Translating theory into practice: Evaluating a cognitive lie detection training workshop

• A cognitive lie detection training improved trainees’ ability to distinguish truth tellers from liars.
• A cognitive lie detection training improved the percentage of appropriate questions the trainees asked.
• Trainees often thought they had used techniques taught in the training when, in fact, they did not do this.
• Trainees’ questions did not elicit differences in detail between truth tellers and liars.

A training workshop utilising the most up to date research in cognitive lie detection was designed and evaluated. For this evaluation, 27 experienced police detectives each interviewed one mock-suspect (a truth teller or liar) before training and another mock-suspect (a truth teller or liar) after training. Different mock-crimes were used in the pre- and post training interviews. The police detectives were free to interview the mock-suspect in any way they felt appropriate but were asked to try to incorporate (some of) the taught techniques in the post-training interviews. The detectives made veracity judgements and the interviews were transcribed and coded for the amount of detail elicited and the questions asked. Trainees’ ability to distinguish truth tellers from liars improved, and so did the percentage of appropriate questions they asked. Trainees did not implement the taught techniques to an equal extent, but when they were used, the techniques enhanced the elicitation of information and discrimination between truth tellers and liars. The training study also revealed challenges, particularly difficulty in implementing the taught techniques into practice (detectives often thought they had used techniques taught in the training when they in fact not used them as they had been shown to do) and asking the right questions to elicit differences in detail between truth tellers and liars.