Evaluators' Perceptions of Suspect-Bias Variables

Evaluators of eyewitness evidence (e.g., judges, jurors) often must determine whether an eyewitness’s identification of a police suspect is accurate or mistaken. It has recently been argued that a particular class of variables—suspect-bias variables—pose a unique threat to the reliability of eyewitness identification evidence. Unlike “general impairment” variables that generally impair eyewitness identification accuracy (e.g., poor viewing conditions, biased lineup instructions), suspect-bias variables produce a suspect-specific bias that increases the risk of confident misidentifications of innocent suspects. The goal of this research was to examine evaluators’ sensitivity to suspect-bias variables compared to general impairment variables, and to test whether sensitivity to suspect-bias differs as a function of whether the suspect-bias variable is under the control of the legal system (system suspect-bias) or outside of the legal system’s control (estimator suspect-bias). Participant-evaluators (N = 214) read eight crime vignettes paired with one of four different eyewitness variables (system suspect-bias, estimator suspect-bias, general impairment, or no-variable control) and rated the accuracy of each eyewitness. Evaluators also explained the reasoning for their accuracy rating, and their explanations were coded for mentions of procedural suggestion, eyewitness memory strength, memory contamination, and general eyewitness (un)reliability. Evaluators appear to be more sensitive to general impairment variables than to suspect-bias variables. This finding is alarming, as suspect-bias variables pose a greater threat to eyewitness reliability than general-impairment variables. Implications for the collection and evaluation of eyewitness evidence are discussed.