Section 5. Memory 1. What is memory? memory subsystems memory processes 2. Memory subsystems sensory memory short-term (working) memory long-term memory 3. Memory processes levels of processing theory remembering amnesic syndrome/LTM subsystems 4. Representation of information in memory analog vs. propositional representation concepts schema 5. Mnemonics Terms to know for this section Readings Reisberg - pp. 123-167 (memory structures), 168-210 (memory processes), 394-439 (visual memory), 256-303 (theories of memory organization), 304-345 (concepts), 211-255 (memory problems) 5.1 What is memory? Functional definition: Memory is the retention of potentially usable information over some period of time. Memory subsystems - organization of memory into component parts sensory memory short-term memory long-term memory Memory processes - the activities that occur in memory control encoding - transduction storage retrieval - relationship to encoding 5.2 Memory subsystems The spatial metaphor for memory - items in memory are like objects located in a space that must be searched for retrieval to take place. Problem - If we search memory to retrieve information, why is it sometimes so easy to say that we don't know something? (Would it not be necessary to search everywhere in memory to confirm that we did not know something?) Characteristics of memory subsystems - capacity - how much information? duration -how long does the information last? representation - what kind of information is retained? information loss - how does forgetting occur? decay/interference (retrieval failure) The modal (3-store) model of memory (Atkinson & Shiffrin, 1968) 5.2 continued 1. Sensory memory high capacity short duration uncoded, precategorical representation information loss through interference sensory-specific Sperling' s (1960) experiments - visual sensory memory - iconic memory 5.2 continued 2. Short-term memory (STM) limited capacity - 7+2 chunks (Miller, 1956) short duration - limited by rehearsal? visual/auditory/etc. codes information loss through interference interaction between sensory information and information from long-term memory chunk - a meaningful unit of information e.g., 855-4267 855-1300 855-9668 339-4655 443-7855 758-2246 565-7421 visual STM (deGroot, 1965) - expert vs. novice chess players phonological STM - Conrad (1964) - visual letter confusions are phonological 5.2 continued 3. Long-term memory (LTM) unlimited capacity? unlimited duration? abstract, highly-organized representation information loss due to retrieval failure importance of rehearsal Evidence for the distinction between STM & LTM: Recall task; stimuli = lists of words interference task / rate of presentation manipulation serial position curve primacy effect recency effect Control processes - rehearsal, encoding, etc. Rundus & Atkinson (1970) - Rehearsal processes in free recall: A procedure for direct observation Rehearsal was the primary mechanism considered for the transfer of information from STM to LTM within the context of the modal model. Rundus & Atkinson utilized a verbal protocol in which subjects spoke aloud while learning a list of words that were to be recalled later. They showed that items from the beginning of the list received more rehearsals than items from later in the list. Except for items at the end of the list, the number of rehearsals was correlated with the number of words recalled. 5.2 continued Criticisms of the modal model - over-simplified - suggested that STM and LTM were each unitary memory stores role of rehearsal exaggerated Revisions to the modal model - Working memory (Baddeley & Hitch, 1974; Baddeley, 1986) augmented version of STM (based, in part, on neuropsychological evidence) - modality-free central executive articulatory loop (phonological store + articulatory production memory) visual-spatial sketch pad 5.3 Memory processes Alternatives to the modal model assume a unitary store that is equivalent to LTM and in which STM is equivalent to temporarily activated regions of LTM. Thus, this type of model uses an activation metaphor. In addition, less emphasis is placed on rehearsal as a mechanism for adding information to LTM. As an alternative, more emphasis is placed on how subjects encode information. 5.3 continued 1. How does the type of encoding affect the retrieval of information? levels of processing theory (Craik & Lockhart, 1972) the level or depth of processing of information affects its memorability deep processing creates more robust memories than shallow processing shallow processing - Is the word in capital letters? table/TABLE deep processing - Would the word fit in the sentence? "He met a ___ on the street." FRIEND/cloud In general, recognition memory performance was best (80%) for words that received deep processing whereas performance was worst (20%) for words that received shallow processing. Problems with levels of processing theory - what level of processing does the orienting task utilize? How can depth be assessed independently of memory performance? relation between orienting task and memory task (Morris, Bransford, & Franks, 1977 - semantic/rhyme encoding task; standard/rhyme recognition tasks). 5.3 continued 2. What happens when we remember something? 1. Retrieval cues retrieval of information is based on the concept of retrieval cues What is a retrieval cue? …anything that could serve to activate relevant or associated information in memory Sometimes the cues are supplied to you, as in a recognition memory task (such as multiple choice exam). In that case, in that case you are assumed to require only some type of decision process to evaluate the information evoked by the cues. Alternatively, you have to supply the cues yourself, as in a recall task (such in an essay exam). Here you must supply both retirival cues and evaluate the relevance of the information evoked. 2. Encoding specificity principle (Tulving, 1982) the similarity between the information available at the time of encoding and the time of retrieval determines memory performance +similarity(encoding; retrieval) —> +memory state-dependent learning (mood / drugs) physical context (Godden & Baddeley, 1975) - wet vs. dry learning, wet vs. dry testing 3. Limits on the use of recall and recognition task (knowledge=experience=behaviour) doctrine of concordance (Tulving, 1989) Tacit assumption of many memory researchers that generally there is similarity "…between what people know, how they behave and what they experience. Thus conscious awareness is required for, and therefore accompanies, the acquisition of knowledge, or its retrieval from the memory store; retrieved knowledge guides behaviour, and when this happens, people are aware of the relation between the knowledge and the behaviour." 5.3 continued 3. Amnesia and LTM subsystems Evidence from cognitive neuropsychology may be useful when considering memory structures and processes. Background information… syndrome - a group of symptoms that collectively characterize a specific condition or disease amnesic syndrome (source - Korsakoff' s syndrome, head injuries, & strokes) - anterograde amnesia generally present (a lack of memory for events after the trauma) - retrograde amnesia sometimes present (a lack of memory for events before the trauma) - amnesics generally have normal intelligence - generally intact STM - patients can usually learn certain things after the onset of amnesia What abilities do amnesics retain? (residual learning capacity) most have good STM performance most can learn to do tasks involving motor skills (but may be slower learning than normals). Patient H.M. & broken drawings amnesics are susceptible to perceptual priming (repetition priming) - conscious awareness vs. performance Theories of amnesia and memory must account for the abilities that amnesics have lost and those that they retain. 5.3 continued Theories of amnesia and memory must account for these effects. Theories of memory and amnesia 1. episodic vs. semantic memory (Tulving, 1972) episodic memory - contextual memory (autobiographical knowledge) semantic memory - factual knowledge that is independent of the setting in which it was originally learned Originally, amnesics were believed to have an impaired episodic memory system but an intact semantic memory system. Are episodic & semantic memory really two separate memory processes? Probably not. Amnesics usually exhibit intact episodic and semantic memory for events learned prior to their amnesia. 2. declarative vs. procedural memory (Cohen & Squire, 1980) declarative memory - "knowing what"; includes episodic and semantic memory procedural memory - "knowing how"; performance of skilled actions that do not require conscious awareness of recollection Cohen & Squire (1980) argue that amnesics have an impaired declarative memory but an intact procedural memory. However, 1) some amnesics are able to acquire declarative knowledge, 2) most tasks incorporate a mix of declarative and procedural memory. 3. explicit vs. implicit memory (Schacter, 1987) explicit memory - information available to conscious recollection implicit memory - information unavailable to conscious recollection; not usually tested in traditional measures of memory Support from experiments - compare recall/recognition w/ word fragment completion/perceptual performance normals (Jacoby & Dallas, 1981) amnesics - performance is often close to normal in implicit memory tasks whereas performance is generally worse than normal in explicit memory tasks Problems descriptive rather than explanatory Conclusion? No one theory of memory accounts for all aspects of memory performance in amnesics and non amnesics. Nor is it likely that memory can be neatly dichotomized as in these theories. Instead, memory is more like a series of integrated systems that contains some of the characteristics of the theories described here. 4. Representation of information in memory Basic questions What is a representation? In what form is information represented in memory? How is information organized so it can be efficiently used? A representation re-presents or stands for something. It is a transformation of information in one form to another form that preserves characteristics of the original information. Understanding the representation and processing of information are the two basic goals of cognitive psychology. Fundamental characteristic of all representational systems - there is less information contained in the representation than in the thing being represented. Internal representations (Mental representations) Propositions Analog 1. Discrete symbols 1. No discrete symbols 2. Explicit, needs symbol for relation 2. Implicit, no separate symbol for relation 3. Clear rules of combination for types of 3. No clear rules of combination or symbol symbol types 4. Abstract 4. Modality-specific 5.4 continued Propositions vs. imagery Imagery - analog representation based on visual information; manipulation of visual information mental rotation (Shepard et al.) image scanning (Kosslyn et al.) Propositions - a language-like representation of an event. e.g., predicate calculus Predicate (arguments); e.g., ON(BOOK, TABLE) Does one form of representation have priority over other forms? Can one form of representation be reduced to another form? Pylyshyn' s criticisms of imagery Images can' t just be 'pictures in the mind' s eye.' e.g., If an image has a missing part, it is usually a meaningful part that is missing. This is not necessarily true of a picture. If the 'mind' s eye' perceives images, what kind of images does it use? …an infinite regression. Images can be reduced to propositions. (images ® propositions) Results from imagery experiments are due to demand characteristics. Kosslyn' s response The idea that images are the same as pictures is a 'straw man' . Propositional accounts of image data are cumbersome. Images have distinct characteristics that make them different from propositional representations. Kosslyn' s theory/model of imagery 1. images are represented in a special spatial medium that has the following characteristics limited extent of medium area of highest resolution at centre medium has 'grain' that obscures fine detail in small images once an image is generated it begins to fade 2. Imaginal information is often linked to corresponding propositional information. 3. Generating images involves both imaginal and propositional information. Evidence for Kosslyn' s theory/model experimental - e.g., image tracing task (granularity) neuropsychological - e.g., dissociation between imaginal and propositional information 5.4 continued Concept organization Why do we have concepts? cognitive economy generalization (recognition of novel things ) recognition of the relationship among instances Theories of conceptual organization 1. Defining-attribute view (Classical view) Basically, a concept has defining attributes that determine the members of a concept. Defining attributes are also known as properties or features. the meaning of a concept is the conjunction of a set of attributes each attribute is singly necessary and jointly sufficient for an item to be considered a member of a concept explanation for singly necessary and jointly sufficient: singly necessary = each characteristic must be present for the object to belong to the category jointly sufficient = only these characteristics (and no others) are required for the object to be considered a member of the category example... definition of a bachelor - male, unmarried, adult Is Mr. Smith a bachelor age (beyond adulthood) unimportant size unimportant hair colour unimportant etc. clear-cut boundaries exist between items that are members of the concept and those that are not members all members of a concept are equally representative concepts are nested within superordinate concepts A model of the defining-attribute view Collins & Quillian (1969) semantic network hierarchical organization characteristics as defined above hierarchy is searched in response to inquiries about concept membership (search times are related to hierarchical distance) hierarchy is searched in response to inquiries about concept attributes (search times are related to hierarchical distance) Supporting evidence… sentence verification task "Is a canary a bird?"faster than "Is a canary an animal?" "Does a canary fly?"faster than "Does a canary have skin?" Problems with the defining-attribute view some attributes are more important for determining concept membership than others Feature listings for 2 concepts all members of a concept are not treated equally (typicality) Typicality ratings for birds (Rips, Shoben, & Smith, 1973) difficulty in determining the defining attributes of concepts (family resemblance?) Family resemblance analysis (Rosch & Mervis, 1975) concept membership is not always clear-cut (fuzzy boundaries) predictions based on the nesting of concepts are not always confirmed (e.g., "Is a chicken a bird?"vs. "Is a chicken an animal?") 5.4 continued 2. Prototype theory Designed to account for the problems associated with the defining attribute model, such as typicality effects and fuzzy concepts (compare with work on prototype theory in perception, section 4). What is a prototype? A representation that captures the central tendency of a set of similar items. It can be a) a summary description that is an abstraction of many instances, or b) a collection of the 'best instances' of a concept. there is no set of necessary and sufficient attributes concept boundaries are fuzzy instances are graded according to typicality concept membership is defined by similarity to the concept' s prototype Supporting evidence… apparent universality in the categorization of colours typicality ratings are good predictors of classification times typical concept members are listed first children generally learn about typical concept members first typical members tend to serve as cognitive reference points family resemblance scores can be calculated and typical members tend to have the highest scores Are some levels of abstraction in prototype theory more important than others? Rosch et al. (1976) specific objects - slotted screwdriver, Robertson screwdriver, Phillips screwdriver, etc. basic level - screwdriver superordinate level - tool Individuals tend to use basic level category terms. Tanaka & Taylor (1991) - Object categories and expertise: Is the basic level in the eye of the beholder? Problems with prototype theory not all concepts have prototype characteristics - deals best with concrete concepts, not abstract concepts does not incorporate information about the relationship among concepts (pets & fish; pet fish) does not account for the coherence of concepts - Why do members of a concept group together? It is not just similarity - we can form arbitrary concepts (women, fire, & dangerous things; things in a yard sale, etc.). 5.4 continued Schema How is information about individual concepts combined? How does the collective organization of information about individual concepts allow us to deal with everyday situations? schema - structured cluster of concepts (plural schemas or schemata); coined by Bartlett (1932) Early work on schema - Bartlett Subjects read story with non-Western construction (War of the Ghosts); recall story at later date. Subjects impose a Western organization on the information contained in the story. Subjects' recall was affected by their expectancies; memory was reconstructed according to past experiences. Characteristics of schema schema consist of relations, variables/slots, and values relations can be of the form 'is-a,' 'eat,' 'cause,' etc. variables contain other schema or concepts values are the instances that fit the variables schema contain general knowledge that can used in many specific situations (e.g., 'restaurant schema' ) slots may have default values Theories of schema organization Schank & Abelson' s script theory A script is a type of schema that describes the actions that are part of stereotypical events. e.g., restaurant script components specific actions entering walk into restaurant look for table decide seat location go to table sit down ordering get menu look at menu choose food server arrives order given to server order given to cook wait, talk! cook prepares food eating… leaving… script organization allows the efficient use of cognitive resources criticisms - unprincipled (ad hoc); inflexible 5.4 continued Implications of schematic/reconstructive processes for memory 1.gist vs. verbatim recall 2.John Dean' s memory 3.eye-witness testimony - Loftus 4.enhancing eye-witness testimony 5.4 continued 1. gist vs. verbatim recall gist = meaning verbatim = surface structure; exact wording in general, memory for gist is maintained while verbatim memory is lost Sachs (1967) He sent a letter about it to Galileo, the great Italian scientist. (test sentence) Galileo, the great Italian scientist, sent him a letter about it. (comparison sentence; different meaning) He sent Galileo, the great Italian scientist, a letter about it. (comparison sentence; same meaning, different word order) 5.4 continued 2. John Dean's memory who was John Dean? Richard Nixon' s counsel; Watergate Neisser (1981) compared what he remembered during the Watergate trial & Nixon' s tapes systematic distortions some of gist maintained - if information rehearsed in advance or repeated reflected Dean' s self-image (his recollection was that he played a more central role than he did in reality) gist preserved across episodes - underlying tone that permeated multiple encounters with the same people, discussing the same topics 5.4 continued 3. eye-witness testimony memory is subject to distortions that can occur at the time of encoding and distortions that can occur at the time of retrieval Loftus & Zanni (1975) - typical experiment show people film of vehicles involved in accidents test subjects: "Did you see a broken headlight?" vs. "Did you see the broken headlight?" (no broken headlight was shown in the film) results: those asked "Did you see the broken headlight?"were twice as likely to report that the headlight was broken. 5.4 continued 4. enhancing eye-witness testimony standard police interview open-ended questions - what happened? - short-answer questions about specifics Cognitive interview (Fisher & Geiselman, 1987) - increase overlap between encoding & retrieval; increase number of retrieval paths 1.mentally reinstating the environmental and personal context 2.reporting everything, regardless of the perceived importance 3.recount events in a variety of temporal orders 4.report events from a variety of perspectives (e.g., the witness and another significant figure in the event) General mnemonics: if you can' t remember a name, how many syllables, frequency of occurrence, ethnicity, etc. cognitive interview produces 25-35% more correct information than standard interview (also superior to other procedures, such as hypnosis). 5. Mnemonics PEMA - personal external memory aid Principles of mnemonics organization mediation imagery 1. Acronyms CHONSPX HOMES FACE EGBDF 2. Key word method foreign languages - link sound / meaning e.g., Russian: zronok (bell) - zero-oaks Atkinson (1975) 120 Russian words / 3 sessions control group retains 30% 6 weeks later key word method retains 45% 6 weeks later 3. method of loci Simonedes spatial locations 4. Peg word system ordering one is a bun ham two is a shoe broccoli three is a tree bananas ... ... ... ... ... ... ten is a hen apples You have reached the end of section 5.
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