Search

This survey of 206 forensic psychologists tested the "filtering" effects of preexisting expert attitudes in adversarial proceedings. Results confirmed the hypothesis that evaluator attitudes toward capital punishment influence willingness to accept capital case referrals from particular adversarial parties. Stronger death penalty opposition was associated with higher willingness to conduct evaluations for the defense and higher likelihood of rejecting referrals from all sources. Conversely, stronger support was associated with higher willingness to be involved in capital cases generally, regardless of referral source. The findings raise the specter of skewed evaluator involvement in capital evaluations, where evaluators willing to do capital casework may have stronger capital punishment support than evaluators who opt out, and evaluators with strong opposition may work selectively for the defense. The results may provide a partial explanation for the "allegiance effect" in adversarial legal settings such that preexisting attitudes may contribute to partisan participation through a self-selection process.

The knowledge of experts presumably affects their credibility and the degree to which the trier of fact agrees with them. However, specific effects of demonstrated knowledge are largely unknown. In this experiment, we manipulated a forensic expert's level of knowledge in a mock-trial paradigm. We tested the influence of low versus high expert knowledge on mock juror perceptions of expert credibility, on agreement with the expert, and on sentencing. We also tested expert gender as a potential moderator. Knowledge effects were statistically significant; however, these differences carried little practical utility in predicting mock jurors' ultimate decisions. Contrary to the hypotheses that high knowledge would yield increased credibility and agreement, knowledge manipulations influenced only perceived expert likeability. The low-knowledge expert was perceived as more likeable than the high-knowledge counterpart, a paradoxical finding. No significant differences across expert gender were found. Implications for conceptualizing expert witness knowledge and credibility and their potential effects on juror decision-making are discussed., (© 2015 American Academy of Psychiatry and the Law.)