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8 Cards in this Set
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Eyewitness testimony |
the evidence provided in court by a person who witnessed a crime, with a view to identifying the perpetrator of the crime.
the accuracy of eyewitness recall may be affected during initial encoding, subsequent storage and eventual retrieval. |
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Loftus and Palmer (1974) experiment 1 |
were interested in whether misleading info distorted the accuracy of an eyewitness's immediate recall.
> 45 students shown 7 films of diff traffic accidents. > after each film ppts were given a questionnaire which asked them to describe the incident then answer specific questions about it. > one critical question - "About how fast were the cars going when they hit each other?" > one group of ppts were given this q. The other 5 groups were given the verbs smashed, collided, bumped or contacted in the place of hit.
> the word smashed estimated a higher speed (about 41 mph) than the other groups. The group given the word contacted estimated the lowest speed (about 30 mph)
Shows that the form of questioning can have an effect on a witness's answer to the question. May cause material to be altered before it is stored. |
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Loftus and Palmer (1974) experiment 2 |
Conducted this second experiment to see if indeed memory could be altered by misleading post-event info.
> new set of ppts divided into three groups and shown a film of a car accident lasting one minute, > group one were given the verb smashed, group two were given hit, and the control group 3 did not have any question about the speed of the vehicles. > ppts asked to return one week later and answer a series of ten questions about the accident, including another critical question: - "Did you see any broken glass?" > there was no broken glass in the film presumably those who thought the car was travelling faster might expect that there would be broken glass.
ppts gave higher speed estimates in the smashed condition as before, and were more likely to think they saw broken glass.
suggests that misleading post-event information does change the way info is stored. |
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Loftus et al (1978) SUPPORTING EVIDENCE |
ppts shown slides of events leading up to a car accident
one group were shown a red Datsun stopping at a junction with a STOP sign. The other group were shown a YIELD sign.
later all ppts were given a set of questions. Half of each group has the question "did another car pass the red Datsun while it was at the YIELD sign?" And the other half had the same question but with "STOP sign".
Finally threy were were shown pairs of slides and had to identify which slides were in the original sequence including one pair showing the red Datsun at either a STOP or YIELD sign.
75% of ppts who had consistent questions picked the correct slide, whereas only 41% who had a misleading question picked the correct slide.
this shows that the misleading question affected their recall, as Loftus and Palmer concluded in their original study. |
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Bekerian and Bowers (1983) acquisition or retrieval? |
replicated the stop sign/yield sign study by Loftus et al (1978).
In in the recognition part of their experiment Loftus had presented the slides in random order. Bekerian and Bowers gave the slides in the original order and found that recall was now the same for the consistent and misleading groups.
Shows that ppts' memories were intact in spite of misleading post-event info.
Therefore misleading questions would appear to affect the retrieval of memories rather than their storage. |
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Yuille and Cutshall (1986) EWT in real life |
Interviewed 13 people who had witnessed an armed robbery in Canada.
The interviews took place more than 4 months after the crime and included 2 misleading questions.
despite these questions the witnesses provided accurate recall that matched their initial detailed reports.
Suggests that post-event info may not affect memory in real-life EWT. |
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Wells and Olsen (2003) |
Mistaken eyewitness identification was the largest single factor contributing to the conviction of innocent people. |
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Validity |
> Lab experiments may not be taken seriously > Participants not emotionally involved > Foster et al. -- better identification with real-life set up. |
