Thesis

Predictive value of pretrial attitudes and the influence of eyewitness credibility on juror decision making

The present study examined the effect of eyewitness credibility level on verdict outcome, juror verdict confidence, prosecution and defense case strength ratings, and perceived credibility ratings for the eyewitness, police officer, and alibi witness. It was predicted that those who read testimony from a highly credible eyewitness would favor the prosecution’s case more than those who read testimony from a less credible eyewitness. Pretrial juror conviction biases were predicted to moderate the effect of eyewitness credibility; those with higher levels of conviction bias would be less affected by the low eyewitness credibility manipulation. The participants (N = 99) were randomly assigned to either the low or high eyewitness credibility condition after completing the Pretrial Juror Attitudes Questionnaire (PJAQ). After reading a brief trial transcript describing an armed robbery and first-degree murder case, the participants were asked to render a verdict, rate their confidence in their decision, rate the attorneys’ case strengths, and evaluate the witnesses. None of the hypotheses were supported by the data analysis. However, the eyewitness credibility manipulation produced significant group differences on verdict confidence and perceived eyewitness credibility. The PJAQ subscales predicted the case strength of the prosecution and the witnesses’ credibility ratings, although the direction of these relationships varied. The unexpected findings of the present study reflect the need for more refined legal research on the factors that influence juror decision making.

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