‘We'll take it from here’: the effect of changing interviewers in information gathering interviews

Background. A common strategy in interviewing is to repeatedly focus on the same topics, for example by asking to recall an event first in chronological order and then in reverse order. We examined the effect of changing interviewers between the two questions or keeping the same interviewers throughout on cues to deception. Truth tellers may be most encouraged to recall again what they have witnessed when confronted with new interviewers, as these new interviewers have not heard their story before. Liars may be most encouraged to recall again their story when confronted with the same interviewers, realising that these interviewers will check for consistency in their answers. The impact of changing interviewers should lead to more pronounced differences between truth tellers and liars in terms of detail and repetition in the ‘Changed Interviewers’ condition compared to the ‘Same Interviewers’ condition.
Method. Participants were interviewed by two interviewers about a mock security meeting they attended. In half the interviews the same two interviewers remained throughout, and in the other half two new interviewers took over half-way through.
Results. As predicted, differences between truth tellers and liars in terms of detail and repetition were most pronounced in the ‘Changed Interviewers’ condition.
Conclusions. Changing interviewers during an interview effectively differentiates liars and truth tellers with respect to detail and repetition. We discuss this finding and its place within investigative interviewing and deception detection literature.