Collective interviewing of suspects

When people are interviewed about possible wrongdoing that has been committed in groups, they typically are interviewed separately. Yet, in several settings it would be more intuitive and convenient to interview suspects together. Importantly, such collective interviews could yield verbal cues to deception. This is the first deception experiment to investigate collective interviewing. Twenty-one pairs of truth tellers and 22 pairs of liars were interviewed pair-wise about having had lunch together in a restaurant. Given that truth tellers adopt a “tell it all” strategy in the interviews while, in contrast, liars prefer to keep their stories simple, we predicted that pairs of truth tellers would (i) interrupt and (ii) correct each other more, and would (iii) add more information to each other's answers than pairs of liars. The results supported these hypotheses. Theory-driven interventions to elicit more cues to deception through simultaneous interviewing are discussed.