Criterial Variability in Eyewitness Identifications

Abstract

Lineups typically induce superior performance compared to one-person identification procedures or showups. Understanding what makes the lineup a superior procedure is important to reduce identification errors, as these can lead to wrongful convictions. Differential filler siphoning, diagnostic feature detection, and criterial variability each attempt to explain lineup superiority. We test the hypothesis that the accuracy of an identification is impacted by group-level variability in criterion placement. Experiment 1 showed greater variability in criterion placement in the showup condition, although overall performance was not worse than the lineup condition. Experiment 2 used different photos of faces from study to test and introduced a constrained showup condition designed to lessen criterial variability by having participants respond only when they are highly confident. Experiment 3 introduced a simultaneous showup condition as another way to help participants set their criterion less variably by making diagnostic information more accessible. We replicate the finding that people set their criterion more variably in showups compared to lineups in Experiments 1 and 2, but this does not translate to a discriminability difference. Experiment 3 results are inconclusive, but this could be due to a small sample size. Therefore, more data are needed to attribute discriminability differences to criterial variability.