Effects of false-evidence ploys and expert testimony on jurors' verdicts, recommended sentences, and perceptions of confession evidence

Abstract

During interrogations, police may use false-evidence ploys or fabricated claims to convince suspects to confess. Mock jurors read trial materials containing interrogation transcripts with or without a false-evidence ploy and one of two expert witness conditions (present or absent). We examined jurors' verdicts, recommended sentences, and perceptions of the interrogation. Although factual evidence and the defendant's confession remained constant across conditions, false-evidence ploys led to fewer convictions and shorter sentences. Jurors also perceived interrogations with ploys as more deceptive and coercive. Expert testimony reduced convictions and increased interrogation deception and coercion ratings. Across ploy types, participants rated demeanor ploys as less deceptive and recommended longer sentences for confessors. Outcomes reveal important, previously unrecognized consequences of false-evidence ploys.