Chapter 7 - Human Memory: Conceptual Approaches

PSY 445: Learning & Memory

Processes involved in retaining, retrieving, and using information about stimuli, images, events, ideas, and skills after the original information is no longer presentThree theoretical approaches to memory Memory componentsDifferent types of memoryStages of memorySeries of steps are involved in memory processProcesses of memory Emphasis is on how memories are processed

Why do we think there are multiple memory systems?General principles differ for STM and LTMHeuristic value – guideline that is fairly accurateEmpirical evidence supporting the existence of multiple processes

Dissociation – occurs when an experimental variable has different effects on different tasks

Double dissociation – experimental variables differentially affect performance on two or more tasks

Kesner, Hopkins, & Chiba (1992)ProcedureGroup 1: Left-hemisphere brain damageGroup 2: Right-hemisphere brain damage

Words or an X was flashed on a screen Participants were asked to recall the word and the

location of the XResultsGroup 1 did worse on the word-recognition test; Group 2 did worse on the spatial-location testInterpretationThe two cerebral hemispheres are playing different roles in verbal and spatial learning; double dissociation

Dual-Store TheoryShort-Term Memory Long-term memory

Atkinson & Shiffrin (1968)

A limited capacity memory system involved in the retention of information for brief periods; it is also used to hold information retrieved from long-term memory for temporary useDuration of STMWithout maintenance rehearsal something stays in STM for between 15-30 secondsCapacity of STMAbout 7 items

Differences in capacity STM is relatively small and easily measured LTM is immeasurable and probably limitless

Differences in duration STM can hold only items briefly LTM are relatively permanent; not affected

by the passage of time much Evidence for the STM vs. LTM Distinction

Serial-position curve results

Explicit memory Is long-term memory for factual knowledge and personal experiences and requires conscious recall

Two types of explicit memories:Episodic memories are memories for personal life experiences (e.g., your senior prom night)Semantic memories are memories for factual knowledge that is true of everyone (e.g., the current President of the United States)

Testing Episodic and Semantic MemoriesLimitationsIt is difficult to differentiate episodic and semantic memories in lab testsThe two forms of memory require different testing materials, procedures, or tasksWord-frequency effect is an example of this

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ProcedureGroup 1: given a test of episodic memory High-frequency and low frequency words are presented to participants; later, word recognition testGroup 2: given a test of semantic memoryHigh-frequency and low frequency words are presented to participants; later strings of letters are briefly flashed on the screen; task is to decide which strings form real words and which do not

Results Group 1: More low-frequency words from original list are recognized; this paradoxical result is referred to as the Word-Frequency EffectGroup 2: More high-frequency words from original list are recognizedInterpretationConfounding of the type of test with the type of memoryNot necessarily testing episodic vs. semantic processes but rather recognition memory vs. identification memory

Implicit memory •Long-term memory that influences our behavior, but does not require conscious awareness or declarative statements (e.g., for most adults, driving a car; walking)•Procedural memory is a type of implicit memory

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The acquisition of knowledge of how to do things and includes perceptual skills, motor skills, and cognitive skillsMemory for highly practiced skills (often referred to as skill memory)Bike-riding, Shoe-tyingAutomatic or implicit nature to it (implicit memory)Do you think about reading a book?Do you think about riding your bike?

Mirror drawing

The facilitated response to a stimulus that has been recently experienced Occurs when the test stimulus is the same as or resembles the priming stimulusThe initial presentation of a stimulus affects subsequent presentations

Rajaram & Roediger (1993)ProcedureWord completion testPhase 1: Present priming stimuli

• Example: tablePhase 2: Open-ended recall

• Example: Complete this word: tab___Results Primed participants (49%) are more likely than non-primed participants (30%) to use a particular wordInterpretationParticipants responses are manipulated by implicit processes

Warrington & Weiskrantz (1968)ProcedureParticipants are patients with Korsakoff’s syndrome (cannot form new LTMs); Researchers trained them to identify incomplete pictures

Subjects never remembered their previous days of training

ResultsPerformance improves even though the person does not remember being trained

InterpretationPriming can occur with pictorial stimuli as well; previous experiences affect current behavior without awareness

Results

Warrington & Weiskrantz (1968)

3 stages of processing for manipulation of mental representations:

Encoding (acquisition of info)Storage (retention of info)Retrieval (recovery of info)

time

Encoding/Failure Retrieval? (LTM)STM Retention

Dissociating StagesExperimentalNeuropsychological

Experimental manipulations often detect functional dissociations of the stagesEncoding, storage, or retrieval may be affected differentlyDifferent things are involved depending on the stage of memory

Storm & Caird (1967): Experiment 1ProcedureAlcoholic inpatients were given lists to learn either while sober or after consuming alcohol; both groups tested later in sober state (two groups: S/S, A/S)ResultsS/S outperforms A/SInterpretationAlcohol impaired encoding However, alternative explanation is performance is related to state-dependent retrieval

Storm & Caird (1967): Experiment 2ProcedureTwo more groups were added (total of four groups now)

Studied sober and tested when drinking alcohol (S/A) Studied when drinking alcohol and tested while

drinking alcohol (A/A)

ResultsS/S > A/A

InterpretationMore than just retrieval failure; due to impaired encoding

Neuropsychologists attempt to dissociate certain stages by finding individuals with impairment at one stage or another

Hippocampus: brain structure plays a key role in allowing us to store new informationThe classic case of H.M. who had this part of brain removedIn 2008 (at the time of his death at age 82), was his name revealed as Henry Molaison

From neuropsychological dissociation view, H.M.’s problem could be explained in several ways: Encoding deficit Storage deficit (encoding okay) Retrieval deficit (encoding and storage okay)

Craik & Lockhart (1972)A single memory system is hypothesizedRapid forgetting is due not to a loss from transient STM but rather because of shallow processingRetention is due not to transfer from one memory store to another, but rather to deeper processing

How does storage of information take place?

Maintenance Rehearsal▪ Repeating things over and over▪ Spacing effect

Elaborate Rehearsal▪ Involves thinking about how new material

relates to information already stored in memory

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Shallow Processing Little attention to meaning Focus on physical features of the word

(number of vowels, letters in all capitals) Occurs during maintenance rehearsal

Deep Processing Close attention to meaning Relating item to something else

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Craik & Tulving (1975)

Recall Test was a surprise to participants

Procedure

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ProcedureTypes of questionsShallow:

Is the word printed in capital letters?Deeper:

Does the word rhyme with train?Deepest:

Does the word fit into the sentence “He saw a ____ on the street?”

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• Deep processing takes longer but results in better memory

Shallow:

Deeper:

Deepest:

Craik & Tulving (1975)Results

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InterpretationMemory for words is better when they are linked to other knowledge

Craik & Tulving (1975)

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Depletion of Memory CapacityWhen participants are attempting to perform two cognitive tasks at once, (for example, doing math calculations and remembering words), if the primary task requires deeper processing, this leaves little left over for the other taskDeeper processing on the first task is shown by poor performance on the second taskSemantics IssueThe term “depth” appears to be taking on different meaningsElaboration of an item in memory or more distinctive representation in memory

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Morris, Bransford, & Franks (1977)Similarity between encoding and retrieval conditionsDuring retrieval, we need to reinstate the cognitive operations that were used at encoding

Explicit memory: match mental operations of encoding and retrievalImplicit memory: match perceptual operations at encoding and retrieval

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Weldon & Roediger (1987)ProcedurePhase 1:Students studied lists of both pictures and wordsPhase 2: Either a picture fragment or word-completion test was givenTask for both groups was to name the picture or word

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Weldon & Roediger (1987)ResultsStudying pictures produced more priming than did words on a picture-fragment test; studying words produced more priming than did pictures on the word-fragment test

Results

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InterpretationTransfer-appropriate processing was necessary for optimal recall to occur

Picture-fragment test: inspecting a picture is similar at both encoding and at retrieval; dissimilar to word-readingWord-fragment test: Reading words is a cognitive operation similar to completing words, but inspecting pictures is not

Simulate various memory phenomenon by using a network of hypothetical neuronsAttempt to statistically model the nervous system on a computerEach neural unit can potentially have connections to many other units; the more connections the better memory

Modeling Person IdentificationMany possible connection between names and identities

For example, John has a connection to several potential features

The Delta RuleConnections can vary in strengthMathematical formula used for increases and decreases in strength

Classification of AmnesiasTwo dimensionsCause: physical or psychological (psychogenic amnesia)Time: loss of memory preceding (retrograde) or following the trauma (anterograde)Retrograde amnesia•Loss of memory for events that have happened prior to trauma or diseaseAnterograde amnesiaThe inability to form long-term memories for events following brain surgery or trauma

Retrograde amnesia—TRAUMA—Anterograde amnesia

Amnesias caused by psychological traumas are almost retrograde Psychogenic Amnesia3 main categories:Limited AmnesiaForgetting of a specific traumatic experienceFugue stateLoss of one’s entire past life and identity; often travel away from homeDissociation DisorderA person exhibits multiple personalities or identities

ABC News Poll (1997) 46% more worried about failing memory than failing health

Plethora of self-help books, websites, and herbal medicationsMost worry is unjustified

Some of the slides in this presentation prepared with the assistance of the following website:www.csupomona.edu/.../PSY335%20PPTs/Baddeley/BChap6....