“Liar, liar pants on fire.” Many of us have longed to scream this at a co-worker at one time or another — and it’s not surprising, considering that we’re up against an estimated 200 fibs a day.

A lot of these lies are harmless, says Paul Seager, a psychologist and co-author of Would I Lie to You? (Fusion Press, £10.99). “White lies are the oil that keeps life’s machinery running smoothly,” he says. “If someone says they like your new hairstyle and really they don’t, it’s of no benefit to spot their lie.”

On the other hand, there are times when you need to know if someone is telling the truth — if he has been committing fraud, for example, or doesn’t have the qualifications or experience that he claims to have. Research last year by the Risk Advisory Group on 3,800 CVs used in job applications revealed that more than half of them contained lies, including fictitious qualifications and undeclared county court judgments.

So how can you tell if someone is lying? Seager advises ignoring all stereotypical ideas about how liars act. He says that indicators such as lack of eye contact and nervous shifting are unreliable, and instead offers these pointers:

Catch people unawares with a question and note how quickly they respond. The longer it takes, the more likely that it’s a lie.

Raise the stakes. “Make it as emotional as you can. If you say ‘If you lie and get caught, you’re fired’ the stakes are higher and liars generally give more away.”

Ask a question that requires a yes-or-no answer, and repeat it until you get one. “Liars generally don’t give yes-or-no answers. They hedge their bets and give nebulous answers.”

Watch for a lack of arm movements. The thought required for lying uses a lot of energy, which is diverted from other areas of the body. So, contrary to conventional wisdom, liars may move around less, not more, than other people.

Measure the person’s response against their normal behaviour. If you know how she is normally, you may spot a telltale difference.

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