How Witnesses’ Perceptions of Identification Decision Consequences Affect Their Choosing Patterns

Author: Carmen Lucas

Lucas, Carmen, 2017 How Witnesses’ Perceptions of Identification Decision Consequences Affect Their Choosing Patterns, Flinders University, School of Psychology

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This thesis describes five experiments that aimed to manipulate people’s perceptions about the consequences associated with eyewitness identification decisions and test whether this affected their subsequent willingness to choose from a lineup. If consequence perceptions influence identification decisions, a serious applied problem arises. Due to the complexity of a criminal investigation people’s consequence judgements are undoubtedly highly subjective and, therefore, potentially form a misguided basis for choosing from or rejecting the lineup. While there are both intuitive and theoretical grounds for thinking that identification decisions are influenced by perceptions regarding the associated consequences, only one experiment (to my knowledge) has been previously conducted to address this possibility, with inconclusive results. The lack of research in this area may be, at least in part, due to the fact that there are significant ethical and methodological obstacles associated with researching identification decisions in a context where people think that their decisions have meaningful repercussions. However, prompting people to consider the consequences of an identification decision in a laboratory context may provide an adequate paradigm for beginning to develop an understanding of this issue. Therefore, the experiments comprising this thesis implemented a hypothetical consequences paradigm to investigate the issue.

Information about the likelihood that mistakenly choosing from or rejecting a lineup could result in the worst case scenario (i.e., a wrongful conviction or the guilty party getting away) was used as the primary means to manipulate people’s consequence perceptions—with the aim of influencing which mistake people thought would be worse to make. It was hypothesised that those who were led to believe that mistakenly rejecting a lineup is worse than mistakenly choosing from a lineup would be more likely to make positive identification decisions than those who were led to think the opposite, with the result being higher target-present and lower target-absent accuracy for the former. The results from the first four experiments showed no difference in choosing (or accuracy) between the two consequence likelihood conditions. However, each provided a step forward in refining the manipulation of consequence perceptions and testing their influence in a hypothetical context. The fifth and final experiment showed a small significant difference in choosing, in the predicted direction. This difference translated into the hypothesised differences in accuracy for target-present and target-absent lineups. Moreover, descriptive evidence was obtained to suggest that the effect of perceived consequence likelihood on identification decisions was greater for people who were not very confident in which decision to make. These experiments form a basis for delineating the conditions under which hypothetical consequences might be reliably shown to bias identification decisions in future research. The theoretical and applied implications of the findings for the likely influence of consequences perceptions on actual identification decisions is discussed, along with potential future directions for research in this area.

Keywords: Eyewitness identification, hypothetical consequences, consequence perceptions, choosing bias

Subject: Psychology thesis

Thesis type: Doctor of Philosophy
Completed: 2017
School: School of Psychology
Supervisor: Neil Brewer