Memory IIReconstructive Memory ForgettingObserve this crime sceneWhat does a penny look like?Memory BiasesLabel distorts memory of objectsReconstructive nature of memoryEffect of Expectation on MemoryMisinformation EffectMisinformation EffectMisinformation EffectExplaining Misinformation EffectOverwriting Hypothesis seems unlikelyRelevance to Criminal Justice SystemTraditional LineupSequential LineupRecovery of Lost Memories?Recovered memory vs. False MemoryCan false memories be implanted?Imagination InflationFalse Memory in the LabResultsAccuracy and ConfidenceForgettingForgetting FunctionsWhy do we forget?ExampleExampleEvidence for Retrieval Induced ForgettingInhibitory processes in memory?Think-no-Think ParadigmMemory IIReconstructive MemoryForgettingObserve this crime sceneWhat does a penny look like?Memory Biases• Memory is better for meaningful significant features than for details of language or perception Æ gist is remembered better than detailLabel distorts memory of objectsCarmichael, Hogan, & Walter (1932)Reconstructive nature of memory• Memory is often side-effect of comprehension– details can be filled in or reconstructed• Constructive approach to memory:– Memory = actual events + knowledge, experiences, expectationsEffect of Expectation on MemoryA simple demonstration experimentI am going to show you a picture of a graduate student’s office. Just take a look at it for a whileNow write down all the things you can rememberPotential responses:ChairsDeskTableBoxesBottle of winePicnic basketBooksSkullBrewer & Treyens (1981): 30% of subjects (falsely) recalled that books were presentMisinformation Effect• Memory for event can be influenced by information given after the eventElizabeth LoftusMisinformation Effect• Subjects view a movie of a car accident• Different expressions used to describe car contact• Subjects estimate speed of a car at time of contactMisinformation EffectExplaining Misinformation Effect• Three hypotheses– Overwriting• misleading information alters the memory trace– Source confusion• Sometimes we misremember the source of a memory• Perhaps the memory of the question is confused with the memory of the visual scene– Misinformation acceptance• Ss. believe the information in the postevent is trueOverwriting Hypothesis seems unlikely• McCloskey and Zaragoza (1985)• See event: yield sign• Receive misinformation, “as the car passed the...”misleading: “...stop sign?”nonmisleading: “...yield sign?”• Test: yield sign OR stop sign Æ 35% drop in accuracy for misleading informationyield sign OR no U-turn Æ no difference in accuracy for misleading information(both groups much higher than chance)Relevance to Criminal Justice System• most obvious case–crime Æ study– picture of suspect (mugshot) Æ misinformation – Lineup Æ test• Eyewitness may recognize suspect from mugshot, not from crime scene.• Conclusions:– Do not let potential witnesses see suspects.– Interrogate without asking leading questionsTraditional Lineup1 2 3 45 6 7 8Sequential Lineup1 2 3 45 6 7 8Recovery of Lost Memories?• Several lawsuits have relied on eyewitness testimony of repressed memories. These memories were “recovered”by family member or therapist• Claim: repression follows stress, but repressed material can be returned to consciousness with the removal of stress (e.g., Zeller, 1950, 1951; Merrill, 1954)• Problem: • Are these repressed memories or false memories (based on misinformation)?Recovered memory vs. False Memory• How do we know whether repressed memories are accurate? Hard to falsify• In some cases, traumatic information is misremembered or simply “made up”– Loftus has been involved in many cases– Points out problems of • hypnosis• suggestive questioning• dream interpretationsCan false memories be implanted?Loftus and Pickrell (1995)Imagination InflationFalse Memory in the Lab• Deese, Roediger, McDermott paradigm• Study the following words• Recall test .... • Recognition memory testUse ratings 1) sure new 2) probably new 3) probably old 4) sure old• TEST: BEDRESTAWAKETIREDDREAMWAKESNOOZEBLANKETDOZESLUMBERSNORENAPPEACEYAWNDROWSYSNORERESTCOFFEESLEEPResults• Critical lure (“sleep”) are words not presented but similar to studied words. These words are often falsely recalled (sleep: 61% of Ss.)• Recognition memory resultsproportion of items classified with confidence levels:confidence rating 4 3 2 1studied items .75 .11 .09 .05not studiedunrelated .00 .02 .18 .80critical lure .58 .26 .08 .08(e.g. “REST”)(e.g. “COFFEE”)(e.g. “SLEEP”)Accuracy and Confidence• Eyewitness testimony requires accuracy and confidence– “eyewitness testimony is likely to be believed by jurors, especially when it is offered with a high level of confidence” (Loftus, 1979)– Should we rely on the confidence level given by a witness (“I am sure I saw this”)? – False memory experiment shows sometimes confidence is high while accuracy is lowForgettingForgetting Functions• Ebbinghaus (1885/1913): Forgetting over time as indexed by reduced savings. Most forgetting functions show:Negative accelerationRate of change gets smaller and smaller with delayPower law of forgettingWhy do we forget?Some possibilities:• Memory has disappeared Æ decay theory• Memory is still there but we can’t retrieve it Æ interference theorye.g. blockingÆ inhibitory mechanismse.g. retrieval induced forgettingsupressionExample• You call a friend, but realize you need an older phone number that you have not used for a while. With effort, you recall the correct old phone numberFRIENDNEW PHONENUMBEROLD PHONENUMBERExplanation 1: the old number is blocked by the new associationExample• You call a friend, but realize you need an older phone number that you have not used for a while. With effort, you recall the correct old phone numberFRIENDNEW PHONENUMBEROLD PHONENUMBERExplanation 2:the old memory has been suppressedÆ Retrieval induced forgettingEvidence for Retrieval Induced Forgetting• Blocking would predict that using a new cue would remove blocking effect. Suppression would predict the memory cannot be accessed with a new cue eitherÆ some evidence for suppression FRIENDNEW PHONENUMBEROTHER MEMORY CUESOLD PHONENUMBERInhibitory processes in memory?• Suppression is an example of an inhibitory process• Two paradigms based on idea of inhibition:• Retrieval induced