Applied Cognitive Psychology

This study assesses whether mock jurors’ perceptions of eyewitness expert testimony vary based on the level of ecological validity—video or transcript trial presentation medium. In Experiment 1, 496 jury-eligible mock jurors were presented a simulated trial. Each served in one condition in a 3 (no expert or eyewitness expert either with or without prosecution rebuttal witness) 2 (trial presentation medium: Video or transcript) design. Participants were generally less certain of the defendant’s guilt after the eyewitness expert testimony, and affective and cognitive ratings of the expert testimony were higher in the transcript than video condition. However, there were no significant interactions of modality with expert conditions, thus reducing concerns that jury simulation research must be conducted with live or video trials to be externally valid. Findings were replicated in Experiment 2 using the testimony of a different eyewitness expert rated to have a more dynamic communication style. Copyright # 2009 John Wiley & Sons, Ltd.