Mock-Juror Evaluations of Traditional and Ratings-Based Eyewitness Identification Evidence
Compared to categorical identifications, culprit likelihood ratings (having the witness rate, for each lineup member, the likelihood that the individual is the culprit) provide a promising alternative for assessing a suspect’s likely guilt. Four experiments addressed 2 broad questions about the use of culprit likelihood ratings evidence by mock-jurors. First, are mock-jurors receptive to noncategorical forms of identification evidence? Second, does the additional information provided by ratings (relating to discrimination) affect jurors’ evaluations of the identification evidence? Experiments 1 and 1A manipulated confidence (90% vs. 50%) and discrimination (good, poor, no information) between participants. Evaluations were influenced by confidence, but not discrimination. However, a within-participant manipulation of discrimination (Experiment 2) demonstrated that evidence of good discrimination enhanced the persuasiveness of moderate levels of confidence, while poor discrimination reduced the persuasiveness of high levels of confidence. Thus, participants can interpret ratings-based evidence, but may not intuit the discrimination information when evaluating ratings for a single identification procedure. Providing detailed instructions about interpreting ratings produced clear discrimination effects when evaluating a single identification procedure (Experiment 3). Across 4 experiments, we found no evidence that mock-jurors perceived noncategorical identification evidence to be less informative than categorical evidence. However, jurors will likely benefit from instruction when interpreting ratings provided by a single witness.