Appearances can be deceiving: How naturalistic changes to target appearance impact on lineup-based decision making

The present study examined the influence of appearance, procedure and position on identification decisions, post-decisional confidence ratings and estimates of discrimination and confidence-specific accuracy. Regarding appearance, the study examined the combined influence of three naturalistic changes that occur day-to-day (i.e., a reduction in cranial hair length, the removal of stubble, and a change of clothing), two of which have not been considered before in a lineup-decision context. Participants (N = 350) completed four experimental lineups which involved: viewing a target person, completing a brief distractor task, and making an identification decision and a post-decisional confidence rating from a photographic lineup. Participants were randomly allocated to complete simultaneous or sequential lineups, with appearance (no change, change), position (early, late) and target (present, absent) systematically varied across the four trials. Appearance affected all dependent measures and was particularly influential in target present lineups. Naturalistic changes to target appearance reliably decreased correct identification rates, confidence in correct identifications, discrimination accuracy, and confidence-specific accuracy. Procedure and position, by contrast, had a more limited impact. Of concern for the criminal justice system, neither procedure nor position manipulations offset any reductions in lineup-decision accuracy when target appearance changed.