So are there any reliable indicators of mendacity? Tics – fidgeting, stuttering – are mistakenly attributed to cheats across many societies (psychologist Charles Bond has noted this belief in 63 countries) without recourse to scientific proof. Ditto the avoidance of eye contact – dropping your inquisitor’s gaze is often given anecdotally as confirmation of guilt.
“Eye contact has been proven the least accurate thing to watch for,” says Stan Walters, author of The Truth About Lying. “Most reliable cues typically come from the voice, in specific, the words.” Professor Richard Wiseman of Hertfordshire University is the UK’s leading authority on the subject. He says that common sense is the lie-buster’s best weapon, and affirms that it is aural rather than visual clues that are key.
Wiseman’s 1994 experiment on Tomorrow’s World and BBC radio had 30,000 participants watching or listening to two interviews he conducted with Robin Day. In one, Day told the truth; in the other he lied. Viewers could not spot the lie: there was a near-50/50 vote. Radio listeners, however, achieved over 70 per cent accuracy.
“Lying taxes the mind,” Wiseman explains. “It involves thinking about what is plausible. People tend to repeat phrases, give shorter answers, and hesitate more. They will try to distance themselves from the lie, so use far more impersonal language. Liars often reduce the number of times that they say words like ‘I’, ‘me’, and ‘mine’. To detect deception, look for aural signs associated with having to think hard.”
According to the Canadian Journal of Police and Security Services, another side-effect of lying that forensic interrogators will look for is the avoidance of verbal contractions – using “I am” instead of “I’m” and so on. Nature reported another study by Ioannis Pavlidis of Honeywell Laboratories in Minnesota. He established that many people blush when they are telling a lie – a subtle, but detectable, phenomenon. Pavlidis has developed a thermal-imaging technique that he says detects deceit by recording thermal patterns in people’s faces. He’s shown this technique to have an accuracy rate comparable to that of polygraph examination by experts, and says his method has vast potential for application in rapid or remote security screening (at airports and border crossings, for example), without the need for skilled staff or physical contact.
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