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9 Cards in this Set
- Front
- Back
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Aim |
To investigate whether the presence of an expert witness would affect the juror's decision making ability.
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Method |
Laboratory experiment using a videotaped mock trial of a robbery |
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Participants |
538 undergraduates |
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Procedure |
- Participants were divided into two groups and shown video tape and after they individually completed a questionnaire, containing the dependent measures (verdict, memory test and rating scale of how confident they were with their verdict) |
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4 IV's |
1. Witness Identifying condition - good (no disguise, gun, 2 day delay in identification) and poor (disguised, handgun, 14 day delay( 2. Witness confidence - Witness said they were either 80% or 100% sure their identification was correct 3. Form of testimony - Expert witness either gave a descriptive testimony or relied on figures 4. Expert opinion - Expert expressed an opinion on a scale of 0-25 on the accuracy of the testimony. |
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Results |
- Jurors gave more guilty verdicts when WIC were good this increased if the psychologist used simple descriptive language - More juror confidence in the good WIC condition - jurors also expressed more confidence when eyewitness claimed to be 100% sure of their identification - 85% of jurors remembered the trial accurately |
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Conclusion |
The expert testimony improved the jurors knowledge of factors that might affect the accuracy of eyewitness testimony and make them pay more attention to the Witness Identification Condition |
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Evaluation - Strengths |
- Construct validity - results show support for Yale Model of Persuasion - Reliability - both the large sample and the methodology male this experiment highly reliably - Quantitative data - easy to compare and analyse and can establish cause and effect |
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Evaluation - Weaknesses |
- Ecological Validity - psychology students whoa re not representative, in groups of 2 - 8 when real jury is 12. Jury saw crimes on video however jury did deliberate in groups. - Qualitative data - lack of in this study does not provide us with any detail - Demand characteristics - Participants were given credit of taking part, so may act in a desirable way - Ethnocentrism - Only American psychology students which is not representative and therefore cannot generalise to other countries or legal systems |
