Expert witness confidence and juror personality: their impact on credibility and persuasion in the courtroom.

The present study was conducted to investigate the relationship between both expert witness confidence and juror personality with expert witness credibility, as well as expert witness credibility with juror sentencing outcome. Participants were presented with one of three randomly assigned filmed scenarios depicting various levels of manipulated witness confidence. They then completed a sentencing outcome item, the Witness Credibility Scale, and the Goldberg Five-Factor Markers. Expert witness confidence had a significant main effect on ratings of credibility, with moderate levels of manipulated confidence yielding the highest credibility. Juror extroversion was positively related to perceptions of expert witness credibility. Finally, juror ratings of expert witness credibility, as well as two subcomponents, predicted juror sentencing outcome.