The Weapon Focus Effect for Person Identifications and Descriptions: A Meta-analysis

Abstract

In many crimes involving a weapon, witnesses report difficulties remembering the face of the perpetrator. In the current meta-analysis, we synthesized tests of the hypothesis that the presence of a weapon during commission of a crime negatively affects an eyewitness’s ability to later identify or describe the perpetrator (weapon focus effect: WFE). There was no significant effect on correct identifications in target-present lineups, on false identifications in target-absent lineups, nor for overall correct identification decisions across target-present and target-absent lineups. However, for the accuracy of descriptions of the target a significant, medium size WFE was observed. Parallel analyses tested the notion that the unusualness of an object is responsible for the WFE. Unusualness similarly affected person descriptions but not identifications. Moderator analyses explored rival theoretical approaches and boundary conditions of the observed effects. Theoretical issues, in particular the role of stress and arousal along the timeline of encoding, consolidation and retrieval phase, as well as the role of expectancy violations are highlighted. Methodological issues like the importance of using both target-present and target-absent lineups, the measurement of description accuracy, the type of moderator analyses in meta-analyses, the role of publication bias, and stress in simulation studies in comparison with archival analyses of crime cases are discussed. Practical implications for experts testifying in court as well as for police investigations are outlined.