Eyewitness confidence and mock juror decisions of guilt: A meta-analytic review.

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. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Improving the interpretation of verbal eyewitness confidence statements by distinguishing perceptions of certainty from those of accuracy.

When an eyewitness makes an identification from a lineup, police are also instructed to collect a verbal expression of confidence. This recommendation hinges on the assumption that evaluators will perceive confidence in the manner the witness intended. However, research has consistently shown that these interpretations can be biased by accompanying contextual information. For example, statements that reference facial features (e.g., "I'm very sure. I remember his eyes.") are perceived as less confident than when the statement is presented alone ("I'm very sure.") (featural justification effect). Additionally, perceptions of witness confidence are altered when the witness's identification (mis-)matches the police suspect in a lineup (prior knowledge). We find that the same underlying mechanism explains the bias induced by both featural justification (Experiments 1 and 2) and prior knowledge (Experiment 3) manipulations. Evaluators conflate their own beliefs about the accuracy of an identification with the witness's intended level of confidence. A simple warning that highlights the differences between confidence and accuracy eliminates the featural justification effect, but is less effective for mitigating the influence of prior knowledge. The key takeaway from this paper is that distinguishing perceptions of certainty from those of accuracy improves the interpretation of verbal confidence statements. (PsycInfo Database Record (c) 2022 APA, all rights reserved).