Prof. Greg Francis 8/14/12 PSY 200: Intro. to Cognitive Psychology 1 Purdue University Constructive memory PSY 200 Greg Francis Lecture 20 How good is eye-witness testimony? Purdue University Memory test  Last lecture you watched me for 50 minutes  What was I wearing? Purdue University Discrimination  The task is difficult because you have to do several things  Recall information that might be related to the task from memory  Determine if the memory is actually for the correct event  Determine if the memory is actually for the correct moment in time  Gauge your confidence in the memory’s validity  All of this suggests that performance on a memory task involves discriminating information  To address the discrimination problem, people engage in a constructive process to report memories Purdue University No forgetting?  Brain surgeon (Penfield, 1959)  Epilepsy patients  stimulate brain regions before operating  want to know what is being removed  Conscious patients report vivid memories  unable to recall normally » "she saw herself as she had been while giving birth to her baby."  stimulation of temporal lobes  In the image, numbers indicate places where stimulation evoked different reported experiences Purdue University No forgetting?  Suggests that memories are stored but normally unreachable (context things again)  Basis for ideas of memory repression (and a few self-help books)  The results are usually misunderstood  Actually only occurred for 5% of patients Purdue University Penfield (1959)  Even worse…  the memories are nearly impossible to verify  the few attempts find that the “memories” are not true » people describe places they have never visited, impossible events, fantasy,…  The patients have epilepsy » Stimulation may have triggered something like an epileptic seizure (which can have hallucinations)  It is more likely that stimulation “feels like” a memory, even though it is not  your awareness of “remembrance” is a product of your brain  it can be stimulated, even without a real memory  What do we mean by a valid memory?Prof. Greg Francis 8/14/12 PSY 200: Intro. to Cognitive Psychology 2 Purdue University Flashbulb memories  Highly emotional events tend to produce strong memories  e.g.  JFK assassination  Challenger explosion  Oklahoma City bombing  Earthquakes  September 11, 2001  ... Purdue University Flashbulb memories  People vividly recall details surrounding event  where they were when they heard  what people said  clothing worn  time of day,..  People are confident about their reports  however... Purdue University Flashbulb memories  Talarico & Rubin (2003)  On September 12, 2001  Asked volunteers to answer questions about their memory of  The WTC attack  An ordinary event (volunteer’s choice)  Three groups for follow up  7 days later  42 days later  224 days later  Recalling of details was the same for WTC attack and ordinary event Purdue University Flashbulb memories  The memories of the WTC attack were more vivid  Subjects believed those memories were more likely to be reliable  Ordinary memories  Faded in vividness  Belief decreased over time Purdue University Flashbulb memories  Subjects confidence in their memory can be misleading  retelling of the story (“I remember vividly when Kennedy was shot. I was…”) probably reinforced the story  Maybe not the true memory  Flashbulb memories are a real phenomenon about the experience of memory,  but probably not “super-memory” Purdue University Memory misattribution  Donald Thomson was accused of rape and picked out of a lineup by the victim (Schacter, 1996)  He was on live TV at the time of the rape  Ironically, he was discussing memory of faces for eyewitness testimony  The victim  had the TV on at the time of rape  misattributed the face on TV for the face of her attacker  very accurate report of the crime, otherwiseProf. Greg Francis 8/14/12 PSY 200: Intro. to Cognitive Psychology 3 Purdue University Eyewitness testimony  I will show you a series of slides and then ask you some questions Purdue University PSY 332: Cognition 14 Dr. Kim Vu Purdue University Purdue University PSY 332: Cognition 16 Dr. Kim Vu Purdue University Purdue University PSY 332: Cognition 18 Dr. Kim VuProf. Greg Francis 8/14/12 PSY 200: Intro. to Cognitive Psychology 4 Purdue University Purdue University PSY 332: Cognition 20 Dr. Kim Vu Purdue University PSY 332: Cognition 21 Dr. Kim Vu Purdue University Questions  Did the bus, which came by, come from the left or the right?  Did another car pass the Red Datsun while it was at the intersection with the stop sign?  Did you see a bicycle?  Did you see the taxi cab?  Did you see if the policeman wrote anything down? Purdue University Purdue UniversityProf. Greg Francis 8/14/12 PSY 200: Intro. to Cognitive Psychology 5 Purdue University Purdue University Purdue University Purdue University Eyewitness testimony  Later, show slides and ask subjects if they were part of the original set  real slide contains YIELD sign  fake slide contains STOP sign Purdue University Eyewitness testimony  “Misinformation effect”  Compare accuracy according to pre-test questions  Subjects without a misleading question--90% accurate  Subjects with a misleading question -- 20% accurate  In a follow-up, the experimenters asked those with misleading questions if they thought they were misled » 90% say no  Paying money for correctness also had no effect Purdue University Eyewitness testimony  Loftus, Miller & Burns (1978)  The misinformation effect gets stronger with a week delay before the memory test 01020304050607080Consistent None MisleadingPercentage correctDelayedImmediateTypes of questions"Prof. Greg Francis 8/14/12 PSY 200: Intro. to Cognitive Psychology 6 Purdue University Memory implants  Loftus has a procedure that “implants” a memory of being lost in a mall  Basically just have subject read a