On the cognitive processes underlying the verbal overshadowing effect: Culprit descriptions reduce culprit-presence detection and guessing-based selection in eyewitness responses to lineups

Purpose

Culprit descriptions by eyewitnesses and eyewitness responses to lineups are essential for criminal investigations—the former to locate possible suspects and the latter to provide information relevant to determining guilt or innocence. However, describing a culprit before responding to a lineup can reduce culprit identification rates, a phenomenon known as the verbal overshadowing effect. The well-validated two-high threshold (2-HT) eyewitness identification model was applied to investigate how providing culprit descriptions affects the cognitive processes underlying the observable lineup responses and, thus, to determine which changes in cognitive processes underlie the verbal overshadowing effect.

Methods

Participants watched a staged-crime video with four culprits. Subsequently, participants either described or did not describe the culprits before responding to four lineups. Two of the lineups were culprit-present lineups; two were culprit-absent lineups.

Results

Compared to the no-culprit-description condition, providing culprit descriptions reduced both the probability of culprit-presence detection and the probability of guessing-based selection.

Conclusion

The findings demonstrate that the verbal overshadowing effect is driven by changes in two distinct underlying processes: Describing a culprit interferes with face recognition and makes eyewitnesses more reluctant to select someone from the lineup based on guessing.