Saturday, June 30, 2012
To know if someone is telling the truth, keep an eye on the eyes.
Liars blink in different ways during and after a falsehood, researchers claim.
They blink less than normal during the lie, and then have a flurry up to eight times faster than usual afterwards.
'It is striking what different patterns in eye blinks emerged for liars and truth tellers,' said Dr Sharon Leal, co-author of the study at Portsmouth University.
'Such striking differences in behaviour between liars and truth tellers are rarely seen in deception research.'
The psychologists say that the discovery, reported in the Journal of Non-verbal Behaviour, means that blink rates could be used by professionals to catch liars.
In the study, a group of volunteers were told to go about their normal business for ten minutes but not to do anything that they might later have to lie about.
A second group were asked to steal an exam paper from an office, then to deny having taken it.
Experimenters, unaware of which group each individual was attached to, then asked each to recall exactly what they had been doing.
While they were being asked questions, their blink rates, which had all been the same at the start, were monitored with electrodes placed above and below and at the sides of the eyes to monitor all movements.
Results show that when the questions were being asked and the answers given, the blink rate in the liars went down.
The truth tellers' rate went up, possibly because of test anxiety.
Afterwards, the blink rate of the liars increased rapidly in a sudden flurry of activity, while that of the truth tellers remained the same.
The researchers say that the increased mental effort involved in telling fibs could be the reason why liars do not blink during the act of lying.
Dr Leal said: 'Liars must need to make up their stories and must monitor their fabrication so that they are plausible and adhere to everything the observer knows or might find out.
'In addition, liars must remember their earlier statements, so that they appear consistent when re-telling their story, and know what they told to whom. Liars will be more inclined than truth tellers to monitor and control their demeanour so they will appear honest.
'The reasons why there is a flurry of blinks after the lie is not really clear. It may be that this flurry is a kind of safety valve, like a release of energy after the tension of lying.'
Read more: http://www.dailymail.co.uk/sciencetech/article-1047130/How-spot-lie-Its-blinking-obvious-.html#ixzz1arXBtsBi