Core Features of Episodic Memory l (1) Memory for specific events from your past l (2) Involves...

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Core Features of Episodic Memory (1) Memory for specific events from your past

(2) Involves retrieving the bound together contents and context (what happened, when it happened and where did it happen)

(3) Associated with a particular kind of conscious experience ‘mental time travel’ re-experiencing past sights, sounds, etc

Episodic Memory Mechanisms

ConsolidationMechanisms

AttentionalControl

Encoding Storage Retrieval

AttentionalControl

SemanticRecords

PerceptualRecords

Binding

ContextSemanticRecords

PerceptualRecords

Binding

Context

Aims of Lecture 3

(1) How the core features are investigated in lab-based experiments that strip EM down to its basic elements.

(2) How does EM differ from other forms of long term memory?

(3) What don’t we know about episodic memory?

Amnesia

Past Future

RetrogradeAnterograde

Vargha-Khadem et al, Science (1997)Three amnesic children

Beth: birth: perinatal anoxic episode, seizuresJon: age 4: seizuresKate: age 9: drug overdose, inducing seizures

Disabling memory problems with every-day lifeSpatio-temporal (i.e. Episodic!)

But ‘normal’ intellectual development

Childhood (Anterograde) Amnesia

(1) What kind of brain damage was present?

(2) What kind of memory has been lost?» Which cognitive processes are no longer functioning?

(3) What kind of memory is still intact?

Questions Asked by Varga-Khadem

Functional brain imaging to reveal brain damage

Standard neuropsychological tests of general intellectual and memory function to establish the clinical profile

Experimental Cognitive Tests of item and associative recognition

Methods Used by Varga-Khadem et al

Selective bilateral (left and right) atrophy of the hippocampal formation

Common Underlying Brain Damage

Speech, language, IQ, etc, all within normal range Immediate recall normal (intact short term working

memory) Delayed recall severely impaired

A clinical profile consistent with a dense and selective anterograde amnesia

Standard Neuropsychological Tests of Intellectual and Memory Functions

Item and associative recognition for

Nonwords (eg FLUNT)FacesNonword pairsFace pairsVoice-face pairsObject-place pairs

Experimental Cognitive Tests of Memory

Study Phase

Recognition Test Phase

Performance on theCognitive Tests of Memory

TYPE OF STUDY ITEM ITEMRECOGNITION

ASSOCIATIVERECOGNITION

Nonwords INTACT INTACTFaces INTACT INTACT

Object-place pairs --- IMPAIREDVoice-face pairs ---- IMPAIRED

Selective and generalised loss of episodic memory function» The episodic memory failure may reflect an

inability to bind (associate) qualitatively different kinds of information together.

Intact ability to recognise must be based on a non-episodic form of memory.

General Conclusions

Core Features of Episodic Memory

(1) Memory for specific events from your past

AttentionalControl

SemanticRecords

PerceptualRecords

Binding

PerceptualRecords

Binding

Context

Encoding Specificity

How are memory traces accessed by retrieval ‘cues’?» Introduced by Tulving and Thompson, in 1973.

The most effective ‘retrieval pathways’ reinstate processing that occurred when the target information was encountered.

How Encoding Specificity Works

From Fisher and Craik (1976) (see Reisberg, pp176-177)

» Subjects studied word-pairs – The encoding task emphasised a relationship based either on

meaning (‘CAT-DOG’) or on sound (‘CAT-HAT’)

» And performed ‘associative recall’ tasks– Can you recall a studied word associated with ‘CAT’?

– Can you recall a studied word sounding like ‘CAT’?

Fisher and Craik’s Findings

ENCODEMEANING

ENCODE SOUND

MEANING CUE

SOUND CUE

Various Encoding Specificity Effects

ENCODE ONLAND

ENCODEUNDERWATER

RETRIEVE ONLAND

RETRIEVEUNDERWATER

SAD ENCODING HAPPYENCODING

SAD RETRIEVAL

HAPPYRETRIEVAL

ENCODEMEANING

ENCODE SOUND

MEANING CUE

SOUND CUE

PLACEBOENCODING

DOPE ENCODING

PLACEBORETRIEVAL

DOPERETRIEVAL

Encoding Specificity

Memory performance is best when there is overlap in the conditions at encoding and retrieval.

Nothing is encoded in isolation, information is always encoded within a ‘context’, including» The external spatiotemporal context (time and place)

» Your internal thoughts and feelings while the information is processed.

AttentionalControl

SemanticRecords

PerceptualRecords

Binding

PerceptualRecords

Binding

Context

Core Features of Episodic Memory (1) Memory for specific events from your past

His face is familiar...

When episodic memory fails.....

HEY BUDDY,I MISSED YOUSO MUCH....

Recollection Contrasted With Familiarity

Only recollection, the retrieval of episodic details, can provide information about the ‘source’ of a memory.

Familiarity can arise for a number of reasons, and can support recognition judgements even when recollection fails - hence it can be prone to error.

It is possible that Varga-Khadem’s patients may have been utilising the familiarity of studied items as a basis for their intact recognitions.

Modified Recognition Procedures

Remember / Know Judgements» Ask subjects to report on their experiences while recognising.

» Do they ‘Remember’ any episodic details

» Or do they just ‘know’ the information was encountered at study.

These cognitive processes supporting remember and know responses are not identical. » E.g. only ‘remember’ responses are reduced when attention is

divided.

Core Features of Episodic Memory l (1) Memory for specific events from your past l (2) Involves...

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