Eyewitness Testimony

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Inaccurate and distorted

Eyewitness testimony (EWT) is the evidence provided by people who witnessed a particular event or crime. It relies on memory recall.

EWT includes, for example, desriptions of criminals and crime scenes.

Witnessesare often innacurate in their recollection of events and the people involved. 

Many cognitive psychologists focus on working out what factors affect the accuracy of EWT, and how accuracy can be improved in interviews.

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EWT affected by misleading information

Loftus and Palmer (1974) investigated how misleading info can be distorted. They used leading questions, where a certain answer is implied in the question. 

EXPERIMENT 1

Method:

  • Participants shown a film of a car crash.
  • They were then asked a series of questios including 'How fast do you think the cars were going when they hit?'. 
  • In different conditions, the word 'hit' was replaced with 'smashed', 'collided', 'bumped' or contacted.

Results:

  •  Participants give the word 'smashed' estimated the highest speed; those given the word 'contacted' gave the lowest estimate.
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EWT affected by misleading information

EXPERIMENT 2

Method:

  • The participants were split into three groups.
  • One group given the verb 'smashed', another 'hit', and the third,  control group wasn't given any indication of the vehicles' speed. 
  • A week later, the participants were asked 'Did you see any broken glass?'

Results:

  • Although there was no broken glass in the film, participants were more likely to say that they'd seen broken glass in the 'smashed' condition than any other.

Conclusion:

  • Leading questions can affect the accuracy of people's memories of an event.
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EW

Evaluation:

  • This has implications for questions in police interviews.
  • Artificial experiment.
  • Later study found that participants who thought they'd witnessed a real robbery could give an accurate description of the robber. 
  • Experimental design might lead to demand characteristics - results skewed.
  • The leading questions could have given the participants clues about the nature of the experiment - participants could have acted accordingly - reducing the validity and reliability of the experiment.
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Loftus and Zanni (1975)

Als looked at leading questions.

Method: 

  • Participants shown a film of a car crash. They were then asked either 'Did you see the broken glass?' or "Did you see a broken headlight?'. 
  • There was no broken headlight shown in the flim.

Results:

  • 17% of those asked about the 'broken headlight' claimed they saw one, sompared to the 7% in the group asked abut 'a' broken headlight.

Conclustion:

  • The simple use of the word 'the' is enough to affect the accuracy of people's memories of an event.
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Loftus and Zanni (1975)

Evaluation:

  • Lab study - highly controlled.
  • Can establish cause and effect.
  • Artificial - lacks ecological validity.
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Post-event discussion

Studies where a confederate has been used to feed other participants with misleading post-event information have shown that this can affect recall. For example:

Shaw et al (1997) paired participants with a confederate. The pairs were shown videos of a staged robbery and were interviewed together afterwards. The participant and the confederate alternated who answered the wuestions first. When the participant responded first, recall was accurate 58% of the time. When the confederate answered first and gave accurate answers, the recall of te participants was 67%. If the confederate gave inaccurate answers, correct recall for the participants fell to 42%.

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Post-event discussion

If the misleading information is recieved through a conversation, the effects can be just as big, if not bigger. For example:

Gabbert et al's (2004) study involved two groups of participants - young adults and older adults. Both groups watched a staged crime and were then exposed to misleading infomration in one of two days - through conversation with a confederate who was pretending to be another participant, or reading a witten report of the crime, supposedly written by another participant. The participants were then given a recall test about the event they'd witnessed. It was found that both groups of adults were more likely to report inaccurate information after a conversation with a confederate than after reading the report. 

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EWT affected by age

Studies have shown that the age of the witness is a factor in whether they're affected by leading questions.

Valentine and Coxon (1997)

Method:

  • Three groups of participants (children, young adults and elderly people) watched a video of a kidnapping. 
  • They were the asked a series of leading and non-leading questions about what they had seen.

Results:

  • Both thre elderly people and the children gave more incorrect answers to non-leading questions.
  • Children were misled more by leading questions than adults or the elderly.

Conclusion:

  • Age has an effect on the accurcy of EWT.
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EWT affected by age

Evaluation:

  • This has implications in law when children or elderly people are questioned.
  • Experiment was artificial - lacks ecological validity.
  • Results may only show how well people remember things from TV, rather than showing the accuracy of memories of real-life situations. 
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Anxiety

Psychlogists tend to believe that small increases in anxiety and arousal may increase the accuracy of memory, but high levels have a negative effect on accuracy.

In violent crimes the witness may focus on central details and neglect other peripheral details.

Loftus (1979) - Weapon focus in EWT

Method: 

  • Independent groups design.
  • Participants heard a discussion in a nearby room. In one condition, a man came out of the room with a pen and grease on his hands. In the oter condition, the man came out of the room with a knife covered in blood. Participants were asked to identify the man from 50 photos.

Results:

  • Participants in condition 1 were 49% accurate.
  • 33% of the participants in condition 2 were accurate.
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Anxiety

Conculsion:

  • When anxious and aroused, witnesses focus on a weapon at the expense of other details. 

Evaluation:

  • High ecological validity, as participants wern't aware of the study.
  • Ethical condiserations, participant's could have been scared of the man with the knife.
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Misleading questions and anxiety

Msleading questions and anxiety don't always affect EWT.

A field study for Yuille and Cutshall (1986) showed that witnesses of a real inclident had remarkably accurate memories of the event.

A thief was shot and killed by police and witnesses were interviewed. Thirteen of them were invited to be re-interviewed five months later. Recall was found to be highly accurate, even after this time period.

The researchers had interviewed two misleading questions in the study but these were found to have no effect on the subjects' answers. 

This study had hih ecological validity - based on a real event. However, the witnesses who experienced the highest levels of stress were also closest to the event - it's difficult to determine whether proximity or stress contributed to the accuracy of their recall.

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The cognitive interview

Cognitive psychologists have played a big part in helping to increase the accuracy of EWT.

The cognitive interview technique (CIT) was developed by Geiselman et al (1984) to try and increase the accuract of witnesses' recall of events during police questioning.

  • The interviewer tries to make the witness relaxed and tailors their language to suit the witness.
  • The witness mentally recreates the environmental context and internal context of the ctime scene. 
  • The witness reports everything that they can remember about the crime, even if it feels irrelevant.
  • The witness is asked to recall the details of the crime in different orders.
  • The witness is asked to recall the event from various perspectives.
  • The interviewer avoids any judgemental and personal comments.
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Support for the cognitive interview

Geiselman et al (1986) - The effect of the cognitive interview.

Method:

  • In a staged situation, an intruder with a blue rucksack entered a classroom and stole a slide projector.
  • Two days later, participants were questioned about the event.
  • Independent groups design - participants were either questioned using a standard interview procedure or the cognitive interview procedure.
  • Early in the questioning, participants were asked 'Was the guy with the green backpack nervous?'.
  • Later in the interview, participants were asked about the colour of the man's racksack.

Results:

  • Participants in the CIT condition were less likely to recall the rucksack as being green than those in the standard interview condition.
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Support for the cognitive interview

Conclusion:

  • The CIT reduces the effect of leading questions.

Evaluation:

  • High ecological validity
  • Independent groups design - participants could have naturally been less susceptible to leading questions than the other group (due to individual differences).
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