UC San Diego

Objective

Recent work has established that high-confidence identifications (IDs) from a police lineup can provide compelling evidence of guilt. By contrast, when a witness rejects the lineup, it may offer only limited evidence of innocence. Moreover, confidence in a lineup rejection often provides little additional information beyond the rejection itself. Thus, although lineups are useful for incriminating the guilty, they are less useful for clearing the innocent of suspicion. Here, we test predictions from a signal-detection-based model of eyewitness ID to create a lineup that is capable of increasing information about innocence.

Hypotheses

Our model-based simulations suggest that high-confidence rejections should exonerate many more innocent suspects and do so with higher accuracy if, after a witness rejects a lineup but before they report their confidence, they are shown the suspect and asked, "How sure are you that this person is not the perpetrator?"

Method

Participants (N = 3,346) recruited from Amazon Mechanical Turk watched a 30-s mock-crime video of a perpetrator. Afterward, they were randomly assigned to lineup procedures using a 2 (standard control vs. reveal condition) × 2 (target present vs. target absent) design. A standard simultaneous lineup served as the control condition. The reveal condition was identical to the control condition except in cases of lineup rejection: When a lineup rejection occurred, the suspect appeared on the screen, and participants provided a confidence rating indicating their belief that the suspect was not the perpetrator.

Results

The reveal procedure increased both the accuracy and frequency of high-confidence rejections relative to the standard simultaneous lineup.

Conclusions

Collecting a confidence rating about the suspect after a lineup is rejected may make it possible to quickly clear innocent suspects of suspicion and reduce the amount of contact that innocent people have with the legal system. (PsycInfo Database Record (c) 2022 APA, all rights reserved).