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.

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

‘DRM’ False Memory Increases with the number of associates presented for study Increases with strength of association between study list items and their TARGET Decreases (in young people) with multiple study-test cycle.

Possible Explanations 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? –Accounts for false ‘know’ responses.

Newer Variants of the DRM Paradigm False memory effects found with pictures. Influence of the ‘retrieval orientation’ that test instructions produce. –New, New+related, Old+identical –forces subjects to recollect, familiarity is not sufficient. Picture + Word encoding effects.

Picture + Word Encoding Two study conditions –Words from the DRM lists –Words from the DRM lists paired with a picture False recognition with pairs was almost absent compared to words alone. The ability to recollect picture information was ‘diagnostic’ for studied items.

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. –