An examination of the cognitive processes related to eyewitness lineup decisions

Given the magnitude of errors in the criminal justice system, it is vital to increase our capacity to predict when an eyewitness is likely to be accurate. The aim of this work was to examine cognitive processes important for correct lineup responses and to develop a theoretically-driven model of the relative strength of these processes and the interactions between them for predicting the likelihood of an accurate lineup decision. We used sleep to manipulate memory strength and assessed decision process objectively, using eye tracking, and subjectively, using a questionnaire. We then modelled the influence of memory strength and decision process on correct identifications in a target-present lineup (Experiment 1) and correct rejections in a target-absent lineup (Experiment 2). Our subjective measure of decision process was the only predictor of correct identifications. Memory strength and decision process predicted the likelihood of correct rejections, and did so largely independently from one another, but the subjective measure was the stronger predictor. Combining the data from both experiments suggested that decision processes mediate the relationship between memory strength and identification accuracy. These results can inform theories of how cognitive processes interact to influence lineup decisions.