Camera footage and identification testimony undermine the availability of exculpatory alibi evidence

Abstract

The present field experiment investigated how alibi witnesses react when confronted with camera footage or identification testimony that incriminates an innocent suspect. Under the pretext of a problem-solving study, pairs of participants (N = 109) and confederates worked on an individual task with a dividing wall obstructing their view of each other. When the mobile phone of the experimenter was missing from an adjacent room at the end of the session, all participants confirmed that the confederate had not left the room. After several days, participants returned to the lab for a second session. They were asked to confirm their corroboration, orally and in writing, after learning that the confederate either had been identified from a photograph or was present on camera footage. A control group received no evidence. In this second session, written (but not oral) alibi corroboration was weaker in the incriminating evidence conditions (47%) than the no-evidence condition (81%), as hypothesized. Unexpectedly, corroboration was equally strong in the camera and identification evidence conditions. As expected, alibi corroboration was stronger in session 1 than in session 2 for both camera (89% and 31–46%) and identification evidence conditions (86% and 31–49%). The current findings provide first evidence that camera footage and eyewitness identification testimony can bear on the availability of exculpatory alibi evidence in court and emphasize the need to document incidents of evidence contamination.