Lie detection: Misconceptions, pitfalls, and opportunities for improvement

Unlike Pinocchio, liars do not usually give telltale signs that they are being dishonest. In lieu of a growing nose, is there a way to distinguish people who are telling the truth from those who aren’t? A new report in Psychological Science in the Public Interest, a journal of the Association for Psychological Science, discusses some of the common misconceptions about those proficient in the art of deception, reviews the shortcomings of commonly used lie-detection techniques, and presents new empirically supported methods for telling liars from truth-tellers with greater accuracy.

Trapping a liar is not always easy. Lies are often embedded in truths and behavioural differences between liars and truth-tellers are usually very small. In addition, some people are just very good at lying. Lie detectors routinely make the common mistakes of overemphasising nonverbal cues, neglecting intrapersonal variations (i.e. how a person acts when they are telling the truth versus when they are lying), and being overly confident in their lie-detection skills.

In this report, Aldert Vrij of the University of Portsmouth, Anders Granhag of the University of Gothenburg, and Stephen Porter of the University of British Columbia review research suggesting that verbal methods of deception detection are more useful than nonverbal methods commonly believed to be effective, and that there are psychological differences between liars and truth-tellers that can be exploited in the search for the truth.

In an information-gathering interview suspects are asked to give detailed statements about their activities through open questions – for example, “What did you do yesterday between 3pm and 4pm?” This interview style encourages suspects to talk and allows for opportunities to identify inconsistencies between the answer and available evidence. Asking very specific questions that a suspect is unlikely to anticipate may also help in lie detection.

Lying can be more cognitively demanding than truth-telling – it requires more brain power to come up with a lie and keep track of it (e.g. who was told what) than it does to tell the truth. Imposing cognitive load on interviewees by asking them to recall the events in reverse order may also be useful in weeding out liars from those telling the truth.

This research has important implications in a variety of settings, including the courtroom, police interviews, and screening individuals with criminal intent, for instance, identifying potential terrorists.

(Source: Association for Psychological Science: Psychological Science in the Public Interest)