Differences in expert witness knowledge: do mock jurors notice and does it matter?

Area of Science:

• Forensic Psychology
• Legal Decision-Making

Background:

• Expert witness credibility is presumed to influence legal judgments.
• The specific impact of demonstrated expert knowledge on juror perceptions remains largely unexplored.

Purpose of the Study:

• To investigate how varying levels of demonstrated knowledge in forensic experts affect mock juror perceptions.
• To examine the influence of expert knowledge and gender on credibility, agreement, and sentencing in a mock trial.

Main Methods:

• A mock-trial experiment manipulated the knowledge level (low vs. high) of a forensic expert.
• Mock jurors' perceptions of expert credibility, agreement, and sentencing recommendations were recorded.
• Expert gender was analyzed as a potential moderating factor.

Main Results:

• Knowledge manipulation had statistically significant effects, but limited practical utility in predicting juror decisions.
• Contrary to hypotheses, higher expert knowledge did not increase credibility or agreement.
• The low-knowledge expert was perceived as more likeable than the high-knowledge expert, a paradoxical finding.

Conclusions:

• Expert knowledge level primarily influenced perceived expert likeability, not credibility or agreement.
• The findings challenge traditional assumptions about the direct relationship between expert knowledge and juror persuasion.
• Further research is needed to understand the complex interplay of expert characteristics and juror decision-making.