We lie for all kinds of reasons. It's almost instinctive for us to want to cover up wrongdoings and postpone undesirable consequences, which is why we should have some basic knowledge of lie detection to avoid being the victim of any scheme or fraud. Most liars unconsciously give themselves away with their body language. But they can do this in many different ways, so it helps to know the person a little in order to make out whether they're keeping the truth from you. The internet is full of advice on how to spot liars but, as learnbodylanguage.org warns, there is no fool-proof way to know when somebody is lying to you, even if they do provide clues. The guilt involved with lying makes most liars give themselves away with their body language. Liars tend to talk in a higher pitch and faster. They usually talk too much, as they don't feel comfortable with silence. They tend to overuse pauses or clear their throat often. A dry mouth, which causes people to lick their lips, can indicate they are under stress. Interestingly, people who use contractions like 'didn't' instead of 'did not' are more likely to be telling the truth. Also, some liars might use humour or sarcasm to hide the truth. Another subtle indicator someone is lying to you is - like the three wise monkeys who hear no evil, see no evil and speak no evil - how they touch their faces, or rub their mouths, ears or noses when they are straying from the truth. In the neuro-linguistic classic Frogs into Princes: Neuro-Linguistic Programming, authors Richard Bandler and John Grinder write that the position of a person's eyes can tell us what they are thinking. Either they are remembering information - an indicator they are telling the truth - or they are making up the information, which would mean they are lying. People organise their thoughts in three categories: images, sounds and other feelings. This information is stored in different parts of our brains and we can tell which part of the brain a person is accessing depending on where their eyes move. When asked a question, a 'normally organised' right-handed person looks (from your viewpoint): Up and to the left, which indicates imagining or making up images. Up and to the right, which indicates remembering images. To the left, which indicates creating sounds. To the right indicates remembering sounds. Down and left, which indicates recalling a smell, feeling or taste. Down and right, which indicates internal dialogue or talking to themselves. Before making any snap judgments, explore the reliability of these cues by testing them with your family and friends. Bear in mind the eye directions of a typical left-handed person will be completely opposite to those of a right-handed person. One of the best lie-detecting tricks, especially when you suspect someone is lying to your face, is to change the topic unexpectedly. A guilty person will follow suit, feeling they have been saved, while an innocent person will probably be confused and want to return to the topic you were originally discussing. Beware of being over-confident, however, as many studies have found that the more determined you are to detect dishonesty, the more likely you will be to make mistakes. Even more importantly, everything you think you have learned can be useless when you come up against a liar who believes their own lies. Habitual liars often give away no clues in their body language and can be very convincing. It's also worth bearing in mind that perhaps it's sometimes a good thing there's no guaranteed way to know if we're being lied to. Perhaps, after all, somebody is lying to you for your own good, because the truth would be too painful.