Lying makes people nervous and that nervousness conveys itself in many different ways. The better you know someone, the easier it will be to tell if they are lying to you or telling the truth. That doesn't mean that you can't often guess at how truthful even a stranger is being when you talk to them, though. Most people have some involuntary gestures that they make when they're trying to mislead you.
- 'Shifty eyes'
Being unable to make or maintain eye contact is such a universal signal of deception that it's entered into the popular parlance. A 'shifty-eyed' person is one who is not to be trusted. If you want to impress someone with your sincerity, look them openly in the eye. If someone keeps looking away from you - especially up and to the right - they may be lying or concealing something.
- Touching the nose