Partners in Crime: How Liars in Collusion Betray Themselves¹

The paradigmatic task for participants in studies on deception is to assess veracity on the basis of a single statement. However, in applied contexts, lie catchers are often faced with multiple statements (reported by one or several suspects). To appreciate this mismatch, we conducted a study where each member of 10 truth‐telling pairs and 10 lying pairs (reporting fabricated alibis) was interrogated twice about an alibi. As predicted, lying pair members were more consistent between themselves than were truth‐telling pair members, and single liars and truth tellers were equally consistent over time. Furthermore, truth tellers made more commissions than did liars. Although in line with our repeat vs. reconstruct hypothesis, these findings contrast sharply with beliefs held by professional lie catchers and recommendations found in literature on deception detection. The results are translated into an applied psycholegal context.