London, April 5 (ANI): Facial ticks that cause raised eyebrows and hints of a smile can give the game away when you lie, researchers say.
The team from the University of British Columbia, in Canada, found four facial muscles "leaked" a person's true feelings, such as guilt, amid intense emotional pressures.
They concluded that liars were betrayed by tiny movements that caused them to raise their eyebrows in surprised expressions and smile slightly.
Innocent people, meanwhile, tended to furrow their brow in genuine "expressions of distress", they found.
The study concluded that a person's lack of control over their facial expressions meant genuine feelings could be differentiated from fake emotion.
Psychologists say most humans can control lower face muscles in order to talk or eat but those in the upper face are difficult to manipulate and can spark involuntary behaviour.
Dr Leanne ten Brinke, who led the study, said the findings suggested attempts to mask our emotions are likely to fail when engaging in a "consequential act of deception".
"Our research suggests that muscles of the face are not under complete conscious control and certain muscles are likely to betray the liar, particularly in high-stakes and highly emotional situations," she told The Daily Telegraph.
"Facial cues are an important, but often ignored, aspect of credibility assessments where an emotional issue is in question.
"Cues to emotional deception are likely to occur when the underlying emotion a liar is attempting to mask, is relatively strong," she added.
The researchers analysed facial expressions of 52 people - half of whom were later proved to be lying - as they made emotional televised pleas for the safe return of a missing relative.
More than 23,000 frames of video were viewed from real-life cases in Britain, America, Canada and Australia.
Their study looked for emotional "leakage" from a person's muscles, which they found were harder to control during stressful events.
Dr ten Brinke, from the university's Centre for the Advancement of Psychological Science and Law (CAPSL), said the study found muscles "leaked" signs of true emotion because of the person's subconscious actions.
The team found that a "deceptive pleader" raised their forehead muscles, called the "frontalis", which gave off surprised expressions.
Liars also had increased activity of the "zygomatic major muscles", located around the mouth, which caused them to inadvertently lift their lips into a smile.
This compared to "genuine pleaders", who activated their inner frontalis and "corrugator supercilli", located between the eyebrows, which caused them to frown and furrow their brow in a genuine "an expression of distress".
"While genuine pleaders show real distress on their face, the deceptive pleaders are unable to replicate that same activation," Dr ten Brinke, who is based in the university's psychology department, added.
While the findings were important for "lie catchers", she cautioned they did not provide a "Pinocchio's nose".
She said: "Not everyone will leak their true emotions, and some people are better than others at adopting a false face (such as) psychopaths."
The study has been published in the journal Evolution and Human Behaviour. (ANI)
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