We hypothesised that the responses of pairs of liars would correspond less with each other than would responses of pairs of truth tellers, but only when the responses are given to unanticipated questions. Liars and truth tellers were interviewed individually about having had lunch together in a restaurant. The interviewer asked typical opening questions which we expected the liars to anticipate, followed by questions about spatial and/or temporal information which we expected suspects not to anticipate, and also a request to draw the layout of the restaurant. The results supported the hypothesis, and based on correspondence in responses to the unanticipated questions, up to 80% of liars and truth tellers could be correctly classified, particularly when assessing drawings.

Background.We examined the effect of a second interviewer's demeanour on cues to deception. We predicted that a supportive demeanour would be the most beneficial for eliciting verbal cues to deceit, as it would encourage truth tellers, but not liars, to say more. In addition, we examined the extent to which interviewees deliberately made eye contact with the interviewers. Liars take their credibility less for granted than truth tellers, and therefore have a greater drive to be convincing. Liars are thus more likely to monitor the interviewer to determine if the interviewer appears to believe them.

Purpose. To our knowledge this was the first experiment that examined response trends over the course of a Symptom Validity Test (SVT). We predicted that the guilty group would avoid being associated with potentially incriminating information, and that they would do this more at the beginning of the test than towards the end.Method. The 86 participants of the guilty group carried out an illegal activity in a room and were instructed to deny having been in that room in a subsequent interview. The 82 innocent participants had never been in that particular room. During the interview the guilty and innocent groups were exposed to a 12-item SVT.Results and Conclusion. As predicted, the guilty participants selected fewer correct (crime related) items than innocents, and this tendency to avoid selecting the correct items was the strongest during the first half of the SVT. The implications of the findings for using an SVT in real life are discussed.Claims of crime amnesia are common in the criminal justice system. Research suggests that somewhere between 20% and 30% of suspects claim to have no recollection of the crime in question

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 with the 'Same Interviewers' condition. 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. As predicted, differences between truth tellers and liars in terms of detail and repetition were most pronounced in the 'Changed Interviewers' condition. 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.

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.