Juror decision making: Does expert testimony produce improved accuracy when an eyewitness is confident?

Abstract

This study was an experiment comparing participant responses to a mock trial script including confident eyewitness testimony (that was either supported or contradicted by the mock trial evidence presented in the script) with, and without, expert testimony on the accuracy of eyewitness reports and memory errors. The researcher hypothesized that mock jurors exposed to expert testimony on the limitations of eyewitness accounts would be less likely to convict when faced with an eyewitness statement that was inconsistent with the presented trial facts. 156 participants recruited from Amazon Mechanical Turk were included in the final analyses. While the evidence did not support the eyewitness testimony, there was a significant difference (p .10) between the groups, (2 [1, N = 83] = 3.44, p = 0.063, Cramer’s V = .20) with those exposed to the expert testimony choosing to convict at a rate 20% higher than those not exposed to the expert. Not only did the jurors exposed to expert witness testimony and trial facts inconsistent with eyewitness testimony not convict less than their counterparts, but the jurors in this designated group also convicted at a higher percentage than all of the other groups. There is a gap in our field when it comes to educating our jurors about eyewitness errors. Researchers have to find a way to close the gap between academia and jurors in order to help those at the mercy of the law.