Credibility in the Courtroom: How Likeable Should an Expert Witness Be? Stanley L. Brodsky, PhD, Tess M. S. Neal, MA, Robert J. Cramer, MA, and Mitchell H. Ziemke, MA 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. J Am Acad Psychiatry Law 37:525–32, 2009 A growing body of literature on expert testimony 1,2 has described the need for study of the behavioral components associated with effective testimony. The purpose of the present study was to investigate one component, expert witness likeability, utilizing a the- oretically derived framework for credibility. We be- gin by reviewing source credibility and the literature about perceiver variables related to source likeability. Source Credibility The topic of source credibility has been substan- tially discussed in the psychological literature. Mc- Croskey and Young 3,4 established much of the con- ceptual and empirical groundwork on the subject. In their 1981 discussion of the state of source credi- bility theory and research, 4 they identified eight factor analysis-supported components of credibility: sociability as reflected in ratings of pleasantness, friendliness and warmth; extroversion as reflected in ratings of talkativeness, boldness and aggression; calmness as reflected in ratings of poise, relaxation, and calm; competence as reflected in ratings of ex- pertise and intelligence; character as reflected in rat- ings of honesty and trustworthiness; and additional ratings of size (large-small), time (early-late), and weight (skinny-fat). The authors point out that size, time, and weight are part of general ways in which individuals perceive other people. They concluded that these eight components could be collapsed into two overarching domains of credibility: competence and character. These domains are similar to the more recent conceptions of knowledge and trustworthi- ness reported by Brodsky 1 in the context of expert witness credibility. Griffin and colleagues 5 have identified four em- pirically supported domains of courtroom credibil- ity: trustworthiness, knowledge, confidence, and likeability. The components of credibility in the courtroom may be more specific than the compo- nents of general credibility, as conceptualized by Mc- Croskey and Young, 3,4 due to the specific dynamics involved in courtroom testimony. Existing research has already demonstrated the significant and curvi- linear relation of expert witness confidence to credi- bility. 6 Medium levels of witness confidence were rated as most credible, followed by high and then low levels of confidence. In this study, we sought to ex- amine the relation between expert witness likeability Dr. Brodsky is Professor of Psychology, and Ms. Neal, Mr. Cramer, and Mr. Ziemke are doctoral students in Psychiatry, The University of Albama, Tuscaloosa, AL. Address correspondence to: Stanley L. Brod- sky, PhD, University of Alabama, Box 870348, Tuscaloosa, AL 35487. E-mail: sbrodsky@bama.ua.edu 525 Volume 37, Number 4, 2009 REGULAR ARTICLE