Do Viewing Conditions Moderate the Effect of Biased Lineup Composition on Eyewitness Identifications?

Eyewitness misidentifications are among the leading causes of wrongful convictions, making it crucial to identify the factors that contribute to these errors (Wells et al., 2020). General impairment factors, such as poor viewing conditions, reduce overall identification accuracy. In contrast, suspect-bias factors, such as biased lineup composition, specifically increase the likelihood of misidentifying the suspect. According to applied lineup theory, general impairment factors exacerbate the effects of suspect-bias factors (Brewer & Wells, 2011). Charman and Wells (2006) suggested that when memory is weak, eyewitnesses rely more on non-memory-based strategies (e.g., relative comparisons between lineup members) and less on memory-based strategies (i.e., absolute judgments between each lineup member and the witness’s memory of the culprit) when making identification decisions. I tested whether poor viewing conditions (a general impairment factor) exacerbate the effect of lineup bias (a suspect-bias factor) on suspect identifications. I hypothesized that the effect of lineup bias on suspect identifications would be stronger under poor viewing conditions. Overall, there was no evidence of an interaction between viewing conditions and lineup bias for innocent suspect identifications, but biased lineups led to more innocent suspect identifications overall. For guilty suspects, I found a small interaction effect suggesting that lineup bias had a stronger influence under poor viewing conditions, unlike for innocent suspects. I discussed the need for future research to further examine this pattern and clarify the mechanisms driving these effects.