Credibility in the courtroom: how likeable should an expert witness be?

This study was conducted to investigate the relationship between expert witness likeability and jurors' judgments of credibility and tendencies in sentencing. Two actors playing expert witnesses were trained to present themselves as high and low in likeability in a standard testimony scenario in the sentencing phase of a capital murder trial. The effects of extraversion and gender of the 210 psychology undergraduates serving as mock jurors attending to expert testimony were also examined. The dependent variables were the jurors' perceptions of the witnesses' credibility and their agreement with the testimony. The likeability of the expert witnesses was found to be significantly related to the jurors' perception of their trustworthiness, but not to their displays of confidence or knowledge or to the mock jurors' sentencing decisions. The women rated highly likeable experts as more credible than the less likeable ones, but the men did not differentiate between the two types. As extraversion increased, the male jurors' agreement with testimony increased, but the female jurors' agreement decreased. The results suggest that likeability can be an important element in the credibility of the source and that attorneys and trial consultants now have an empirical foundation for addressing likeability as part of witness preparation.