Faculty and Staff

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.

Prosecutors are handling increasing numbers of criminal cases concerning veterans from the wars in Iraq and Afghanistan who suffer from posttraumatic stress disorder (PTSD). How these prosecutors handle such cases may reflect their attitudes toward veterans or offenders with PTSD. In turn, their attitudes may affect perceptions of blameworthiness, as well as negotiations about sentencing during the pre-trial stage. The present study investigated the effect of a defendant’s military experience and mental health status (i.e., PTSD) on prosecutors’ offers at the pre-trial stage and their ratings of the defendant’s blameworthiness. Prosecutors’ offers were more lenient to stress-disordered veterans; specifically, they were offered more diversion programs compared to veterans without PTSD and to other offenders with PTSD. Prosecutors also perceived veterans and those with PTSD as less criminally culpable; they also empathized and identified more with veterans and those with PTSD than non-veterans and offenders without PTSD.