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Eyewitness testimony.docx

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McMaster University
Richard B Day

September 23 , 2013 Psych 3CC3: Forensic Psychology Eyewitness Testimony Eyewitness Testimony - Vision is given higher priority in terms of reliability - Eyewitness testimonies are very persuasive to jurors - Becoming more aware that eyewitness testimony isn’t as reliable Eyewitness Errors - Arthur Lee Whitfield released from prison in 2003. Served 22 years of 63- year rape sentence. Two victims identified Whitfield as the rapist. Freed by DNA evidence. - When DNA was first introduced, the assumption was that it would benefit prosecutors the most; has primarily benefited defence - David Hansen charged with rape, kidnapping in 2005 on identification by victim from 1,500 photos. Cleared by DNA evidence. - The more pictures you show the less likely you are to get a proper identification - Marlon Pendleton 1992 rape conviction based on victim identification overturned in 2006 based on DNA test - James Lee Woodard, convicted in 1980 of murder on the basis of two eyewitnesses. Freed by DNA evidence in 2008 after 27 years in prison for murder - Dr. Daniel Thompson, Australian psychologist and memory expert. Detained by police for rape, matched victim’s description. When crime occurred, was on television program describing how one could improved one’s memory for faces. Woman was watching this program when she was raped. - Not remembering where you obtained the information - Cross-racial identification: witnesses have trouble discriminating members from a different racial groups Memory as an Adaptation 1. We don’t have to remember everything  No memory before ~2 years of age  Brain structures  No information about repeated events  Tend not to store information about things that are reoccurring as they are not novel  Memory is a reconstruction from pieces  Based on fragments of information on which we build complete narratives 2. Memory need not be 100% accurate Memory Processes - Encoding  Taking some event and putting it into a form that the memory system can use  Visual memory: imagery or verbal narratives  Depends on the modality - Storage  Encoded information is stored - Retrieval  Retrieving stored memories  Situations in which retrieval can be difficult due to other factors Encoding Factors 1. Exposure duration:  The longer you are exposed the longer it is to be encoded  In lineup studies, longer is better  If crime happens quickly, probability of encoding the information decreases 2. Arousal level:  Moderate is better than high or low  Works to the advantage of criminals 3. Distraction:  Paying attention to one aspect; other aspects do not get encoded  Inattentional blindness (Simons & Chabris, 1999): when concentrating on one thing, we miss other relevant information  Basketball-gorilla study  We do not pay attention if it is focused on something else  Change blindness (Simons & Levin, 1998)  Focusing on a task leads us to miss changes in the scene  More perpetrators (Clifford & Hollin, 1981)  The more individuals, the less likely you are to be identified  Weapon focus (Lotfus, Loftus & Messo, 1987)  Focus attention exclusively on the weapon and can not identify the culprit 4. Distinctiveness:  The more salient, the more likely it is to be encoded  Flashbulb memories?  Public events that affect hundreds of people and are remembered vividly  1963: assassination of John F. Kennedy  Murder of John Lennon  Shuttle explosion 1986  Death of princess Diana  9/11  Researchers interviewed students after the shuttle explosion of 1986; 2 and a half years later, the students were re- interviewed; researchers found that a high proportion of students gave different reports 2 years later and did not recognize the discrepancy and remembered the memories vividly September 24, 2013 Storage/Retrieval Factors 1. Labeling:  Placing verbal labels or interpretations on what is otherwise a visual memory  Asking to put suspect description into words  Explicit or self-generated labels recall effect  Study: shown drawings with labels, then later asked to draw the images. Depending on the labels, the drawings were different  When police ask for descriptions they use many verbal labels 2. Prejudices and biases:  Things we want to see shape what we actually do see  Prejudice bias research: proportion of people who remembered the black man as the shorter painter with a weapon was very high, although it was really the white man who was the aggressive argumentative individual  Recalling their course grades in high school:  Recall a fraction of Ds (305)  50% of C grades were recalled  60% of B grades  90% of A grades  People tend to recall the best things about their experience  Buckhout, 1974  Boon & Davies, 1996  Bahrick et al, 1996 3. Inferences:  Recall things that we never saw at all  Based on our assumptions of what must have been true  Participants told to wait in an office while the experiment was being set up  Participant asked what they recalled in the office  No books were in the office, yet most participants reported books  Drew inference from their expectations since if was a professors office there must have been books  Bower & Treyens, 1981 4. Interpolated retelling/testing:  We are rehearsing the aspects in reports which strengthens the memory of these events  Details that were not asked about after the event tend to become less easy to recall and these details may no longer be elicited  Police officers have a bias about things they want to know: ask certain questions repeatedly and others not at all making eye witness testimony less accurate 5. Leading questions  Leading questions bias our recall of what have gone on  Once the question has been asked you have already produced a bias even if the question has not been answered  Loftus & Palmer, 1974  Loftus & Zanni, 1975  Loftus et al, 1978  Harris (1973):  How tall was basketball player? 79in  How short was basketball player? 69in  How long was the movie? 130mins  How short was the movie 100mins  Loftus (1975):  How many products tried. 1,2,3? 3.3  How many products tried. 1,5, 10? 5.2  Headaches frequently? How often? 2.2/week  Headaches occasionally? How often .7/week  Speed estimates – Loftus and Palmer:  Individuals shown short film of two cars colliding with each other and having an accident  Asked to estimate what was the speed of the two cars when they _______ into each other  Smashed and collided gave a much higher estimate  Hit was moderate  Contacted and bumped had lower speed estimates  After a week, the same participants are brought back and are asked whether or not there was broken glass  Control group: 45% said there was no glass; 5% said yes  Hit group: roughly the same proportion as control  Smashed: 15% said yes  As the vigour of the collision increases given the wording, the proportion of participants who say they saw the glass increases dramatically  Bias is reduced according to their original estimate of speed – increases more dramatically for the smashed group  Effect of estimated speed that makes the greatest mistake  Individuals memory after a week has been altered due to the leading question asked after the test  Individuals shown a still image of a room  Asked whether or not there was a lamp on the table or was there a lamp on a table  A week later when asked if there was a table there was a higher proportion of ‘yes’ in the group asked “the” than the “a” group 6. Post-event information (PEI):  Related to leading questions  Things that you are told about the event that you have experienced that are inaccurate  Individuals shown a film  One group is given two questions: one which is a leading questions  A few days later asked a related question  Those who were in the inaccurate information group will choose the inaccurate information over the accurate information  Loftus, 1975  McCloskey & Zaragosa, 1985  Loftus, Donders, Hoffman & Schooler, 1989  Loftus, 1991  What happens to the accurate information? Does it still exist or is it lost?  It may be possible to recover the real initial memory  Creating false memories about the event False Memories - Loftus & Pickrell, 1995: being lost in a mall  Asked parents things that had happened in childhood  Children asked to describe each of the memories  Asked to recollect being lost in a mall  30% of participants recalled after having thought about it for a while, highly detailed stories - Hyman, Husband & Billings, 1995: causing trouble at a wedding - Porter, Yuille & Lehnam, 1999: attacked by a viscious animal - Heaps & Nash, 2001: saved from drowning by a lifeguard - Mazzoni & Mmon,2003: having a skin sample taken as a child - Can we get kids to create false memories?  Asked children for 6-8 in a row a question: do you remember a particular event  First couple of weeks children had no recollection  By 6-8 weeks, had a full description about the event  After the study the children were debriefed, yet still believed in the event and are confident that they are true  Isn’t the event itself, but the interpretation that you place on it that makes you an abused child September 26 , 2013 Wise et al (2009); Attorneys and Eyewitness Testimony - 75 prosecutors, ~1200 defense attorneys completed 13-question survey - Witness’s ability to recall minor crime details is good indicator of accuracy of perpetrator ID – unrelated to the accuracy of identification - Lineup should not be conducted by officer who knows which individual is the suspect – true - Eyewitness testimony based partly on information obtained later from police, media, other witnesses – true - Presence of weapon can affect ability to accurately identify perpetrator’s face – true - High levels of stress can impair accuracy of eyewitness testimony – true - Juror can distinguish between accurate and inaccurate eyewitnesses - false - Prosecuting attorneys have a higher and inaccurate estimate of how well eyewitnesses do - Defense attorneys are well versed on eyewitness testimonies Offender Descriptions - Verbal and pictorial descriptions of perpetrators - Verbal descriptions - Research looks at how well and how fully victims describe perpetrators - Studies looking at real cases of perpetrator descriptions or mock crime studies - Descriptions are very varied in the mock crimes - The sex of the offender is never missed - We know from anecdotal demonstrations, that the ability to remember a culprit is impaired - Kuhn et al (1974): cases involving robbery. Rape, or assault  Gender  Age  Height  Build  Race  Weight  Face (hair colour, complexion)  Mean = 7.2 descriptions  Fairly obvious characteristics  The best descriptors are the ones that will be less likely described, i.e., facial features  Rarely given descriptors about facial features  Descriptors that tend to be provided are not very helpful - Sporer (1992):  Gender  Age  Height  Build  Race  Weight  Clothing (31%)  Face (30%)  Provide information about the upper face  Hair colour and style  Things that are very easily changed  Do not talk about shape of nose, shape of chin, eye colour, or facial hair  Mean = 9.7 descriptors Lindsay et al (1994) - Compared descriptions of witnesses to real crimes and witnesses to mock crimes - Real Crime:  Gender (96%)  Clothing (60%)  Hair colour (38%)  Race (25%)  Face (<10%)  Mean = 3.94 - Mock crime:  Clothing (99%)  Hair colour (90%)  Height (86%)  Eyes (43%)  Race, age, sex (<50%)  Other face (<25%)  Mean = 7.35 descriptors  Provided significantly more descriptors but not useful information Van Koppen & Lochun (1997) - Made lists of information you can provide from an offender and divided the list into permanent features (remain unchanged) and temporary features (things about an individual which can be changed) - Real crimes - 24 permanent features (gender, age, skin colour)  Provided more permanent features than temporary features  Median = 5  Inner face = <5%  Eye colour = 36%  Nose = 35%  Mouth = 40%
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