Perception of line-up suggestiveness: Effects of identification outcome knowledge

Abstract

Research on the hindsight bias has shown that knowledge of an event outcome makes the observed outcome appear more predictable than it does in the absence of outcome knowledge. It was hypothesised that perceptions of the suggestiveness of a line-up would be similarly influenced by knowledge of a witness' identification decision, with a positive identification of the suspect increasing, and a negative non-identification decreasing, perceived suggestiveness. The ratings of undergraduate students (N = 50) in Experiment 1 showed the predicted influence of positive outcome, whereas negative outcome had no demonstrable influence. In contrast, Experiment 2, conducted with police trainees (N = 126) and with the line-up presented in the context of a criminal investigation, partially supported the predicted influence of negative, but not positive, outcome. The discrepant findings are discussed in terms of the cognitive mechanisms underlying the hindsight bias and the implications for real-life judgements of line-up suggestiveness. © 2010 John Wiley & Sons, Ltd.