Accuracy of Eyewitness Testimony

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  • Created by: Moldred
  • Created on: 09-04-16 19:28
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  • Accuracy of Eyewitness Testimony
    • Misleading Information
      • Loftus and Palmer 1974: Leading Questions
        • Experiment 1
          • Results
            • Verbs-Estimated Speed:           smashed-40.8 collided- 39.3 bumped-38.1 hit-34.0          contacted-31.8
          • Procedure
            • sample of 45 students shown series of 7 films of traffic accidents- after each they were given a questionnaire.
            • included one critical question: "about how fast were the cars going when they hit each others?"
            • one group got this question, the other 4 groups were given the verbs smashed, collided bumped or contacted
        • Experiment 2
          • Procedure
            • the sample was divided into 3 groups, they were all shown a film a of car accident and asked to estimate the speed, the verbs were changed within the critical question.
            • a week later they were asked to return, they were asked 10 questions about the video including the critical question "did you see any glass?"
          • Results
            • Smashed: yes-16  no-34 Hit: yes-7 no-43                Collided: yes-6  no-44
        • Loftus and Palmer suggest EWT is largely unreliable, however many psychologists disagree.
          • Yuille and Cutshall found evidence of greater accuracy in real life. Real witnesses of an armed robbery gave accurate reports of the crime 4 months after even though they were originally fed misleading information
      • Conformity Effect
        • Co-witnesses may reach a consensus view on what actually happened.
        • matched pairs p's watched a different video to the other, condition A encouraged the pairs to discuss what happened in the video, 71% of p's mistakenly recalled items they learnt during the discussion
      • Repeat Interviewing
        • every time a witness is interviewed comments from the interviewer may become incorporated with their recollection of the event.
        • an interviewer may ask leading questions and therefore alter the individuals memory of the events. this is especially the case with children .
      • Theres supporting evidence for misleading information. Loftus conducted a study using information about Disneyland. The information mentioned either Bugs Bunny, Ariel or neither.
        • p's in the Ariel or Bugs Bunny conditions were more likely to report that they remember shaking hands with either character. This shows that misleading information can create a inaccurate (false) memory.
      • individual differences may effect EWT.an eyewitness acquires information from the event and misleading information. Elderly people are more likely to forget the source of information even though the event is unaffected.
        • as a result elderly people are more prone to the effects of misleading information
    • Effects of Anxiety
      • Anxiety has a negative effect on accuracy
        • stress has a negative effect on memory as well as performance
        • Johnson and Scott 1976: Weapon Focus
          • the view that a weapon in the criminals hand may distract the witness and therefore reduce accuracy of identification
          • Procedure
            • p's sat in a waiting room where they heard an argument in the adjoining room, a man then ran from the room either carrying a grease covered pen or a blood covered knife. p's were asked to identify the man from some photographs
          • Results
            • mean accuracy of identifying the man with the pen was 49% and 33% for the man with the knife
          • research suggests that reduced accuracy of identification from weapon focus may actually be caused by surprise rather than anxiety.
            • p's watched a man storm into a hair salon with a carrying scissors, a handgun, a wallet or a raw chicken. identification was least accurate in the high surprise conditions rather than high threat.
      • Anxiety has a positive effect on accuracy
        • high arousal/anxiety creates more enduring and accurate memories.
        • Christian and Hubinette found evidence of advanced recall from 58 real witnesses of armed bank robberies in Sweden
        • Procedure
          • interviews were carried out over 4-15 months after each robbery.
        • Results
          • recall was better than 75% accurate, witnesses involved more with the event had the best recall
        • A strength of Christianson and Hubinette study is that it looked at anxiety in the context of real life.it may be the case that lab studies do not create the same level as anxiety as watching a real crime does.
          • Deffenbacher agrees with this but found in a review of 34 lab studies that anxiety results in less accuracy in results and real life events are associated with even less accuracy, this is at odds with Christianson's and Hubinette's results.
      • Deffenbacher suggested the Yerkes-Dodson effect can explain inconsistency in the results of studies into accuracy of EWT
        • The Yerkes-Dodson effect shows that very low and very high arousal both have a negative effect on performance, but moderate levels are beneficial
      • Christianson and Hubinette looked at violent crimes however other research into real life EWT have not included violence.
        • witnesses of violent crimes have better recall then those of less violent crimes. This shows that there is no simple rule to the effects of anxiety on EWT accuracy.

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