Key points for lecture 4

• Forgetting: good or bad?

• How does the Deese / Roediger / McDermott (DRM) paradigm work?

• Which factors increase or decrease false memory?

• What are the actual underlying (cognitive) causes of false memory?

• Reisberg, Chapter 7.

When Memories Go Wrong

• What happens when your memory of an event does not correspond to what actually happened?

– In what ways can our decisions get warped by an inaccurate memory?

– Are we always aware when this happens?

Forgetting

• Is Normal!

• And desirable!

• The Case of “S” (Luria, 1968)

The Case of “S”

• “S” did not benefit a great deal from having a ‘perfect’ memory.

– Impaired ability to abstract general knowledge from his experiences.

– Related to his inability to forget specific details of each event?

– Almost the opposite of Varga-Khadem’s amnesic children.

Episodic vs. Semantic Memory

• Baddeley’s Metaphor

• Our general knowledge is represented in a distinct ‘semantic’ Memory

Episodic & Semantic Components of Autobiographical Memory

• Parker et al. (2006), Neurocase 12: pages 35-39. (pdf available via my webpages)

• Case A.J. : ‘…highly superior semantic autobiographical memory’

Sources of Error in Normal Memory

• Forgetting.– A natural feature of our memory?

• Recollection and familiarity may have to trade off against one another all the time.

– How might their interaction distort our memory of the past, and mislead our judgement?

The Weight of Eyewitness Evidence

• An estimated 77,000 people annually in the USA are charged solely on the basis of eye witness evidence.

• Around three quarters of English cases result in conviction due to eye witness testimony (of which half were based on a single eye witness).

Introducing Distortions into Memory

• Force subjects to experience very similar kinds of episodes, which become hard to discriminate from one another

• Manipulating the familiarity of retrieval cues

The Deese (1959) Recall Task– QUEEN– ENGLAND– CROWN– PRINCE– GEORGE– DICTATOR– PALACE– THRONE– CHESS– RULE– SUBJECTS– MONARCH– ROYAL– LEADER– REIGN

– SOUR

– CANDY

– SUGAR

– BITTER

– GOOD

– TASTE

– TOOTH

– NICE

– HONEY

– SODA

– CHOCOLATE

– HEART

– CAKE

– TART

– PIE

The Deese (1959) Recall Task

• Deese constructed his lists using word association norms.

• Each item in a list is a strong associate of a particular TARGET word.

• Deese found high levels of recall intrusions by these unpresented TARGET items.

Roediger and McDermott (1995)

• Modified and extended Deese’s basic result.

– Employing recall and recognition tasks– Use of the Remember / Know (R/K) procedure.

The Remember / Know Procedure

• 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?

Recognition Test List– PLACE

– SWEET

– TABLE

– PARTY

– GENERAL

– MEMORY

– CONSENSUS

– KING

– COMPUTER

– TREE

– FERRET

– BURGLAR

– BOTTLE

Roediger and McDermott (1995)

• Percent Recognition

0

10

20

30

40

50

60

70

80

90

OVERALL REMEMBER KNOW

TRUEFALSE

Some Factors that increase or decrease DRM False Memory

• Increase: the number of associates presented for study

• Increase: the strength of association between study list items and their TARGET

• Decrease: (in young people) multiple study-test cycle.

• Decrease: the ‘distinctiveness heuristic’

‘Distinctiveness Heuristic’

• Two study conditions– Words from the DRM lists– Words from the DRM lists paired with a picture

• False recognition was almost absent when words had been paired with pictures

• The ability to recollect picture information was ‘diagnostic’ for studied items.

–

A triple whammy!3 Reasons for ‘DRM’ False Memory

(1) Implicit associative responses– subjects themselves generate the target items while

studying each list.– Then experience ‘source confusions’ at test

(2) Familiarity of ‘lure’ items– But what about the ‘Remember’ responses?

(3) A loss of encoding specificity

The puzzle raised by false memory

• Within the consensus view, how is it possible to recollect events that never took place?

• That is, what might causeSource errors?Familiarity-based confusions?Loss of encoding specificity?

CMF Explanations for DRM False Memory

• The hippocampal formation Pattern separation failure at encoding Pattern completion failures at retrieval Therefore: source errors, & loss of encoding specificity

• The frontal lobes Strategic control over memory Failure to adequately focus on cues and/or monitor retrieval

• The entire ‘association’ neocortex Represents very similar content across a succession of episodes

Summary

• Judgements are most accurate when they are made on the basis of information whose source has been recollected.

• But if retrieval instructions allow it, judgements may be based, by default, upon potentially less accurate familiarity.

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