There are many ways in which a person’s body language can give you information about whether they are lying or not.

One of the biggest signs that a person is telling lies is that he avoids eye contact during conversation. He may also touch his face often, covering his mouth with his hand very often. Touching the nose is also said to be a sign of taking others’ attention to cover up lies. A person who is not telling the truth may be trying to make you focus on his actions rather than his words.

When a liar (说谎者) tells lies, his physical expression is often very stiff (僵硬的). If he is smiling as he speaks, only the mouth will move. A real smile naturally causes movement of the mouth, eyes, forehead, cheeks, and jaw.

The liar’s hand, leg and arm movements are toward his own body. He takes up little space. The person’s body language is closed off. Liars do not look relaxed, even though they may be trying to give the impression that they are.

When explaining something, a liar usually feels uncomfortable with pauses (停顿) or silences. The person may speak gently or in disordered words. A very skillful liar is able to speak directly and with confidence. In fact, some salespeople are best at this skill.

If you doubt someone is lying, change the topic of conversation suddenly. The liar will willingly change topics with you and become more relaxed. A person who is telling the truth will generally become confused by this sudden change. Another sign of someone telling a lie is yawning (哈欠) — the person may try and look as relaxed as possible, and yawing and stretching are ways of achieving this.

Mirroring body language is a way to bond and to build understanding, It is a powerful tool that we use without even knowing it.

The most obvious forms of mirroring are yawning and smiling. When you see someone yawn, you are likely to yawn immediately. Smiling is also pretty contagious—seeing a smiling person makes you want to smile too.

Mirroring body language is a nonverbal way to say “I am like you, I feel the same”. Research shows that people who experience the same feelings are likely to trust, understand and accept each other.

Women have the natural ability to pick up and understand body signals. Therefore, it is not surprising that a woman is more likely to mirror another woman than a man is to mirror another man. That's why women are regarded as better talkers, even if they might not really have more close friends.

It is interesting that when a man tries to mirror a woman's body language while she is talking, he may seem to her as caring, intelligent and attractive.

Mirroring body language is an excellent way to build trust and understanding quickly. If you want to set up a connection with a new person, mirror his or her gestures, sitting position, tone of voice and talking pace. This will make them feel that there is something about you that they like.

While mirroring body language gains you acceptance, you still need to take into consideration your relationship with the person you are mirroring. If you are in a lower social position and are mirroring the body language of your boss, he will view you as arrogant. However, if you want to defeat those who are trying to prove superior to you, mirroring their body language will help defeat them and change their position.