Improving Professional Observers’ Veracity Judgements by Tactical Interviewing

Understanding whether a person of interest is being truthful during an investigative interview is a constant challenge and is of concern to numerous criminal justice professionals, most of whom are not involved in conducting the interview itself. Here, we investigated police observers’ veracity detection performance having viewed interviews with truthtellers and deceivers using either the tactical use of evidence (TUE), strategic use of evidence (SUE) or a control technique. Thirty serving police officers participated as post-interview observers and each viewed 12 interviews in a counterbalanced order. After each interview, the officer made a veracity judgement. Overall, untrained police observers were significantly more accurate (68%) when making veracity judgements post - TUE interviews, whereas for both SUE and control performance was around chance (51% and 48%, respectively). Veracity performance for liars and truthtellers revealed a similar pattern of results (67% liars; 70% truthtellers) in the TUE condition. These results lend further support to the psychological literature highlighting the importance of how and when to reveal evidence or any other relevant event information during an investigative interview for ‘outing’ deceivers as well as allowing truthtellers early opportunities to demonstrate their innocence.