertheless, as is the case in posthyp­ subjects would select, from a visually pre­ notic amnesia and hypnotic analgesia, sub­ sented array, words that were phonetically jects experiencing these phenomena show (but not semantically) similar to words that through their behavior that stimuli in the tar­ had been spoken to them (Nash, Lynn, Stan­ geted modality continue to be processed, if ley, & Carlson, 1987 ). Because the hypnotic outside of awareness. For example, Hilgard's subjects selected fewer such words compared hidden observer has also been observed in to baseline control subjects, this counts as an hypnotic deafness (Crawford et al., 1979). instance of negative phonological priming, Hypnotically deaf subjects continue to man­ and thus of implicit perception as well. ifest speech dysfluencies when subjected to delayed auditory feedback (Scheibe, Gray, & Implicit Perception in Hypnotic Blindness Keirn, 1968; Sutcliffe, 1961) and in the case of unilateral deafness show substantial num­ Similar paradoxes are observed in the visual bers of intrusions from material presented domain. Inspired by an earlier experimen­ to their deaf ear (Spanos, Jones, & Malfara, tal case study of hypnotic blindness (Brady, 1982). Nor does hypnotic deafness abol­ 1966; Brady & Lind, 1961; see also Bryant ish the "beats" produced by dissonant tones & McConkey, 1989d; Grosz & Zimmerman, (Pattie, 193 7) or cardiovascular responses to 1965), Sackeim and his colleagues (Sack­ an auditory conditioned stimulus (Sabourin, eim, Nordlie, & Gur, 1979) asked a hyp­ Brisson, & Deschamb, 1980 ). notically blind subject to solve a puzzle in Spanos and Jones (Spanos et al., 1982) which the correct response was indicated preferred to interpret their findings as reveal­ by the illumination of a lamp. Performance ing that hypnotically deaf subjects heard per­ was significantly below chance. Bryant and fectly well, but Sutcliffe ( 196o, 1961) offered McConkey (1989a,b) conducted a similar a more subtle interpretation. In his view, the experiment, with a larger group of subjects, persisting effects of delayed auditory feed­ generally finding above-chance performance. back certainly contradicted the "credulous" The difference in outcomes may reflect a view that hypnotic deafness was identical number of factors, including the subjects' to the actual stimulus state of affairs that motivation for the experiment and individ­ might arise from damage to the auditory ual differences in cognitive style (Bryant & nerve or lesions in the auditory projec­ McConkey, 199oa,b,c), but either outcome tion area - or, for that matter, the simple shows that the visual stimulus was processed absence of an auditory stimulus (Erickson, by the hypnotically blind subjects. 1938a,b). But instead of drawing the "skep­ Dissociations between explicit and tical" conclusion that hypnotized subjects implicit perception are also suggested by were engaged in mere role-playing activity, a series of studies by Leibowitz and his Sutcliffe suggested that they were deluded colleagues, who found that ablation o£ about their experiences that is, that they the background did not affect perception believed that they heard nothing, when in of the Ponzo illusion (Miller, Hennessy, fact they did. Sutcliffe's emphasis on delu­ & Leibowitz, 1973) and that suggestions sion can be viewed as an anticipation of for tubular (tunnel) vision had no effect Hilgard's (1977) neodissociation theory of on the size-distance relation (Leibowitz, divided consciousness, where the subjects' Lundy, & Guez, 1980) or on illusory feelings delusional beliefs reflect their actual phe­ of egomotion (roll vection) induced by nomenal experience, and the evidence of viewing a rotating object (Leibowitz, Post, preserved hearing reflects something like Rodemer, Wadlington, & Lundy, 198o). implicit perception. These experiments are particularly inter­ Only one study has used priming to exam­ esting because they make use of a class of ine implicit perception in hypnotic deafness. perceptual phenomena known as perceptual Nash and his colleagues found that hyp­ couplings, which are apparently inviolable notic deafness reduced the likelihood that links between one perceptual organization CONSCIOUSNESS IN HYPNOSIS 457

and another (Epstein, 1982; Hochberg, hypnotic blindness compared to trials where 1974; Hochberg & Peterson, 1987; Peterson the subjects saw the primes clearly, but any & Hochberg, 1983). If an observer sees evidence of priming counts as evidence of two lines converging in a distance, he or implicit perception- and the magnitude of she must see two identical horizontal bars priming in both studies was substantial by arranged vertically along these lines as any standards. ~ differing in length. In the Miller et al. study, I ablation of the converging lines is a failure ~ Color, Mea.ning. and the Stroop Effect I of explicit perception, but the persistence l of the perceptually coupled Ponzo illusion In addition to total (binocular or uniocu­ indicates that they have been perceived lar) or tubular blindness, hypnotic subjects implicitly. can also be given suggestions for color blind­ Perceptual couplings also seem to be ness. Although some early research indi­ involved in the finding of Blum and his col­ cated that hypnotic colorblindness affected leagues that hypnotic ablation of surround­ performance on the Ishihara test and other ing stimuli did not alter either the magni­ laboratory-based tests of color perception tude of the Titchener-Ebbinghaus illusion (Erickson, 1939), the claim has long been (Blum, Nash, Jansen, & Barbour, 1981) or the controversial (Grether, 1940; Harriman, perception of slant in a target line (Jansen, 1942a,b), and the most rigorous study of Blum, & Loomis, 1982 ). They are also impli­ this type found no effects (Cunningham & cated in the observation that hypnotic anes­ Blum, 1982). Certainly, hypnotically color­ thesia of the forearm does not affect percep­ blind subjects do not show patterns of test tual adaptation of the pointing response to performance that mimic those of the con­ displacing prisms (Spanos, Dubreuil, Saad, & genitally colorblind. Nor do hypnotic sug­ Gorassini, 1983; Spanos, Gorassini, & Petru­ gestions for colorblindness abolish Stroop sic, 1981; Spanos & Saad, 1984). The subjects interference effects (Harvey & Sipprelle, may not feel their arms moving during the 1978; Mallard & Bryant, 2001). All of these pointing trials, but the fact that adaptation results are consistent with the hypothesis occurs indicates that the kinesthetic infor­ that color is processed implicitly in hypnot­ mation has been processed anyway. 6 ically induced colorblindness, even if it is Although the evidence from perceptual not represented in the subjects' phenome­ couplings is consistent with the notion of nal awareness. spared implicit perception, only two stud­ However, hypnotic suggestions of a dif­ ._' ies have used priming methodologies to seek ferent sort may indeed abolish Stroop inter­ evidence of unconscious vision in hypnotic ference. Instead of suggesting that subjects blindness. Bryant and McConkey (1989a) were colorblind, Raz and his colleagues sug­ showed subjects pairs of words consisting of gested that the color words were "meaning­ a homophone and a disambiguating context less symbols ... like characters of a foreign word (e.g., window-pane), half under con­ language that you do not know ... gibberish" ditions of ordinary vision and half during (Raz, Shapiro, Fan, & Posner, 2002, p. 1157 ). hypnotically suggested blindness. On a later The focus on meaning, rather than color, memory test, the subjects generally failed makes this suggestion more akin to the to recall words they had been shown while hypnotic agnosia (or, perhaps, alexia) stud­ blind. On a subsequent test, however, when ied by Spanos and his colleagues in rela­ the words were presented auditorially, they tion to hypnotic amnesia (Spanos, Radtke tended to spell them in line with their ear­ et al., 1982 ). In contrast to the effects of lier visual presentation (e.g., pane rather than suggested colorblindness, suggested agnosia pain). A subsequent study found a similar completely abolished the Stroop interfer­ priming effect on word-fragment comple­ ence effect. Subsequent research, employ­ tion (Bryant & McConkey, 1994). In both ing a drug to induce cycloplegia and thus cases, priming was diminished somewhat by eliminate accommodation effects, ruled out THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS

peripheral mechanisms, such as visual blur­ and implicit emotion (Kihlstrom, Mulvaney, ring or looking away from the stimulus (Raz Tobias, & Tobis, 2000 ).7 Kihlstrom et aL et aL, 2003). However, preliminary fMRI have proposed that, in the absence of self­ research suggests that the reduced Stroop reported emotion, behavioral and physio­ interference reflects a nonspecific dampen­ logical indices of emotional response, such ing of visual information processing (Raz, as facial expressions and heart rate changes, Fan, Shapiro, & Posner, 2002) - a general­ might serve as evidence of implicit, uncon­ ized effect of visual information processing, scious emotional responding. In fact, a study rather than an effect mediated at linguistic by Bryant and Kourch found that hypnotic or semantic levels. This generalized effect on suggestions for emotional numbing dimin­ visual information processing may explain ished self-reported emotional responses, but why Stroop interference did not persist as an had no effect on facial expressions of emo­ implicit expression of semantic processing, tion (Bryant & Kourch, 2001). Although despite the conscious experience of agnosia. this finding is suggestive of a dissociation between explicit and implicit expressions of emotion, two other studies found that Implicit Emotion emotional numbing diminished both subjec­ Hypnotic suggestions can alter conscious tive reports and facial expressions (Bryant emotion as well as perception and memory. & Mallard, 2002; Weiss et aL, 1987 ). With In fact, the suggested alteration of emotion respect to the dissociation between explicit has been a technique for psychotherapy at and implicit emotion, then, the effects of least since the time of Janet (Ellenberger, hypnotically induced emotional numbing 1970 ), and has played a role in hypnotic are currently uncertain. studies of psychodynamic processes (Blum, 1961, 1967, 1979; Reyher, 1967 ). Aside from Anomalies ofDissociation in Hypnosis its inclusion in an advanced scale of hyp­ notic susceptibility (Hilgard, 196 5), the phe­ Most of the classic phenomena of hypnosis nomenon and its underlying mechanisms amnesia, analgesia, and the like appear to have not been subject to much empirical be dissociative in two related but different study. However, more recent studies leave senses. In the first place, hypnotized sub­ little doubt that hypnotic suggestions can jects lack awareness of percepts and mem­ alter subjects' conscious feeling states, just ories that would ordinarily be accessible to as they can alter their conscious percepts consciousness. This disruption in conscious and memories (Bryant & McConkey, 1989c; awareness is the hallmark of the dissociative Weiss, Blum, & Gleberman, 1987 ). disorders encountered clinically, including As with perception and memory; how­ "functional" amnesia and "hysterical" deaf­ ever, special interest attaches to the ques­ ness. In the second place, these percepts tion of whether the "blocked" emotional and memories continue to influence the responses can nevertheless influence the subject's ongoing experience, thought, and person's ongoing experience, thought, and action outside awareness creating dissocia­ action outside of conscious awareness. Until tions between explicit and implicit memory, recently, the idea of unconscious emo­ or explicit and implicit perception, similar tion has generally been seen as a holdover to those that have now become quite famil­ from an earlier, more psychodynamically iar in the laboratory or neurological clinic. As oriented period in the history of psychol­ Hilgard (1977) noted, it is as if consciousness ogy. However, in an era where dissociations has been divided, with one stream of mental between explicit and implicit perception life (e.g., a failure of conscious recollection) and memory are widely accepted as evidence proceeding in phenomenal awareness while of unconscious cognitive processing, there another stream (e.g., the implicit expression seems little reason to reject out of hand the of memory encoding, storage, and retrieval) prospect of dissociations between explicit proceeds outside of awareness. CONSCIOUSNESS IN HYPNOSIS 459

Co-Consciousness and Trance Logic Bryant, Bibb, & Kihlstrom, 1991). Spanos (Spanos, DeGroot, & Gwynn, 1987) sug­ Sometimes, however, the suggested and gested that the occurrence of trance logic actual state of affairs are both represented was an artifact of incomplete response to the in conscious awareness, leading to a set of suggestion on the part of the subject, but this inconsistencies and paradoxes that Orne, in proposal seems to be based on the assump­ a classic paper, labeled "trance logic" (Orne, tion that a" complete" image or hallucination 1959). Orne defined trance logic as the would be tantamount to "the real thing" "apparently simultaneous perception and the actual perceptual state of affairs pro­ response to both hallucinations and reality duced by an adequate environmental stimu­ without any apparent attempts to satisfy a lus. On the other hand, it may well be that need forlogical consistency" (p. 2 9 5) -or, as the hallucination is quite complete, in the he often put it in informal conversation, "the sense of being subjectively compelling to the peaceful coexistence of illusion and reality." person who experiences it but the accom­ For example, in the double hallucination, it panying division of consciousness might be is suggested that the subject will see and incomplete. In this case, trance logic reflects interact with a confederate sitting in a chair a kind of co-consciousness in which two dif­ that is actually empty. When the subject's ferent and mutually contradictory streams of attention is drawn to the real confederate, mental activity - one perceptual, one imag­ who has been quietly sitting outside his or inary - are represented simultaneously in her field of vision, Orne reported that hyp­ phenomenal awareness. notized subjects typically maintained both the perception of the real confederate and Making the Unconscious Conscious the hallucinations, exhibiting confusion as to which was the real confederate. Similarly, In the case of posthypnotic amnesia and hyp­ many subjects reported that they could see notic analgesia, as well as the hypnotic esthe­ through the hallucinated confederate to the sias and negative hallucinations, it seems back of the armchair. Thus, the subjects were that hypnotized subjects are able to become simultaneously aware of two mutually con­ unaware of percepts and memories that tradictory states of affairs, apparently with­ would ordinarily be represented in phenom­ out feeling the need to resolve the contra­ enal awareness. In contrast, it has some­ dictions inherent in the experience. times been suggested that hypnosis also has Orne's initial report of trance logic was the opposite capacity to enable subjects somewhat impressionistic in nature, but to become aware of percepts and memo­ later investigators have attempted to study ries that would not ordinarily be accessible the phenomenon more quantitatively - to conscious introspection. For example, in with somewhat mixed results (Hilgard, hypnotic hypermnesia subjects receive sug­ 1972; R.F.Q. Johnson, 1972; Johnson, Maher, gestions that they will be able to remember & Barber, 1972; McConkey, Bryant, Bibb, events that they have forgotten. In hypnotic Kihlstrom, & Tataryn, 1990; McConkey & age regression, it is suggested that they will Sheehan, 198o; Obstoj & Sheehan, 1977; relive a previous period in their lives - an Sheehan, Obstoj, & McConkey, 1976). On experience that is often accompanied by the the other hand, everyone who has ever apparent recovery of long-forgotten child­ worked with hypnotized subjects has seen hood memories. the phenomenon. Although Orne (Orne, Hypermnesia suggestions are sometimes 1959) held the view that trance logic was employed in forensic situations, with for­ a defining characteristic of hypnosis, this getful witnesses and victims, or in thera­ does not seem to be the case - not least peutic situations, to help patients remember because similar inconsistencies and anoma­ traumatic personal experiences. Although lies of response can occur in ordinary imag­ field studies have sometimes claimed that ination as well as in hypnosis (McConkey, hypnosis can powerfully enhance memory, THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS these reports are mostly anecdotal in nature sis enhanced the recovery of valid mem­ and generally fail to seek independent cor­ ory of actual personal experiences (Hofling, roboration of the memories produced dur­ Heyl, & Wright, 1971). This study has not ing hypnosis. Moreover, they have not been been replicated, however, and another study, supported by studies run under labora­ also employing lifelike stimulus materials - tory conditions. A report by the Com­ a gangland assassination staged before an mittee on Techniques for the Enhance­ audience of law enforcement officers - ment of Human Performance, a unit of the found no advantage for hypnosis whatso­ U.S. National Research Council, concluded ever (Timm, 1981). Perhaps not surpris­ that gains in recall produced by hypnotic ingly, many legal jurisdictions severely limit suggestion were rarely dramatic and were the introduction of memories recovered matched by gains observed when subjects through hypnosis, out of a concern that such are not hypnotized (Kihlstrom & Eich, 1994; memories may be unreliable and tainted Nogrady, McConkey, & Perry, 1985). In fact, by suggestion and inappropriately high lev­ there is some evidence from the labora­ els of confidence. An abundance of caution tory that hypnotic suggestion can interfere seems to be appropriate in this instance, but with normal hypermnesic processes (Reg­ in the present context it seems that hyp­ ister & Kihlstrom, 1987 ). To make things notic suggestion is better at making percepts worse, any increases obtained in valid recol­ and memories inaccessible to consciousness lection can be met or exceeded by increases than it is at making unconscious percepts in false recollections (Dywan & Bowers, and memories accessible to phenomenal 1983). Moreover, hypnotized subjects (espe­ awareness. cially those who are highly hypnotizable) may be vulnerable to distortions in mem­ ory produced by leading questions and Automaticity in Hypnosis other subtle, suggestive influences (Sheehan, 1988). Even before the discovery of implicit mem­ Similar conclusions apply to hypnotic ory and the rediscovery of "subliminal" per­ age regression (Nash, 1987). Although age­ ception, psychology's renewed interest in regressed subjects may experience them­ unconscious mental life was signalled by the selves as children and may behave in a child­ general acceptance of a distinction between like manner, there is no evidence that they automatic and controlled mental processes. actually undergo either abolition of char­ As a first approximation, automatic pro­ acteristically adult modes of mental func­ cesses are executed unconsciously in a tioning or reinstatement of childlike modes reflex-like fashion, whereas controlled pro­ of mental functioning. Nor do age-regressed cesses are executed consciously and delib­ subjects experience the revivification of for­ erately (Kihlstrom, 1987, 1994b). A popu­ gotten memories of childhood. Hypnotic age lar example of automaticity is the Stroop regression can be a subjectively compelling color-word effect, in which subjects have experience for subjects, but it is first and difficulty naming the colors in which words foremost an imaginative experience. As with are printed when the words themselves hypnotic hypermnesia, any memories recov­ name a different color (MacLeod, 1991, 1992; ered during hypnotic age regression cannot Stroop, 193 5). Despite the subjects' con­ be accepted at face value, in the absence of scious intention to name the ink colors independent corroboration. and to ignore the words, they automatically Some clinical practitioners have objected process the words anyway, and this pro­ to these conclusions, on the ground that cessing activity interferes with the naming laboratory studies of memory generally task. lack ecological validity (Brown, Scheflin, & According to traditional formulations Hammond, 1998). In fact, one diary-based (LaBerge & Samuels, 1974; Posner & Snyder, study did find some evidence that hypno- 1975; Schneider & Shiffrin, 1977; Shiffrin & CONSCIOUSNESS IN HYPNOSIS

Schneider, 1977, 1984), automatic processes as voluntary doings (Sarbin & Coe, 1972). share five properties in common: Not all responses to hypnotic suggestion are experienced as completely involuntary, but 1. Inevitable Evocation: Automatic pro­ the experience is strongest among those who cesses are necessarily engaged by the are most highly hypnotizable (Bowers, 1982; appearance of specific cues in the stimu­ Bowers, Laurence, & Hart, 1988). lus environment, independent of the per­ Automaticity lies at the · heart of the son's conscious intentions. "social cognitive" theory of hypnosis pro­ 2. Incorrigible Execution: Once invoked, posed by Kirsch and Lynn (Kirsch, 2ooo; automatic processes proceed unalterably Kirsch & Lynn, 1997, 1998 b), which asserts to their conclusion and cannot be modi­ that hypnotic behaviors are generated auto­ fied by conscious activity. matically by subjects' expectancies that they 3. Effortlessness: The execution of an auto­ will occur - much in the manner of a matic process consumes little or no self-fulfilling prophecy (Rosenthal & Rubin, attentional resources and therefore does 1978; Snyder & Swann, 1978). This view, in not interfere with other ongoing mental tum, is rooted in James's (189o) theory of processes. ideomotor action (see also Arnold, 1946), 4· Speed: Automatic processes are executed which held that motor behavior was gener­ rapidly, on the order of seconds or even ated automatically by the person's idea of fractions of a second - too quickly to be it. Conscious control over behavior, then, is vulnerable to conscious control. accomplished by exerting conscious control over one's cognitive and other mental states; 5. Unavailability: Perhaps because they con­ but once a subject attends to a particular sume no attentional resources, perhaps idea, the resulting behavior occurs naturally. because they are fast, or perhaps because Kirsch and Lynn's social cognitive, ideo­ they are represented as procedural rather motor theory of hypnosis is distinct from than declarative knowledge (Anderson, Spanos's "sodocognitive" approach (Spanos, 1992 ), automatic processes are uncon­ scious in the strict sense of being unavail­ 1986b), which holds either that subjects fab­ ricate reports of involuntariness to convince able to conscious introspection in princi­ the hypnotist that they are, in fact, deeply ple, and they can be known only by infer­ hypnotized (Spanos, Cobb, & Gorassini, ence from performance data. 1985) or that certain features of the hyp­ notic context lead subjects to misattribute their responses to the hypnotist's sugges­ The Experience ofInvoluntariness tions, instead of to their own voluntary in Hypnosis actions (Spanos, 1986a ). Spanos's latter view, As indicated at the outset of this chapter, that the hypnotic experience of involuntari­ there is much about hypnosis that appears ness is illusory, was also embraced by Weg­ to be automatic. Indeed, the experience of ner (2oo2; but see Kihlstrom, 2oo4b). Work­ involuntariness - sometimes called the clas­ ing from a neuropsychological perspective, sic suggestion effect (Weitzenhoffer, 1974)­ Woody and Bowers have suggested that is part and parcel of the experience of hyp­ the experience of involuntariness is a gen­ nosis. Hypnotic subjects don't simply imag­ uine reflection of the effects of hypnosis on ine heavy objects in their hands and allow frontal-lobe structures involved in executive their arms to lower accordingly. They out­ functioning (Woody & Bowers, 1994; Woody stretch their hands voluntarily, as an act of & Sadler, 1998). ordinary compliance with the hypnotist's On the other hand, it is possible that instruction or request to do so, but when the hypnotic experience of involuntariness he or she starts giving the suggestion they is illusory after all - though not for the rea­ feel the heaviness in their hands, their arms sons suggested by Spanos and Wegner. After drop, as involuntary happenings rather than all, as Shor noted, "A hypnotized subject THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS is not a will-less automaton. The hypnotist some views of hypnosis as an altered state does not crawl inside a subject's body and of consciousness, because the phenomenon take control of his brain and muscles" occurs after the hypnotic state has been (Shor, 1979b, p. 127 ). From the frame­ ostensibly terminated. So far as we can work of Hilgard's neodissociation theory of tell, subjects do not re-enter hypnosis while divided consciousness (Hilgard, 1977; see they are responding to the posthypnotic also Kihlstrom, 1992a), the experience of suggestion. At least, they are not particu­ involuntariness reflects an amnesia-like bar­ larly responsive to other hypnotic sugges­ rier that impairs subjects' conscious aware­ tions during this time (Reyher & Smyth, ness of their own role in producing hypnotic 1971). We cannot say that hypnosis caused responses. In this view, the hypnotic subject the behavior to occur, because the sub­ actively imagines a heavy object in his out­ jects are not hypnotized when they make stretched hand, and actively lowers his hand their response. Nevertheless, some alteration and arm as if it were heavy, but is not aware of consciousness has occurred, because at of doing so. Thus, the subject's behavior is the very least they are not aware of what technically voluntary in nature, but is experi­ they are doing or why (Sheehan & Orne, enced as involuntary- as occurring automat­ 1968). ically- because the subject is unaware of his In the present context, posthypnotic sug­ or her own role as the agent of the behavior. gestion is of interest because it seems to In other words, the apparent disruption of occur automatically in response to the prear­ conscious control actually occurs by virtue of ranged cue (Erickson & Erickson, 1941 ). Cer­ a disruption of conscious awareness - a pro­ tainly posthypnotic suggestion differs from posal that (perhaps) gains credence from the ordinary behavioral compliance. Damaser dissociations between explicit and implicit (Damaser, 1964; see also Orne, 1969) gave memory and perception discussed earlier. subjects a posthypnotic suggestion to mail the experimenter one postcard per day, a control group received an ordinary social Automaticity in Posthypnoti& Suggestion request to perform the same behavior, and a Perhaps the most dramatic demonstration third group received both the posthypnotic of apparent automaticity in hypnosis is suggestion and the social request. Surpris­ posthypnotic suggestion, in which the sub­ ingly, the subjects who received the social ject responds after the termination of hyp­ request mailed more postcards than did nosis to a suggestion administered while he those who received only the posthypnotic or she was still hypnotized. On the group­ suggestion (see also Barnier & McConkey, administered HGSHS:A, for example, it 1999b). Apparently, those who agreed to is suggested that when the subjects hear the social request felt that they were under two taps, they will reach down and touch some obligation to carry it out, but those their left ankles, but forget that they were who received the posthypnotic suggestion instructed to do so. After the termination of carried it out only so long as they felt the hypnosis, many highly hypnotizable subjects urge to do so. This urge can be powerful: will respond quickly to such a prearranged Subjects who fail to respond to a posthyp­ cue-without knowing why they are doing so notic suggestion on an initial test appear to or confabulating a reason, such as that they show a persisting tendency to perform the feel an itch. They may even be unaware that suggested behavior at a later time (Nace & they are doing anything unusual at all. Orne, 1970). Posthypnotic behavior can per­ Any suggested experience that can occur sist for long periods of time (Edwards, 1963 ), during hypnosis can also occur posthypnoti­ even after the posthypnotic suggestion has cally, provided that the subject is sufficiently been formally canceled (Bowers, 1975). hypnotizable. For this reason, posthypnotic Nevertheless, close examination shows suggestion has always been problematic for that posthypnotic behavior does not meet CONSCIOUSNESS IN HYPNOSIS

the technical definition of automaticity, and influences subsequent behavior in the as it has evolved within cognitive psy­ absence of conscious recollection. chology (Bamier, 1999). In the first place, posthypnotic suggestion fails the test of inevitable evocation. Except under special Hypnosis in Mind and Body circumstances (Orne, Sheehan, & Evans, 1968), response to a posthypnotic sugges­ Researchers have long been interested in bio­ tion declines markedly outside the experi­ logical correlates of hypnosis. In the 19th mental context in which the suggestion is century, Braid likened hypnosis to sleep, originally given (Barnier & McConkey, 1998; whereas Pavlov considered it to be a state of Fisher, 1954; Spanos, Menary, Brett, Cross, corticalinhibition (Gauld, 1992 ). In the mid­ & Ahmed, 1987). Moreover, like all other zoth century revival of interest in conscious­ aspects of hypnosis, posthypnotic behavior ness, some theorists speculated that hyp­ depends intimately on the both the subject's nosis entailed an increase in high-voltage, interpretation of the hypnotist's suggestion low-frequency alpha activity in the EEG, and the context in which the cue appears though this proved to be an artifact of relax­ (Bamier & McConkey, 1999a, 2001). It is ation and eye closure (Dumas, 1977; Evans, in no sense reflexive in nature. Moreover, 1979b). The discovery of hemispheric spe­ posthypnotic suggestion is not effortless. Sub­ cialization, with the left hemisphere geared jects respond to simple posthypnotic sug­ to analytic and the right hemisphere to non­ gestions more frequently than to complex analytic tasks, coupled with the notion that ones (Barnier & McConkey, 1999c), sug­ the right hemisphere is "silent" or uncon­ gesting that the activity makes demands on scious," led to the speculation that hypnotic the subject's information-processing capac­ response is somehow mediated by right­ ity. Responding to a posthypnotic sugges­ hemisphere activity (Bakan, 1969). Studies tion interferes with responding to a waking employing both behavioral and electrophys­ instruction, even when the response require­ iological paradigms (e.g., MacLeod-Morgan ments of the two tasks do not conflict (Hoyt & Lack, 1982; Sackeim, 1982) have been & Kihlstrom, 1986). Thus, responding to a interpreted as indicating increased activa­ posthypnotic suggestion seems to consume tion of the right hemisphere among highly more information-processing capacity than hypnotizable individuals, but positive results would be expected of a truly automatic have proved difficult to replicate (e.g., process. Graffin, Ray, & Lundy, 1995; Otto-Salaj, Posthypnotic suggestion does not appear Nadon, Hoyt, Register, & Kihlstrom, 1992), to be an instance of automaticity, but it and interpretation of these findings remains does appear to be an instance of prospec­ controversial. tive memory (Einstein & McDaniel, 1990 ), It should be understood that hypnosis in which subjects must remember to per­ is mediated by verbal suggestions, which form a specified activity at some time must be interpreted by the subject in the in the future. Awareness of the posthyp­ course of responding. Thus, the role of notic suggestion does not seem to inter­ the left hemisphere should not be min­ fere with posthypnotic behavior (Bamier imized (Jasiukaitis, Nouriani, Hugdahl, & & McConkey, 1999c; Edwards, 1956; Gan­ Spiegel, 1995; Rainville, Hofbauer, Paus, dolfo, 1971). But when accompanied by Bushnell, & Price, 1999). One interesting posthypnotic amnesia, posthypnotic behav­ proposal is that hypnotizable individuals , ior takes on some of the qualities of implicit show greater flexibility in deploying the left , memory. Even though subjects may for­ and right hemispheres in a task-appropriate get the suggestion, the fact that they carry manner, especially when they are actually out the suggestion on cue shows clearly that hypnotized (Crawford, 2o01; Crawford & the prospective memory has been encoded Gruzelier, 1992). Because involuntariness THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS

is so central to the experience of hyp­ Maquet et al. asked their subjects to review nosis, it has also been suggested that the a pleasant life experience (Maquet et al., frontal lobes (which organize intentional 1999). action) may play a special role in hyp­ Although the concept of "neutral" hyp­ nosis, and especially in the experience of nosis has had its proponents (Kihlstrom involuntariness (Woody & Bowers, 1994; & Edmonston, 1971), in subjective terms Woody & Sadler, 1998). Along these lines, the state, such as it is, differs little from Farvolden and Woody have found that eyes-dosed relaxation (Edmonston, 1977, highly hypnotizable individuals perform 1981) and bears little resemblance to the relatively poorly on neuropsychological dissociative and hallucinatory experiences tasks that assess frontal-lobe functioning associated with specific hypnotic sugges­ (Farvolden & Woody, 2004). tions. Moreover, it is unlikely that imaging subjects who are merely in neutral hypno­ sis and not responding to particular hyp­ "Neutral" Hypnosis notic suggestions will tell us much about the Although most work on the neural correlates neural correlates of hypnosis, because the of hypnosis has employed psychophysiolog­ experiences of hypnotic subjects are so var­ ical measures such as the EEG and event­ ied, depending on the suggestion to which related potentials, it seems likely that a bet­ they are responding. A more fruitful tack ter understanding of the neural substrates will likely involve imaging subjects while of hypnosis may come from the applica­ they are responding to particular hypnotic tion ofbrain imaging technologies (Barnier & suggestions. Just as the neural correlates of McConkey, 2003; Killeen&Nash,2oo3; Ray NREM sleep differ from those of REM sleep & Tucker, 2003; Woody & McConkey; 2003; (Hobson, Pace-Schott, & Stickgold, 2000 ), Woody & Szechtman, 2003). One approach so the neural correlates of neutral hypnosis has been to scan subjects after they have will differ from those of specific, suggested received a hypnotic induction but before hypnotic phenomena. they have received any specific suggestions, on the assumption that such a procedure will Hypnotic Analgesia reveal the neural correlates (if indeed any exist) of hypnosis as a generalized altered Perhaps because of the added interest value state of consciousness. For example, one PET that comes with clinical application, most study found that the induction of hypnosis brain imaging studies of hypnotic sugges­ generated widespread activation of occipital, tions have focused on analgesia. A pio­ parietal, precentral, premotor, and ventro­ neering study using the '33 Xe technique lateral prefrontal cortex in the left hemi­ found bilateral increases in the activation sphere, and the occipital and anterior cin­ of the orbitofrontal region, as well as in gulate cortex of the right hemisphere - in somatosensory cortex, during analgesia com­ other words, pretty much the entire brain pared to resting baseline and a control (Maquet et al., 1999). At the same time, condition in which subjects attended to another PET study found that the induction the pain (Crawford, Gur, Skolnick, Gur, & of hypnosis was accompanied by increased Benson, 1993). They suggested that these activation of occipital cortex and decreases changes reflected the increased mental effort in the right inferior parietal lobule, left pre­ needed to actively inhibit the process­ cuneus, and posterior cingulate (Rainville, ing of somatosensory information. A more Hofbauer et al., 1999). As is so often the recent PET study implicated quite different case in brain imaging experiments, the dif­ regions, particularly the anterior cingulate ference in results may be due to differences cortex (ACC). However, this later study also in control conditions. Whereas Rainville employed quite a different procedure, mod­ et al. asked their hypnotized subjects simply ulating pain perception through a pleasant to relax (Rainville, Hofbauer et al., 1999), autobiographical reverie instead of a specific CONSCIOUSNESS IN HYPNOSIS

suggestion for analgesia (Faymonville et al., ing from the external stimulus environment 2000). (Woody & Szechtman, 2oooa,b). Another Because the specific wording of sugges­ interpretation, based on the role of ACC tions is so important in hypnosis, perhaps in emotion, is that the activity in this the most interesting brain imaging studies region reflects affective arousal to experi­ r of analgesia compared suggestions targeting ences, whether perceptual or hallucinatory, sensory pain, which relates to the location which surprise the subject; mental images, and physical intensity of the pain stimu­ being deliberately constructed by the sub­ lus, with suggestions targeting suffering, or ject, would not have this surprise value. the meaning of the pain (Melzack, 1975). In another study, Kosslyn and his col­ Standard hypnotic suggestions for analge­ leagues studied the modulation of color sia affect both sensory pain and suffering perception through hypnotic suggestion (Hilgard & Hilgard, 1975), but these two (Kosslyn et al., 2ooo ). After PET imaging dimensions can also be dissociated by alter­ identified a region (in the fusiform area) that ing the specific wording of the suggestion was differentially activated by the presen­ (Rainville, Carrier, Hofbauer, Bushnell, & tation of chromatic and gray-scale stimuli, Duncan, 1999). Using hypnotic suggestions, these investigators gave suggestions to highly Rainville and his colleagues have found that hypnotizable subjects that they would per­ .. suggestions that alter the unpleasantness of a ceive the colored stimulus in gray scale, pain stimulus, without altering its intensity, and the gray-scale stimulus as colored. The are associated with changes in ACC but not result was that the fusiform region was acti­ in somatosensory cortex (Rainville, Duncan, vated in line with subjects' perceptions I Price, Carrier, & Bushnell, 1997; Rainville actual and hallucinated color or actual and et al., 2002 ). hallucinated gray scale, independent of the stimulus. In contrast to nonhypnotic color imagery, which appears to activate only HaHucinations and Imagery I the right fusiform region (Howard et al., Brain imaging studies also bear on the rela­ 1998), hypnotically hallucinated color acti­ tion between hypnotic hallucinations and vated both the left and right hemispheres. normal imagery. On the surface, at least, Taken together with the Szechtman et al. imagery would seem to be a cognitive study (1998), these results suggest that hyp­ I skill relevant to hypnosis, and some theo­ notic hallucinations are in at least some sense rists sometimes write as if hypnosis were distinct from mental images. only a special case of a larger domain of mental imagery (for reviews, see Bow­ I ers, 1992; Glisky et al., 1995; Kunzen­ Brain States and States dorf, Spanos, & Wallace, 1996; Sheehan, of Consciousness 1982 ). On the contrary, Szechtman and his colleagues found that hypnotized subjects The controversy over the very nature of hyp­ experiencing suggested auditory hallucina­ nosis has often led investigators to seek evi­ l tions showed activation of the right ACC; dence of neural and other biological changes this area was also activated during normal to demonstrate that hypnosis is "real" - or, hearing, but not during auditory imagery alternatively, to debunk the phenomenon as (Szechtman, Woody, Bowers, & Nahmias, illusion and fakery. For example, the lack of I 1998). Interestingly, a parallel study found reliable physiological correlates of hypnotic , that schizophrenic patients also showed response has been interpreted by Sarbin right ACC activation during their audi­ as supporting his role-enactment interpre­ tory hallucinations (Cleghorn et al., 1992). tation of hypnosis (Sarbin, 1973; Sarbin & I They suggested that activation of this region Slagle, 1979). On the other hand, Kosslyn might cause internally generated thoughts and his colleagues argued that the activity I and images to be confused with those aris- of the fusiform color area in response to THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS suggestions for altered color vision "support that makes for consciousness. And the neu­ the claim that hypnosis is a psychological ral correlates of that difference are the neural state with distinct neural correlates and is correlates of consciousness. not just the result of adopting a role" (Koss­ lyn et al., 2ooo, p. 1279). Neither position is quite correct. Physio­ Acknowledgements logical correlates are nice when they exist, and they may enable otherwise skeptical The point of view represented in this paper is observers to accept the phenomena of hyp­ based on research supported by Grant #MH- nosis as real. But such correlates are neither 3 5 85 6 from the National Institute of Mental necessary nor sufficient to define an altered Health. state of consciousness. In the final analysis, consciousness is a psychological construct, not a biological one, and can only be defined Notes at a psychological level of analysis. The phe­ nomena of hypnosis - amnesia, analgesia, 1. This was true even before hypnosis received positive and negative hallucinations, and the its name (Braid, 1843; Gravitz & Gerton, like -obviously represent alterations in con­ 1984; Kihlstrom, 1992c) and for that mat­ scious perception and memory. The neural ter even before that, the status of hypnosis correlates of these phenomena are a matter as an altered organismal state was controver­ sial. In the 18th century, Mesmer thought his of considerable interest, but they are another "crises" were induced by animal magnetism, matter entirely. but the Franklin Commission chalked them At the same time, the phenomena of hyp­ up to mere imagination (Kihlstrom, :zoo:zb). In nosis seem to offer a unique vantage point the 19th century, Charcot thought that hypno­ from which consciousness and its neural cor­ sis was closely related to hysteria and to neu­ relates can be studied, because they remind rological disease, whereas Liebeault and Bern­ us that consciousness is not just a matter of heim attributed its effects to simple sugges­ attention and alertness. Mental states are also tion. Perhaps because he was writing in the a matter ofaboutness: They have intentional­ heyday of functional behaviorism, Hull (193 3) ity, in that they refer to objects that exist and did not confront the "state-nonstate" issue: For events that occur in the world outside the him, hypnosis was an intrinsically interesting phenomenon that psychology ought to be able mind. Hypnotized subjects are conscious, in to explain (Kihlstrom, 2004a). the sense of being alert and attentive, but 2. Lacking the explicit-implicit distinction sub­ when certain suggestions are in effect they sequently introduced by Schacter (see also are not conscious of some things - of some Graf & Schacter, 1985; Schacter, 1987; Schac­ event in the past or some object in their cur­ ter & Graf, 1986 ), Kihlstrom noted simply that rent environment. The fact that percepts and the priming represented "a residual effect of memories can be explicit or implicit means the original learning episode on a subsequent that mental states themselves can be con­ task involving retrieval from 'semantic' mem­ scious or unconscious. ory" (p. 246 ), that it "took place outside of phe­ The phenomena of hypnosis remind us nomenal awareness," and that it was "similar to that there is a difference between being one which occurs in patients diagnosed with aware of something explicitly and being the amnesic syndrome" (p. 246). A similar unaware of something that nonetheless, interpretation appeared in 198 5 (Kihlstrom, 1985), in a paper that had been written in implicitly influences our ongoing experi­ 1984, and the relevance of the explicit-implicit ence, thought, and action. Almost uniquely, distinction was made explicit (sorry) in 1987 hypnosis allows us to create, and reverse, (Kihlstrom, 1987 ). dissociations between the explicit and 3 . Interestingly, David et al. obtained a similar the implicit-between the conscious and the pattern of results for directed forgetting in unconscious at will in the laboratory. The the normal waking state. Posthypnotic amne­ difference between implicit and explicit per­ sia and directed forgetting are both exam­ cepts and memories, then, is the difference ples of retrieval inhibition (Anderson & Green, CONSCIOUSNESS IN HYPNOSIS

2001; Anderson et al., 2004; Geiselman, Bjork, Glover, G. H., & Gabrieli, 1. D. E. (2004). & Fishman, 1983; Levy & Anderson, 2002), Neural systems underlying the suppression of but the two paradigms generally differ greatly unwanted memories. Science, 3 03, 2 p-2 3 5. in other respects (Kihlstrom, 1983); for exam­ Arnold, M. B. (1946). On the mechanism of sug­ ple, the role of incidental or intentional learn­ gestion and hypnosis. Journal of Abnormal and ing, the amount of study devoted to the items, Social Psychology, 41, 107-128. the temporal location of the cue to forget. As, A. (1962). Non-hypnotic experiences related the retention interval involved, and the means to hypnotizability in male and female college by which memory is measured as well as students. Scandinavian Journal ofPsychology, 3, the degree to which the to-be-forgotten items 112-121. are actually inaccessible, whether the forget­ Aserinsky, E., & Kleitman, N. (1953). Regularly ting is reversible, and the extent of inter­ occurring periods of eye motility, and concomi­ ference between to-be-forgotten and to-be­ tant phenomena, during sleep. Science, n8, remembered items. 273-274· 4· Source amnesia is a failure of source monitor­ Bakan, P. ( 1969). Hypnotizability, laterality of eye ing (Johnson, Hashtroudi, & Lindsay, 1993), a movements and functional brain asymmetry. process that in turn is closely related to reality Perceptual and Motor Skills, 2 8, 92 7--9 32. monitoring (Johnson & Raye, 1981). It proba­ bly lies at the heart of the experience ofdeja vu Banister, H., & Zangwill, 0. L. (1941a). Experi­ (Brown, 2003). As noted by Evans and Thome mentally induced olfactory paramnesia. British (1966), their work had been anticipated by Journal of Psychology, 32,155-175- Banister and Zangwill ( 1941a, b) who used hyp­ Banister, H., & Zangwill, 0. L. (1941b ). Exper­ notic suggestion to produce visual and olfac­ imentally induced visual paramnesias. British tory "paramnesias" in which subjects recognize Journal of Psychology, 32, 30-51. t a previously studied item but confabulate the Barber, J., & Mayer, D. (1977 ). Evaluation of effi­ context in which it has been studied. cacy and neural mechanism of a hypnotic anal­ 5 . A thorough discussion of experimental and gesia procedure in experimental and clinical clinical research on hypnotic analgesia is dental pain. Pain, 4, 41-48. I beyond the scope of this chapter. Interested Barber, T. X. (1969). Hypnosis: A scientific .. readers may wish to consult Kihlstrom (2ooo, approach. New York: Van Nostrand Reinhold. 2001b). Barber, T. X., & Calverley, D. S. (1966). Toward 6. Note, however; Wallace and his colleagues a theory of "hypnotic" behavior: Experimental have found that hypnotic anesthesia actu­ analyses of suggested amnesia. Journal ofAbnor­ ally abolishes prism adaptation, so this find­ mal Psychology, 71,95-107. l ing remains in some dispute (Wallace, 198o; Barnier, A. 1. (1997). Autobiographical amnesia: Wallace & Fisher, 1982, 1984a,b; Wallace & An investigation of hypnotically created per­ Garrett, 1973, 1975). sonal forgetting. Proposal to Australian Research 7. McClelland and his colleagues have made a Council. l distinction between explicit (conscious) and Bamier, A. 1. (1999). Posthypnotic suggestion: implicit (unconscious) motivation, as well Attention, awareness, and automaticity. Sleep (McClelland, Koestner; & Weinberger; 1989), & Hypnosis, 1t 57-63. [ but to date there have been no studies of hyp­ Bamier, A. 1. (2oo2). Posthypnotic amnesia for nosis along these lines. autobiographical episodes: A laboratory model of functional amnesia? Psychological Science, 13(3), 232-237· References Barnier, A. 1., Bryant, R. A., & Briscoe, S. (2001). t Posthypnotic amnesia for material learned Anderson, 1. R. (1992). Automaticity and the before or during hypnosis: Explicit and implicit ACT* theory. American Journal of Psychology, memory effects. International Journal of Clini­ 105(2), 165-18o. cal and Experimental Hypnosis, 49(4), 286-304. [ Anderson, M. C., & Green, C. (2001, March). Bamier, A. 1., & McConkey, K. M. (1998). Suppressing unwanted memories by executive Posthypnotic responding: Knowing when to control. Nature, 410(15), 366-369. stop helps to keep it going. International Journal Anderson, M. C., Ochsner, K. N., Kuhl, B., of Clinical & Experimental Hypnosis, 46, 204- l Cooper, J., Robertson, Gabrieli, S. W, :1.19. THE CAMBRIDGE HANDBOOK OF CONSCIOUSNESS

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Edited by Philip David Zelazo, Morris Moscovitch and Evan Thompson University of Toronto

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Library of Congress Cataloging in Publication Dara The Cambridge handbook of consciousness I edited by Philip David Zelazo, Morris Moscovitch, Evan Thompson. p. em. Includes bibliographical references and index. ISBN-13: 978-o-521-8574 3-7 (hardback) ISBN-10: o-521-85743-o (hardback) ISBN-13: 978·o-p1-67412-6 (pbk.) ISBN-10: 0-521-67412-3 (pbk.) 1. Consciousness. I. Zelazo, Philip David. II. Moscovitch, Morris, 1945- III. Thompson, Evan. IV. Title. B8o8.9.q6 2007 15 3 dc22 2oo6m3 84 3

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