In two experiments, we tested the hypotheses that (a) the difference between liars and truth tellers will be greater when interviewees report their stories in reverse order than in chronological order, and (b) instructing interviewees to recall their stories in reverse order will facilitate detecting deception. In Experiment 1, 80 mock suspects told the truth or lied about a staged event and did or did not report their stories in reverse order. The reverse order interviews contained many more cues to deceit than the control interviews. In Experiment 2, 55 police officers watched a selection of the videotaped interviews of Experiment 1 and made veracity judgements. Requesting suspects to convey their stories in reverse order improved police observers' ability to detect deception and did not result in a response bias.

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.

Five decades of lie detection research have shown that people’s ability to detect deception by observing behavior and listening to speech is limited. The problem is that cues to deception are typically faint and unreliable. The aim for interviewers, therefore, is to ask questions that actively elicit and amplify verbal and nonverbal cues to deceit. We present an innovative lie detection perspective based on cognitive load, demonstrating that it is possible to ask questions that raise cognitive load more in liars than in truth tellers. This cognitive lie detection perspective consists of two approaches. The imposing-cognitive-load approach aims to make the interview setting more difficult for interviewees. We argue that this affects liars more than truth tellers, resulting in more, and more blatant, cues to deceit. The strategic-questioning approach examines different ways of questioning that elicit the most differential responses between truth tellers and liars.