What Makes an Expert Persuasive? Examining the Influence of Relevant and Superficial Cues on Jurors’ Evaluation of Forensic Expert Credibility and Evidence Quality.

Ms Mariam Younan1, A/Prof Kristy Martire1

1University of New South Wales, Kensington, Sydney, Australia

Forensic expert evidence is an important aid in legal decision-making, admitted to assist with critical and often consequential legal matters, for example; whether a defendant is implicated in a charged crime. However, the quality of expert opinions varies widely, with casefiles from Innocence Projects showing that low-quality forensic expert evidence has been admitted to trials, believed by lay juries, and has contributed to wrongful convictions. Thus, it is important that jurors can differentiate the expert opinions that can be relied upon from those that should be ignored. Promisingly, recent research providing jurors with rich, normative information about expert evidence quality (i.e., the expert’s ability, experience, training, supporting evidence) has found that jurors are able to effectively distinguish between low- and high-quality evidence. However, this research does not factor into account superficial cues (i.e., likeability, gender) that jurors are often exposed to, and might unduly consider in their assessments of expert credibility. Using written and videoed mock trials, three studies examined the effect of expert attractiveness, gender, and likeability on jurors’ evaluation of expert evidence. The results collectively revealed that even in the presence of these superficial cues, jurors were still able distinguish low and high-quality evidence. Individually, attractiveness and gender did not affect jurors’ evaluation of expert persuasiveness and opinion quality. However, likeability did affect jurors’ expert evidence evaluation such that there was an observed penalisation of credibility to ‘unlikeable’ experts, irrespective of objective evidence quality. Practice and psycho-legal implications, and directions into other superficial cues and paradigms, are discussed.


Mariam is currently a Masters of Forensic Psychology/PhD Candidate at the University of New South Wales. Her PhD research examines the superficial cues that jurors rely upon when evaluating expert evidence and assesses their ability to differentiate various qualities of evidence in the face of these cues. She is also currently completing a psychology placement at NSW Justice and Forensic Mental Health Network, with the Community Forensic Mental Health Service.