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