Faculty and Staff

Despite advances in the scientific methodology of witness testimony research, no sound measure currently exists to evaluate perceptions of testimony skills. Drawing on self-efficacy and witness preparation research, the present study describes development of the Observed Witness Efficacy Scale (OWES). Factor analyses of a mock jury sample yielded a two-factor structure (Poise and Communication Style) consistent with previous research on witness self-ratings of testimony delivery skills. OWES subscales showed differential patterns of association with witness credibility, witness believability, agreement with the witness, and verdict decision. Juror gender moderated the impact of Communication Style, but not Poise, on belief of and agreement with the witness. Results are discussed with attention to application of the OWES to witness research and preparation training.

The knowledge of experts presumably affects their credibility and the degree to which the trier of fact will agree with them. However, specific effects of demonstrated knowledge are largely unknown. This experiment manipulated a forensic expert’s level of knowledge in a mock trial paradigm. We tested the relation between 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 hypotheses that high knowledge would yield increased credibility and agreement, knowledge manipulations only influenced perceived expert likeability. The low knowledge expert was perceived as more likeable than his or her high knowledge counterpart, a paradoxical finding. No significant differences across expert gender were found. Implications for conceptualizing expert witness knowledge, credibility, and their potential effects on juror decision-making are discussed.