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Last Updated: Monday, 20 March 2006, 13:24 GMT
Liars 'too self aware to twitch'
Lie detector test
Liars use big gestures to cover their tracks, the study said.
The image of a twitchy nervous liar touching his nose and stroking his hair may itself be a lie, a study says.

Italian and British researchers found when people lied they tended to stay still as they were acutely aware their body language might give them away.

The team monitored 130 volunteers as they were asked to make a series of honest and dishonest statements.

The study, in Journal of Nonverbal Behaviour, found liars touched their noses 20% less than truth tellers.

People expect liars to be nervous and shifty and to fidget more, but our research shows that is not the case
Dr Samantha Mann

Psychologist Dr Samantha Mann, who co-authored the study, said there was a popular perception that when people lie they scratch their nose and play with their hair more.

These movements are known as self-adaptor gestures which serve to comfort a person feeling vulnerable or exposed.

Instead of giving into these urges, she claimed, liars tried very hard to stay still and were just as likely as an honest person to look the questioner in the eye.

She added: "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."

She added: "As soon as we know that we are lying we suddenly become very aware of our behaviour.

"Most people tend to refrain from making movements at all."

The team from the universities of Portsmouth and Bergamo in Italy, also looked for changes in seven categories of hand gestures in their volunteers.

Self-adapting gestures

They found liars literally went to huge lengths to cover their tracks, especially when they were challenged over whether they were telling the truth.

Those under strong suspicion used certain types of hand gestures more in order reinforce the point.

The use of metaphoric gestures - such as touching the heart to show love and or the holding of hands apart to indicate size - were used 25% more often when people lied.

Rhythmic gestures such as repeated pointing to emphasise statements were also used more often by liars.

However, the use of what body language experts refer to as "self-adapting gestures" such as striking the hair, nose or other parts of the body, were used those telling lies 15-20% less.

Dr Peter Bull, a psychologist who has looked into the link between deception and body language, said there was a popular misconception that if someone is touching their nose they are more likely to be lying.

He said: "There is no Pinocchio's nose of lying. It doesn't mean that if you touch your nose in a certain way you are lying.

"And if it did people would stop doing it."

He said there needed to be a much closer analysis of what the subjects were saying when they did certain types of gestures.

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