The confidence-accuracy relationship for eyewitness reports

Abstract

Legal decision makers tend to believe that highly confident witnesses are more accurate than less confident witnesses. Furthermore, research suggests that confidence judgements can provide a useful indicator of the accuracy of witnesses’ identification decisions. Yet little research has examined the relationship between eyewitness confidence and accuracy when witnesses recall details about a crime. The experiments in this thesis therefore aimed to examine the factors that influence the relationship between the accuracy of witnesses’ memory reports and their confidence in those reports, and to further our understanding of how witnesses make confidence judgements. Part One of this thesis examines several factors that may affect the relationship between confidence and accuracy when witnesses report their memories of a crime. The results of Experiments 1-3 indicate that witnesses’ confidence judgements can provide a useful indicator of their memory accuracy regardless of whether they are collected immediately after each response or at the end of the memory test. Experiment 1 also indicates that the confidence-accuracy relationship can remain strong when memory performance is impaired by poor visibility, but Experiment 2 suggests that the relationship between confidence and accuracy breaks down when witnesses are exposed to misinformation. Experiment 4 explores the effect of retention interval and self-rated memory ability on the confidence-accuracy relationship. The results suggest that relatively long retention intervals can impair the confidence-accuracy relationship, but people’s perception of their everyday memory ability has little impact on the confidence-accuracy relationship. Part Two examines the confidence-accuracy relationship in the context of cross-examination. The findings suggest that the effect of cross-examination style questions on eyewitness accuracy depends on the question type and eyewitness confidence. Together, the findings presented in this thesis help to refine theories of eyewitness confidence and highlight potential issues for using confidence judgements to assess eyewitness accuracy in real cases