DOCSLIB.ORG

Semantic Encoding and Retrieval in the Left Inferior Prefrontal Cortex: a Functional MRI Study of Task Difficulty and Process Specificity

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Semantic Encoding and Retrieval in the Left Inferior Prefrontal Cortex: a Functional MRI Study of Task Difficulty and Process Specificity The Journal of Neuroscience, September 1995, 15(g): 5870-5878 Semantic Encoding and Retrieval in the Left Inferior Prefrontal Cortex: A Functional MRI Study of Task Difficulty and Process Specificity Jonathan B. Demb,’ John E. Desmond,2 Anthony D. Wagner,’ Chandan J. Vaidya,’ Gary H. Glover,2 and John D. E. Gabriel? Departments of ‘Psychology and ‘Radiology, Stanford University, Stanford, California 94305-2130 Prefrontal cortical function was examined during semantic Lockhart, 1972). Retrieval refers to the recovery of previously encoding and repetition priming using functional magnetic encoded information from long-term memory and can be mea- resonance imaging (fMRI), a noninvasive technique for lo- sured explicitly, by measuresof intentional recollection, or im- calizing regional changes in blood oxygenation, a correlate plicitly, by measuresof priming, conditioning, or skill learning of neural activity. Words studied in a semantic (deep) en- (Graf and Schacter, 198.5).Priming reflects experience-basedfa- coding condition were better remembered than words stud- cilitation in performance with a stimulus that does not depend ied in both easier and more difficult nonsemantic (shallow) on intentional recollection. For example, subjects make a se- encoding conditions, with difficulty indexed by response mantic encoding decision (e.g., is this word abstract‘?)more time. The left inferior prefrontal cortex (LIPC) (Brodmann’s quickly for a repeated than an initial presentation of a word areas 45, 46, 47) showed increased activation during se- (Gabrieli, Desmond,Demb, Wagner, Stone, Vaidya, and Glover, mantic encoding relative to nonsemantic encoding regard- unpublishedobservations). less of the relative difficulty of the nonsemantic encoding Functional magnetic resonanceimaging (fMR1) and positron task. Therefore, LIPC activation appears to be related to emissiontomography (PET) studieshave indicated left inferior semantic encoding and not task difficulty. Semantic encod- prefrontal cortex (LIPC) involvement in semanticencoding. The ing decisions are performed faster the second time words LIPC area (Brodmann’s areas 45, 46, 47), anterior to Broca’s are presented. This represents semantic repetition priming, area, showsgreater activation during semanticthan nonsemantic a facilitation in semantic processing for previously encod- encoding (Gabrieli et al., unpublishedobservations; seeTulving ed words that is not dependent on intentional recollection. et al., 1994). In these studies,the semanticencoding tasks have The same LIPC area activated during semantic encoding been more difficult than nonsemanticencoding tasks, with dif- showed decreased activation during repeated semantic en- ficulty operationalized as the time required to perform an en- coding relative to initial semantic encoding of the same coding task. This difference in difficulty hasbeen shown directly words. This decrease in activation during repeated encod- in two studies(Gabrieli et al., unpublishedobservations; Kapur ing was process specific; it occurred when words were se- et al., 1994) and is likely to be the case in others. One goal of mantically reprocessed but not when words were nonse- the current study was to compare a semanticencoding task to mantically reprocessed. The results were apparent in both both less and more difficult nonsemanticencoding tasks, to in- individual and averaged functional maps. These findings vestigate whether LIPC activation reflects semanticencoding or suggest that the LIPC is part of a semantic executive sys- encoding difficulty. If LIPC activation reflects semanticencod- tem that contributes to the on-line retrieval of semantic in- ing, it should be present during the semanticencoding task rel- formation. ative to both lessand more difficult nonsemanticencoding tasks. [Key words: functional magnetic resonance imaging The sameLIPC area that activates during semanticencoding (fMR/), prefrontal cortex, semantic memory, implicit mem- has also been implicated in semanticrepetition priming. When ory, area 8, executive functioning] words were semantically encodedmore than once, subjectsen- coded more quickly the second time (priming). There was a Encoding and retrieval constitute two discrete stagesof memory. correspondingdecrease in LIPC activation for repeated relative Encoding refers to the processesoperating at the time of learning to initial semanticencoding (Gabrieli et al., unpublishedobser- that determine what information is stored in long-term memory. vations; Raichle et al., 1994). The decreasesin responsetime Different kinds of encoding lead to different kinds of storage. and brain activation representa word-specific effect; when novel For example, words are typically better rememberedwhen en- words were semantically encoded, behavioral responsesand coded for meaning (semantic or “deep” encoding) rather than LIPC activation returned to initial levels (Gabrieli et al., unpub- for appearance(nonsemantic or “shallow” encoding) (Craik and lished observations; Raichle et al., 1994). However, it is un- known whether decreasedLIPC activation reflects a process- Received Jan. 17, 1995; revised May 5, 1995; accepted May IO, 1995. specific change based on semanticreencoding, or rather a pro- This work was supported by research grants from the Stanford University cessnonspecific change based on reexposureto words regardless Office of Technology and Licensing, the Alzheimer’s Association (Blum-Kov- of the encoding processengaged. Therefore, a secondgoal was ler Pilot Research Grant), and the NIH (NINDS lF32NS09628). Correspondence should be addressed to Jonathan Demb at the above address. to clarify the nature of the decreasedLIPC activation during Copyright 0 1995 Society for Neuroscience 0270-6474/95/l 55870-09$05.00/O repeatedsemantic encoding. If decreasedLIPC activation is spe- The Journal of Neuroscience, September 1995, 15(Q) 5871 no more than four ascending or descending words appeared consecu- tively. Procedure. Each subject performed two encoding experiments. Both experiments compared a semantic encoding task, in which subjects had to decide whether words were abstract or concrete (Abstract/Concrete Task), with a nonsemantic encoding task. In the first experiment, sub- jects alternately performed the semantic encoding task and a nonse- mantic encoding task, in which subjects had to decide if words were printed in uppercase or lowercase letters (Uppercase/Lowercase Task). In the second experiment, subjects alternately performed the semantic encoding task and a nonsemantic encoding task, in which subjects had to decide if the tirst and last letter of each word were ascending or descending alphabetically (Ascending/Descending Task). The semantic encoding task required that subjects attend to word meaning, whereas both nonsemantic encoding tasks required that subjects attend to word features (i.e., letters). Subjects saw four sets of 20 words presented consecutively. One encoding task was performed on the first and third set and another task was performed on the second and fourth set. Each pair of tasks consti- tuted a cycle, so that two cycles were performed by each subject in each experiment. An instruction card at the beginning of each set of 20 Figure I. The location of the coronal slices analyzed in this study are words (e.g., Task-Abstract) indicated the target for that set (e.g., abstract depicted as white lines on a sagittal localizer. The slices shown are 32 words). Subjects were instructed to respond as quickly and as accurately and 39 mm rostra1 to the anterior commissure (AC).‘An additional third as possible to the indicated target by pressing a mouse button; they slice, 46 mm rostra1 to the AC was acquired in three subjects in the were instructed to not respond to nontarget words. Words appeared cen- Process Specificity study (see Table I). trally on a computer monitor for a duration of 1 set, followed by a 1 set interval before the next word appeared. For each task, half of the subjects responded to one kind of target (e.g., abstract or uppercase or cific to semantic processes, it should occur during repeated se- ascending) and half the subjects responded to the other kind of target mantic encoding but not during repeated nonsemantic encoding. (e.g., concrete or lowercase or descending). Word orders were kept con- stant across subjects, but the order of alternating encoding tasks was Materials and Methods counterbalanced across subjects. Thus, encoding tasks and responses were counterbalanced across words. After each experiment, subjects Behaviorul study were given a recognition test, composed of 20 studied words, half of The purpose of the behavioral study was to validate a difficult nonse- which were presented in the Abstract/Concrete Task and half of which mantic encoding condition to be used in the Task Difficulty fMR1 ex- were presented in either the Uppercase/Lowercase Task or the Ascend- periment. We predicted that this task would be more difficult than se- ing/Descending Task, and 20 new (foil) words in a random order. Words mantic encoding (longer response time; RT), but would still lead to appeared one at a time on a computer monitor and subjects were in- lower subsequent memory performance than semantic encoding. structed to respond by pressing a mouse button if they thought the Subjects. The subjects were 16 volunteers from the Stanford com- words had been in the study list. Different foil words were used after munity (ages 18-24) who participated for a $10 payment. All subjects each encoding experiment,
Load more

Recommended publications
  • Compare and Contrast Two Models Or Theories of One Cognitive Process with Reference to Research Studies
    ! The following sample is for the learning objective: Compare and contrast two models or theories of one cognitive process with reference to research studies. What is the question asking for? * A clear outline of two models of one cognitive process. The cognitive process may be memory, perception, decision-making, language or thinking. * Research is used to support the models as described. The research does not need to be outlined in a lot of detail, but underatanding of the role of research in supporting the models should be apparent.. * Both similarities and differences of the two models should be clearly outlined. Sample response The theory of memory is studied scientifically and several models have been developed to help The cognitive process describe and potentially explain how memory works. Two models that attempt to describe how (memory) and two models are memory works are the Multi-Store Model of Memory, developed by Atkinson & Shiffrin (1968), clearly identified. and the Working Memory Model of Memory, developed by Baddeley & Hitch (1974). The Multi-store model model explains that all memory is taken in through our senses; this is called sensory input. This information is enters our sensory memory, where if it is attended to, it will pass to short-term memory. If not attention is paid to it, it is displaced. Short-term memory Research. is limited in duration and capacity. According to Miller, STM can hold only 7 plus or minus 2 pieces of information. Short-term memory memory lasts for six to twelve seconds. When information in the short-term memory is rehearsed, it enters the long-term memory store in a process called “encoding.” When we recall information, it is retrieved from LTM and moved A satisfactory description of back into STM.
    [Show full text]
  • Episodic Memory in Transient Global Amnesia: Encoding, Storage, Or Retrieval Deficit?
    J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.66.2.148 on 1 February 1999. Downloaded from 148 J Neurol Neurosurg Psychiatry 1999;66:148–154 Episodic memory in transient global amnesia: encoding, storage, or retrieval deficit? Francis Eustache, Béatrice Desgranges, Peggy Laville, Bérengère Guillery, Catherine Lalevée, Stéphane SchaeVer, Vincent de la Sayette, Serge Iglesias, Jean-Claude Baron, Fausto Viader Abstract evertheless this division into processing stages Objectives—To assess episodic memory continues to be useful in helping understand (especially anterograde amnesia) during the working of memory systems”. These three the acute phase of transient global amne- stages may be defined in the following way: (1) sia to diVerentiate an encoding, a storage, encoding, during which perceptive information or a retrieval deficit. is transformed into more or less stable mental Methods—In three patients, whose am- representations; (2) storage (or consolidation), nestic episode fulfilled all current criteria during which mnemonic information is associ- for transient global amnesia, a neuro- ated with other representations and maintained psychological protocol was administered in long term memory; (3) retrieval, during which included a word learning task which the subject can momentarily reactivate derived from the Grober and Buschke’s mnemonic representations. These definitions procedure. will be used in the present study. Results—In one patient, the results sug- Regarding the retrograde amnesia of TGA, it gested an encoding deficit,
    [Show full text]
  • Post-Encoding Stress Does Not Enhance Memory Consolidation: the Role of Cortisol and Testosterone Reactivity
    brain sciences Article Post-Encoding Stress Does Not Enhance Memory Consolidation: The Role of Cortisol and Testosterone Reactivity Vanesa Hidalgo 1,* , Carolina Villada 2 and Alicia Salvador 3 1 Department of Psychology and Sociology, Area of Psychobiology, University of Zaragoza, 44003 Teruel, Spain 2 Department of Psychology, Division of Health Sciences, University of Guanajuato, Leon 37670, Mexico; [email protected] 3 Department of Psychobiology and IDOCAL, University of Valencia, 46010 Valencia, Spain; [email protected] * Correspondence: [email protected]; Tel.: +34-978-645-346 Received: 11 October 2020; Accepted: 15 December 2020; Published: 16 December 2020 Abstract: In contrast to the large body of research on the effects of stress-induced cortisol on memory consolidation in young people, far less attention has been devoted to understanding the effects of stress-induced testosterone on this memory phase. This study examined the psychobiological (i.e., anxiety, cortisol, and testosterone) response to the Maastricht Acute Stress Test and its impact on free recall and recognition for emotional and neutral material. Thirty-seven healthy young men and women were exposed to a stress (MAST) or control task post-encoding, and 24 h later, they had to recall the material previously learned. Results indicated that the MAST increased anxiety and cortisol levels, but it did not significantly change the testosterone levels. Post-encoding MAST did not affect memory consolidation for emotional and neutral pictures. Interestingly, however, cortisol reactivity was negatively related to free recall for negative low-arousal pictures, whereas testosterone reactivity was positively related to free recall for negative-high arousal and total pictures.
    [Show full text]
  • The Effects of a Suggested Encoding Strategies on Achievement
    The Effects of Metacognition 17 The Effects of Metacognition and Concrete Encoding Strategies on Depth of Understanding in Educational Psychology Suzanne Schellenberg, Meiko Negishi, & Paul Eggen, University of North Florida The study compared the academic achievement, as measured by final examination scores, of an experimental group of undergraduate educational psychology students who were provided with concrete mechanisms designed to promote metacognition and the use of specific encoding strategies to the achievement of a control group of similar students who were not provided with the same concrete mechanisms. The two groups were taught by the same instructor, who used the same teaching methods and identical class activities, homework, quizzes, and tests. The results indicated a statistically significant difference between the two groups, favoring the experimental group. Implications of the study for instruction and suggestions for further research are included. This study explored instructional capacity working memory that designs that encourage learners to consciously organizes information into become responsible for their own conceptual structures that make sense to learning. Responsible learners are the individual, a long-term memory that metacognitive, strategic, and high stores knowledge and skills in a achievers. Therefore, researchers have relatively permanent fashion, and become interested in investigating ways metacognitive monitoring that regulates to foster learners’ metacognition and this processing (Atkinson & Shiffrin, strategy use. 1968; Chandler & Sweller, 1990; Mayer The purpose of the study was to & Chandler, 2001; Paas, Renkl, & examine the impact of concrete Sweller, 2004; Sweller, 2003; Sweller, mechanisms for promoting van Merrienboer, & Paas, 1998). The metacognition and the conscious use of way knowledge is stored in long-term encoding strategies on the achievement memory has an important impact on of undergraduate educational learners’ ability to retrieve that psychology students.
    [Show full text]
  • The Benefits of Stimulus-Driven Attention for Working Memory
    Journal of Memory and Language 69 (2013) 384–396 Contents lists available at SciVerse ScienceDirect Journal of Memory and Language journal homepage: www.elsevier.com/locate/jml The benefits of stimulus-driven attention for working memory encoding ⇑ Susan M. Ravizza a, , Eliot Hazeltine b a Department of Psychology, Michigan State University, United States b Department of Psychology, University of Iowa, United States article info abstract Article history: The present study investigates how stimulus-driven attention to relevant information Received 18 July 2012 affects working memory performance. In three experiments, we examine whether stimu- revision received 30 May 2013 lus-driven attention to items can improve retention of these items in working memory. Available online 22 June 2013 Lists of phonologically-similar and dissimilar items were presented at expected or unex- pected locations in Experiment 1. When stimulus-driven attention was captured by items Keywords: presented at unexpected locations, similar items were better remembered than similar Verbal working memory items that appeared at expected locations. These results were replicated in Experiment 2 Attentional capture using contingent capture to boost stimulus-driven attention to similar items. Experiment Short term memory 3 demonstrated that stimulus-driven attention was beneficial for both similar and dissim- ilar items when the latter condition was made more difficult. Together, these experiments demonstrate that stimulus-driven attention to relevant information is one mechanism by which encoding can be facilitated. Ó 2013 Elsevier Inc. All rights reserved. Introduction strated in research examining the detrimental effects on WM performance when stimulus-driven attention is cap- Working memory (WM) keeps information in an active tured by irrelevant distractors (Anticevic, Repovs, Shul- state for a short period of time so that it can be readily ac- man, & Barch, 2009; Majerus et al., 2012; Olesen, cessed and manipulated in the service of immediate task Macoveanu, Tegner, & Klingberg, 2007; West, 1999).
    [Show full text]
  • Encoding Time and Allocation of Attention in Analogical Development
    Encoding time and allocation of attention in analogical development Nina Simms ([email protected]) Department of Psychology, 2029 Sheridan Road Evanston, IL 60202 USA Dedre Gentner ([email protected]) Department of Psychology, 2029 Sheridan Road Evanston, IL 60202 USA Abstract become increasingly adept at reasoning on the basis of relational rather than object similarity (Gentner & The aim of the current studies was to explore encoding time differences in objects and relations and to investigate whether Rattermann, 1991). these differences lead to differences in allocation of attention For example, Gentner and Toupin (1986) gave 6-year-old to object similarity. Using a match-to-sample paradigm with children a simple story and asked them to reenact it with 5- to 6-year-olds and adults, we found that (1) objects were new characters. They performed well when the encoded faster than relations for both adults and children, and corresponding characters were highly similar between the that (2) children, but not adults, preferentially allocated two stories, but performed very badly when similar attention to object similarity. Ultimately, these questions are characters played different roles across the two stories (the aimed at identifying the factors responsible for the cross-mapped condition). Further studies have corroborated development of adult-like analogical reasoning. We suggest this finding that when relational similarity is pitted against that changes in selective attention over development may account for the pattern of results seen across these two object similarity children tend to be highly influenced by studies. object matches and less able to attend to relational matches. For example, Richland and colleagues (2006) found the Keywords: analogical development; relational reasoning; same pattern of results in a picture-matching task.
    [Show full text]
  • Memory Formation, Consolidation and Transformation
    Neuroscience and Biobehavioral Reviews 36 (2012) 1640–1645 Contents lists available at SciVerse ScienceDirect Neuroscience and Biobehavioral Reviews journa l homepage: www.elsevier.com/locate/neubiorev Review Memory formation, consolidation and transformation a,∗ b a a L. Nadel , A. Hupbach , R. Gomez , K. Newman-Smith a Department of Psychology, University of Arizona, United States b Department of Psychology, Lehigh University, United States a r t i c l e i n f o a b s t r a c t Article history: Memory formation is a highly dynamic process. In this review we discuss traditional views of memory Received 29 August 2011 and offer some ideas about the nature of memory formation and transformation. We argue that memory Received in revised form 20 February 2012 traces are transformed over time in a number of ways, but that understanding these transformations Accepted 2 March 2012 requires careful analysis of the various representations and linkages that result from an experience. These transformations can involve: (1) the selective strengthening of only some, but not all, traces as a function Keywords: of synaptic rescaling, or some other process that can result in selective survival of some traces; (2) the Memory consolidation integration (or assimilation) of new information into existing knowledge stores; (3) the establishment Transformation Reconsolidation of new linkages within existing knowledge stores; and (4) the up-dating of an existing episodic memory. We relate these ideas to our own work on reconsolidation to provide some grounding to our speculations that we hope will spark some new thinking in an area that is in need of transformation.
    [Show full text]
  • Encoding Processes for Recall and Recognition: the Effect of Instructions and Auxiliary Task Performance
    Bulletin of the Psychonomic Society 1977, Vol. 9 (2),127·130 Encoding processes for recall and recognition: The effect of instructions and auxiliary task performance STEPHEN A. MAISTO. RICHARD J. DeWAARD. and MARILYN E. MILLER University of Wisconsin. Milwaukee, Wisconsin 59201 The present experiment investigated the hypothesis that encoding for recall involves organization of input stimuli. while recognition entails encoding to achieve discriminability of individual items. Subjects were given either recall or recognition instructions. one or three presentations of a list of nouns, and did or did not perform an auxiliary task of repeating the words aloud at input. All subjects received recall and recognition tests. The results showed higher recall with recall instructions in the no-task condition. Oral repetition produced a decrement in recall following recall instructions, but had no effect with recognition instructions. Also, the auxiliary task had no effect on recall with recognition instructions, but with recog­ nition instructions recognition performance was increased to the level of recall subjects. The results are discussed in terms of current models of recall and recognition. In accounting for free recall performance, models encoding of that item" (Tversky, 1973, p. 285). of recall and recognition have incorporated the However, if retrieval processes are important for finding that organization (i.e., forming associations recognition, then there should be much overlap in among items) of target items is positively related to how information is encoded following instructions for efficient retrieval of those items from memory recall and recognition tests. (Klatzky. 1975). However, models of recall and Several researchers have examined encoding differ­ recognition can be distinguished on the basis of the ences in recall and recognition.
    [Show full text]
  • Cognitive Functions of the Brain: Perception, Attention and Memory
    IFM LAB TUTORIAL SERIES # 6, COPYRIGHT c IFM LAB Cognitive Functions of the Brain: Perception, Attention and Memory Jiawei Zhang [email protected] Founder and Director Information Fusion and Mining Laboratory (First Version: May 2019; Revision: May 2019.) Abstract This is a follow-up tutorial article of [17] and [16], in this paper, we will introduce several important cognitive functions of the brain. Brain cognitive functions are the mental processes that allow us to receive, select, store, transform, develop, and recover information that we've received from external stimuli. This process allows us to understand and to relate to the world more effectively. Cognitive functions are brain-based skills we need to carry out any task from the simplest to the most complex. They are related with the mechanisms of how we learn, remember, problem-solve, and pay attention, etc. To be more specific, in this paper, we will talk about the perception, attention and memory functions of the human brain. Several other brain cognitive functions, e.g., arousal, decision making, natural language, motor coordination, planning, problem solving and thinking, will be added to this paper in the later versions, respectively. Many of the materials used in this paper are from wikipedia and several other neuroscience introductory articles, which will be properly cited in this paper. This is the last of the three tutorial articles about the brain. The readers are suggested to read this paper after the previous two tutorial articles on brain structure and functions [17] as well as the brain basic neural units [16]. Keywords: The Brain; Cognitive Function; Consciousness; Attention; Learning; Memory Contents 1 Introduction 2 2 Perception 3 2.1 Detailed Process of Perception .
    [Show full text]
  • Encoding Processes in Recognition and Recall
    COGNITIVE PSYCHOLOGY 5, 275-287 (1973) Encoding Processes in Recognition and Recall BARBARA TVERSKY~ Hebrew University The present experiments demonstrate that picture-word stimuli are differentially encoded in anticipation of a recognition test than in anticipa- tion of a free-recall test. Subjects perform better on the retention test of which they have been informed, and different information from the stimuli is used to pass each test. These findings cannot be attributed to stimulus selection nor to pure pictorial encoding in anticipation of recognition and pure verbal encoding in anticipation of recall. Recognition is enhanced by encoding which integrates the details within each item while recall is enhanced by encoding which interrelates the items of a list. The superiority of recognition tests of memory to recall tests has typically been attributed to the fact that less information about an item is needed to pass a recognition test (Postman, 1963). Partial learning may be sufficient to choose the correct alternative or reject an incorrect alternative in a recognition test, but not enough to guarantee correct recall. Recently, several theorists, notably Estes and Da Polito ( 1967), Kintsch ( 1970)) Bahrick ( 1970), and Anderson and Bower ( 1972)) have proposed that an important difference between recognition and recall tests of memory is that the former by-pass the retrieval stage of memory necessary in recall. Since the correct alternative is presented in the recognition test, S presumably does not have to search his memory to find it. To support his contention, Kintsch ( 1970) reviewed and reported data on variables which have different effects on recognition and recall tests of memory.
    [Show full text]
  • A Review of Theories of Human Amnesia LEONARD D
    Memory & Cognition 1981, Vol. 9 (3),247-262 A review of theories of human amnesia LEONARD D. STERN University ofOregon, Eugene, Oregon 97403 Six theories of human amnesia are examined. Each is categorized according to the processing ability that is conceived to underlie the amnesic deficit. The theories fall into one of four categories: consolidation, retrieval, semantic encoding, and context encoding deficit theories. The recently proposed context encoding deficit theories are found to offer the most satis­ factory account of the human amnesic syndrome. It is suggested that the other theoretical approaches are best viewed as special cases of these context encoding deficit theories. The human amnesic syndrome is characterized by a technique in the treatment of psychosis. This surgical severely impaired memory for day-to-day events procedure, used as an alternative to a complete frontal accompanied by normal intelligence, perceptual abilities, lobotomy, was intended to avoid the side effects that and other cognitive functions. Amnesia is typically the lobotomy normally produced (B. Milner, 1966). associated with brain trauma brought about by blows to After 30 of these operations had been performed, it was the head, surgical removal of portions of the brain, or discovered that a serious memory impairment could degenerative processes that accompany excessive and result. Memory deficits were initially discovered in two prolonged alcohol consumption (Korsakoff's syndrome). of Scoville's patients. One patient had undergone surgery The focus of this paper will be on theoretical accounts to treat a psychosis, and the other, the well-known H.M., of the human amnesic syndrome. The theories of amnesia had undergone surgery to control epileptic seizures.
    [Show full text]
  • Models of Memory
    To be published in H. Pashler & D. Medin (Eds.), Stevens’ Handbook of Experimental Psychology, Third Edition, Volume 2: Memory and Cognitive Processes. New York: John Wiley & Sons, Inc.. MODELS OF MEMORY Jeroen G.W. Raaijmakers Richard M. Shiffrin University of Amsterdam Indiana University Introduction Sciences tend to evolve in a direction that introduces greater emphasis on formal theorizing. Psychology generally, and the study of memory in particular, have followed this prescription: The memory field has seen a continuing introduction of mathematical and formal computer simulation models, today reaching the point where modeling is an integral part of the field rather than an esoteric newcomer. Thus anything resembling a comprehensive treatment of memory models would in effect turn into a review of the field of memory research, and considerably exceed the scope of this chapter. We shall deal with this problem by covering selected approaches that introduce some of the main themes that have characterized model development. This selective coverage will emphasize our own work perhaps somewhat more than would have been the case for other authors, but we are far more familiar with our models than some of the alternatives, and we believe they provide good examples of the themes that we wish to highlight. The earliest attempts to apply mathematical modeling to memory probably date back to the late 19th century when pioneers such as Ebbinghaus and Thorndike started to collect empirical data on learning and memory. Given the obvious regularities of learning and forgetting curves, it is not surprising that the question was asked whether these regularities could be captured by mathematical functions.
    [Show full text]