IN PUBLIC LIFE, accusations of lying are commonplace. A politician who lies is deemed guilty of a serious moral lapse. In private life, someone who lies to their partner is thought to have breached their trust.

Yet we have double standards about lying. Social psychologists point out that telling white lies enables us to function in a cohesive society. At the same time emphasis is placed on work aimed at uncovering liars, particularly in cases of crime or where public office is held.

Children begin lying at the age of three or four, in line with their developing sense of self-consciousness. By seven or eight, their lying becomes more adept as verbal fluency increases. But research by Dr Sean Spence, a reader in psychiatry at the University of Sheffield, indicates that we are programmed to tell the truth. He asked subjects to tell lies and simultaneously scanned them to see which parts of the brain were activated. Whenever they lied, the same regions of the prefrontal cortex lit up. Spence explains: “The areas of the brain that were engaged suppress automatic responses, such as aggression, which are inappropriate.”

Lying may be the mark of sophistication and intelligence — but it takes an effort to lie. The brain has to suppress the instinct to tell the truth. Freudians regard the onset of lying as important. “The notion is that in order to have an independent life, you have to grasp that you know things that others don’t,” Spence says.

Good liars, he suggests, will be verbally fluent, have a good working memory and be able to control their physical responses to some extent. If lying is so difficult, why do we do so much of it? “It’s easy to see why lying is advantageous,” he says. “We may want to keep information from others — information is power — or spread disinformation.”

Few of us tell the truth all the time and yet we are bad at spotting liars. “The stereotypes are incorrect,” Spence says. “We think liars avoid eye contact because they are embarrassed and use their hands more. The neurolinguistic view is that when people are searching for information, their eyes will naturally move in different directions. Behavioural studies suggest that, when lying, body language is reduced.”

For instance, his advice to police interviewing suspects is to sit well back and observe overall body language.

Derren Brown is a magician who has built a career partly from his facility for identifying liars. He features in a forthcoming BBC Radio 4 series on lying, Pants on Fire, in which he repeatedly foils the presenter Martin Plimmer’s efforts to lie to him.

Brown looks for what he calls a “truth pattern” and watches for how it is broken. “If I ask what you had for dinner, your eyes will go up and to the left to remember. If I ask you about something that hasn’t happened, your eyes will go somewhere else. Someone may keep eye contact when lying because they think people break eye contact when lying. But your eyes have to move away to find information.”

Other clues used by Brown hark back to Spence’s finding that telling the truth is a primary force. Brown says: “We do myriad things to stop the lie coming out. It’s as though the body doesn’t like lying. We do things, such as pausing, swallowing or putting a hand to the face, to keep the words in.”

Paul Ekman, a professor of psychology at the University of California Medical School, has developed a method of identifying the facial signs that betray a lie. He has worked with law-enforcement agencies and has studied the faces of spies, assassins, embezzlers, murderers and leaders.

Bill Clinton, he says, was “a ghastly liar”, who used “distancing language”, for instance, referring to Monica Lewinsky as “that woman”. Dr Harold Shipman, the serial killer, is a good liar, Ekman says. “There is no sign of lying in his demeanour, no twitch in the muscles or change in the voice.”

Ekman’s facial-action coding system measures fast facial movements lasting less than a fifth of a second. “They are an important source of leakage, revealing an emotion a person is trying to conceal,” he explains. “A false expression can be betrayed in several ways: it is usually slightly asymmetrical and lacks smoothness in the way it flows on and off the face.”