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The effect of the expert witness on jury perception of EWT

The effect of the expert witness on jury perception of EWT. By Cutler et al. Todays session . All students to complete the section “persuading a jury” by ensuring all elements to the areas are understood All students to complete tasks either in booklet or set in class

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The effect of the expert witness on jury perception of EWT

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  1. The effect of the expert witness on jury perception of EWT By Cutler et al

  2. Todays session • All students to complete the section “persuading a jury” by ensuring all elements to the areas are understood • All students to complete tasks either in booklet or set in class • All students to consider how these could be applied to an exam question • Some students to start to develop a 10 and 15 mark answer

  3. Aim • Does hearing about psychological research from an expert witness affect Juror-decision-making by making them more sceptical about EWT?

  4. Participants • 538 undergraduate students who gained credits for taking part • What is problematic about using only a student population? • Is this sample generalisable?

  5. Method • Laboratory experiment (videotaped mock trial of a robbery) • What is the problem with setting up mock juries to understand real jury behaviour? • What is positive about having a mock jury set up by a researcher?

  6. Procedure • All P’s viewed a video-taped mock trial of a robbery & then each P completed a questionnaire (measuring DV’s) • IV 1. Witness identifying conditions (WIC)- either GOOD (no disguise, a hidden gun, a 2-day delay in ID & no suggestive instruction during line-up) or BAD (disguise, a handgun, 14-day delay in ID and suggestive instructions during line-up)

  7. IV 2. Witness confidence-she was either 100% or 80% confident that their ID was correct • IV 3. Form of testimony-either expert witness gave a descriptive testimony about EWT or relied on % & figures. • IV 4. Expert opinion-expressed opinion on accuracy of EWT on scale of 0 (least likely to be correct)-25 (most likely to be correct) (this coincided with good or bad WIC)

  8. DV’s • The Verdict- guilty/not guilty • A memory test- Expert testimony recalled • 3. Confidence of P’s in their verdict • Why were there three DV’s?

  9. Results • Juror verdicts: Good WIC lead to more guilty verdicts (increased with expert witness who gave descriptive testimony) • Juror memory: 85% p’s correctly recalled testimony (so poor memory can not be blamed for lack of effect on juror’s judgement) • Juror confidence: High in good WIC , stronger if witness confidence was 100% & increased if expert witness also expressed confidence.

  10. Conclusion • Expert testimony improved juror knowledge & made them pay more attention to WIC. • Expert testimony decreased the reliance on witness confidence alone. • No evidence that expert testimony made the jurors sceptical about the witness’ credibility. • With expert testimony, juror sensitivity to problems with evidence is improved & may help prevent miscarriages of justice.

  11. Phil Spector…. • Read the hand out and in small groups decide whether the expert witness helped persuade the jury • http://www.theguardian.com/world/2009/apr/14/phil-spector-lana-clarkson-murder

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