When Should Evidence be Disclosed in an Interview with a Suspect? An Experiment with Mock-Suspects

Abstract

The question of whether to disclose evidence to a suspect early on, or later, in an interview is often of critical importance for police offi cers' interviewing strategies. To shed light on this issue, an experiment was conducted in which 95 participants each committed a mocktheft as a hidden 'witness' observed them. A statement from the witness was presented to them during a subsequent interview in which they were 'suspects'. The time at which this evidence was disclosed to participants, and the evidence strength, was manipulated. Each participant was randomly assigned to one of four conditions; Early Weak, Early Strong, Late Weak, or Late Strong. Both late evidence disclosure, and strong evidence, produced higher confession rates than did early disclosure or weak evidence, and late disclosure of weak evidence resulted in the withdrawal of most of the confessions which had previously been made.