Eye Witness Testimony

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  • Created by: Sess
  • Created on: 12-12-14 10:23
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  • Eye Witness Testimony
    • 1) Event Factors:
      • A) Stress
        • Loftus & Burns (1982)
        • 1) Ppts were shown 2 versions of a crime, one was a violent series of slides, the other was non-violent.
        • 2) Ppts who saw the violent version could remember significantly less details of the crime.
      • B) Content
        • Loftus et al (1987)
        • 1) Showed uni students a series of slides, one with a weapon and one without
        • 2) When asked to identify suspect from slides, the group that saw the weapon were less accurate in identifying them.
    • 2) Witness Factors:
      • A) Expectations
        • Allport & Postman (1947)
        • 1) A picture was shown to ppts, depicting a Caucasian man beginning a conflict with an African-American.
        • 2) When asked to recall a few weeks later, ppts states that the other man started it.
        • 3) This links to Bartlett, ppts expectations distorted the story.
      • B) Confidence
        • 1) Witnesses are asked their story so many times, they get more confident.
        • 2) This influences the jury into thinking they know what they are talking about.
    • 3) Identification Techniques
      • A) Identification Parades
        • Valentine et al (2003)
        • 1) They looked at 640 identification parades, 60% were unsuccessful
        • 2) 20% picked the wrong person, 40% just didn't identify
        • 3) Valentine concluded that this may be due to a variety of factors such as facial hair, view point etc.
      • B) CCTV Issues
        • Bruce et al (1998)
        • 1) They conducted a series of studies into various aspects that affect identification from CCTV footage.
        • 2) One study involved asking ppts to match a computer generated face to another lit from various lightening angles.
        • 3) They found that the ppts could match the faces better if the lighting and viewpoints were the same.
      • Identification parades can be improved by:
        • Using a sequential line up so pressure to pick is reduced
        • Not showing the witness any pictures of the suspect beforehand
        • Balancing out parades in terms of physical characteristics
    • 4) Post Event Interference:
      • A) Substituting Information
        • Loftus (1975)
        • 1) Showed ppts slides of a car accident. One group saw a stop sign, the other a yield sign
        • 2) The 2 groups were split further and half of each group was asked about a stop sign, and the other half about a yield sign
        • 3) 75% of the groups that saw and were asked about the same sign agreed they saw the sign
        • 4) 59% of the groups that saw one sign and were asked about another, agreed they saw the sign they were asked about.
      • B) Adding Information
        • Loftus (1974)
        • 1) Ppts were shown a film of a crash.
        • 2) Group A were asked did you see A headlight, group B were asked did you see THE headlight.
        • 3) Group B gave more positive results, even tho there was no headlight.
      • C) Distorting Information
        • Loftus & Palmer (1974)
        • 1) Ppts were again shown slides of a car crash.
        • 2) Ppts were then split into groups and asked variations of the following question: 'how fast were the cars going when they hit each other?'
        • 3) The verb 'hit' was changed to collided or smashed etc.
        • 4) The ppts that heard 'smashed' estimated the cars to be going at faster speeds than those that heard 'hit'.
    • The Devlin report (1973) revealed that out of 2000 line-ups, 45% resulted in a perportrator being picked out
    • Of that 45%, 82% resulted in a conviction
      • Of 2000 cases, 350 had only EWT as  evidence and 74% resulted in conviction
    • This means that EWT is of high importance. But is it accurate?

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