The Effects of Mock Jurors’ Beliefs About Eyewitness Performance on Trial Judgments

Two experiments examined how mock jurors’ beliefs about three factors known to influence eyewitness memory accuracy relate to decision-making (age of eyewitness and presence of weapon in Study 1, length of eyewitness identification decision time in Study 2). Psychology undergraduates rendered verdicts and evaluated trial participants after reading a robbery-murder trial summary that varied eyewitness age (6, 11, 42, or 74 years) and weapon presence (visible or not) in Study 1 and eyewitness decision length (2-3 or 30 seconds) in Study 2 (n=200 each). The interactions between participant belief about these variables and the manipulated variables themselves were the heart of this study. Participants’ beliefs about eyewitness age and weapon presence interacted with these manipulations, but only for some judgments – verdict for eyewitness age and eyewitness credibility for weapon focus. The exploratory meditational analyses found only one relation: juror belief about eyewitness age mediated the relation between eyewitness age and credibility ratings. These results highlight a need for juror education and specialized voir dire in cases where legitimate concerns exist regarding the reliability of eyewitness memory (e.g., child eyewitness, weapon presence during event, long eyewitness identification time). If erroneous juror beliefs can be corrected their impact may be reduced.