A confidence-credibility model of expert witness persuasion: Mediating effects and implications for trial consultation.

Abstract

Trial consultation is a quickly growing domain of professional practice for psychologists. Preparing expert witnesses to testify is just one prime example of practice options for consultants. A wealth of evidence shows that developing expert confidence and credibility are important goals for witness training. However, research has yet to articulate a list of testimony delivery skills needed to bolster perceptions of credibility and agreement with the expert. The present study advances expert credibility theory and trial consultation practice by empirically validating a confidence-credibility mediation model of expert witness persuasion. It is argued that this model, grounded in credibility and confidence theories, can be integrated with existing methods of witness preparation training.

Attorney beliefs concerning scientific evidence and expert witness credibility

“…McCroskey and Young (1981) identified two central domains of source credibility: competency and character. More recent work indicates that perceptions of expert witness credibility are comprised of expert trustworthiness, confidence, likeability, and knowledge (Brodsky et al, 2010;Cramer, DeCoster, Harris, Fletcher, & Brodsky, 2011). Moreover, perceptions of expert witness credibility are also influenced by various factors including believability and credentials (Brodsky et al, 2010;Shuman, Champagne, & Whitaker, 1996a,b;Shuman et al, 1996a,b).…”

“…For instance, social science and legal scholars alike (e.g., Brodsky, 1999;Cramer, Brodsky, & DeCoster, 2009;Slovenko, 1999) note that expert witness confidence is a prominent factor in jury decision making. Moreover, aspects of credibility such as confidence and likeability may be assessed through verbal and nonverbal cues (Brodsky, Neal, Cramer, and Ziemke, 2009;Cramer et al, 2011). However, research has indicated that effects of perceived credibility (overall and facets such as confidence) is dependent upon the legal decision and nature of the expert at hand (Champagne, Shuman, & Whitaker, 1992;Cramer et al, 2011;Rogers, Bagby, Crouch, & Cutler, 1990).…”

“…This list dovetails well with expert witness credibility theory (Brodsky et al, 2010), noting trustworthiness and knowledge do impact fact finder positions (e.g., Brodsky et al, 2010;Cramer et al, 2009). Moreover, attorney valuing of general expert characteristics of years of experience, content of testimony, and communication skills are supported by the literature of credible testimony (e.g., Boccaccini & Brodsky, 2002;Cramer et al, 2011;Neal & Brodsky, 2008). Notably, if attorneys continue to base expert selection on empirically-supported characteristics, they can potentially take the next step of enhancing modifiable expert characteristics (e.g., communication skills) through witness preparation.…”

“…Moreover, aspects of credibility such as confidence and likeability may be assessed through verbal and nonverbal cues (Brodsky, Neal, Cramer, and Ziemke, 2009;Cramer et al, 2011). However, research has indicated that effects of perceived credibility (overall and facets such as confidence) is dependent upon the legal decision and nature of the expert at hand (Champagne, Shuman, & Whitaker, 1992;Cramer et al, 2011;Rogers, Bagby, Crouch, & Cutler, 1990). One particular study found that mock jurors rate medium-and high-confidence witnesses highly in perceived credibility; however, the jurors found the medium-confidence witnesses to be more credible than the high-confidence witnesses .…”

Perceived Credibility of Character Witnesses: Implications for Trial Consultation

“…Research has consistently highlighted the importance of witness confidence across types of witnesses ranging from experts, to lay eyewitnesses, and even defendants (Boccaccini, Gordon, & Brodsky, 2005;Cramer, Brodsky, & DeCoster, 2009;Cramer, DeCoster, Harris, Fletcher, & Brodsky, 2011;Lindsay et al, 1989;Luus & Wells, 1994;Penrod & Cutler, 1995;Whitley & Greenberg, 1986). As such, it appears delivering testimony in an appropriately confident (yet not arrogant) and consistent manner, regardless of content, is more believable.…”