Eyewitness Confidence and Mock Juror Decisions of Guilt: A Meta-Analytic Review

Abstract

Objective: We investigated the impact of eyewitness confidence on the following dependent variables: (a) guilty or not-guilty verdict; (b) judgments of guilt as measured on a scale; and (c) mock jurors’ perception of the accuracy of an eyewitness’s identification. In addition, we examined two potential moderators of the effects of eyewitness confidence: (a) whether the eyewitness expressed confidence at trial versus during the initial lineup identification and (b) whether the eyewitness provided a numerical versus a verbal statement of confidence. Hypotheses: We expected all analyses to reveal that highly confident eyewitnesses are more persuasive to mock jurors than are eyewitnesses with lower confidence (Hypothesis 1). We expected eyewitness confidence at trial (relative to at identification) to be more persuasive to mock jurors (Hypothesis 2). We expected numerical expressions of confidence to be more persuasive to mock jurors than verbal confidence expressions (Hypothesis 3). Method: We conducted a meta-analysis of 35 studies from 20 published papers and seven theses or dissertations to quantify the effect of eyewitness confidence on juror judgments and investigated the influence of two primary moderator variables, time of confidence and format of confidence expression. Results: All analyses revealed an effect of eyewitness confidence on mock juror decisions (gs =.21–.36). Our moderator analysis showed that the timing of the confidence statement (identification vs. trial) did not affect the influence of eyewitness confidence on mock jurors’ judgments of guilt or accuracy. The influence of eyewitness confidence was not moderated by verbal versus numerical expressions of confidence. Conclusions: Although eyewitness confidence is persuasive to mock jurors, the size of this effect is modest. Moreover, verbal and numerical expressions of confidence have similar persuasive effects, and mock jurors do not appear to be sensitive to the likely difference in evidentiary strength of eyewitness confidence expressed at the initial identification versus at trial.