Persuading a Jury - Expert Witness, Cutler

  • Created by: sali97
  • Created on: 24-05-16 10:56
To investigate whether the presence of an expert witness would affect the juror's decision making ability.
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Lab experiment using a videotaped mock trial.
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538 American psychology students who were given extra credits.
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Participants were shown a videotape of a robbery in groups. Afterwards, they independently completed a questionnaire,which included their verdict, a memory test and rating how confident they were in their verdict. There were four IVs
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1, Witness Identification Condition: good or bad. 2, Witness confidence: 100% or 80%. 3, Expert Opinion Expressed: 0-25 point scale. 4, Form of Expert Testimony: descriptive or statistics
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Jurors gave more guilty verdicts when WIC's were good which increased if the psychologist used ordinary language. 85% jurors remembered what the expert psychologist said. Jurors also expressed more confidence when the witness was 100% sure.
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Expert testimony improved juror’s knowledge of factors that affect the accuracy of EWT and made them pay more attention to WIC. With expert testimony, sensitivity to problems with evidence is improved and may help prevent miscarriages of justice.
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Jurors tend to think that witnesses are accurate and trustworthy. However, they lack knowledge of factors that might affect witnesses’ memory of the events, such as: weapon focus effect, leading Qs and delay of testimony.
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Background #2
This may have serious consequences for the accused, so sometimes, the defence calls in expert psychologists to explain to the jury why the witness testimony may not be accurate or reliable.
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Ads of Expert Witness
This adds scientific credence to the evidence and helps clarify complex issues to the jury so they can be more confident about making a verdict based on the evidence provided.
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Loftus's study
aimed to assess the influence an expert witness can have on juror’s acceptance of eye witness evidence.
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Loftus's study - procedure
Half cases- statement from expert who provided evidence about the unreliability of the EWT (weapon focus effect and witness drinking). other half - No vidence about the problems associated with reliance on EWT evidence.
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Loftus's study - Results and Conclusion
Results showed that those who received the expert testimony spent longer discussing the eye witness evidence and were less likely to find the defendant guilty. Therefore, expert witness influences juror’s decision.
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Lab experiment using a videotaped mock trial.

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