Forget the fidgety liar nervously blinking, scratching his nose and stroking the back of his head. Researchers have found that liars stay motionless and control their blinking as they try not to give anything away.
When liars do use their hands, they use extravagant movements to cover up their dishonesty, stretching out their arms or rhythmically jabbing the air to emphasise a point.
The findings are likely to be of interest to police, employers and suspicious spouses, who may wrongly interpret nervousness as dishonesty but miss more reliable indicators.
“There is a popular perception that things like scratching the nose, playing with the hair, increase with people lying,” said Dr Samantha Mann, a psychologist at Portsmouth University. “People expect liars to be nervous and shifty and to fidget more, but our research shows that is not the case.
“People who are lying have to think harder, and when we think harder we tend to be a lot stiller, with fewer movements, because we are concentrating harder.”
In the research, to be reported shortly in the Journal of Nonverbal Behavior, the academics from Portsmouth and universities in Italy looked for changes in seven categories of hand movements in 130 volunteers told to make a series of honest and dishonest statements.
Metaphoric gestures — such as a heart to show love or holding the hands apart to indicate size — occurred 25% more often when lying.
Emblematic gestures that give out a direct message — such as thumbs up for okay, or palms outstretched for “calm down” — are also used slightly more often by liars.
A typical emblematic gesture was used in April 2003 by Mohammed Saeed al-Sahaf, the Iraqi information minister nicknamed Comical Ali.
As Iraqi troops ran for cover from American shellfire, Sahaf stretched out his arms, palms held forward, and told reporters: “Baghdad is safe. The infidels are committing suicide by the hundreds on the gates of Baghdad. Don’t believe those liars. As our leader Saddam Hussein said, ‘God is grilling their stomachs in hell’.”
Another liar’s trick is the rhythmic gesture, as in 1998 when Bill Clinton jabbed the air with each word: “I did not have sexual relations with that woman, Miss Lewinsky.”
Liars use self-adaptor gestures — touching the nose, hair or other parts of the body — 15%-20% less than truth-tellers. They also point at people about 20% less.
Mann has carried out separate research on the behaviour of suspects in police interviews. She found that, when lying, participants paused more in their speech and blinked less frequently — 18.5 times a minute compared with 23.6 times when telling the truth. About 81% of suspects paused longer or blinked less when telling a lie.
Debunking another myth, she said liars were just as likely as an honest person to look a questioner in the eye.