1. Consider the person's recall: Liars never forget what they have to say but they may stumble when telling a tale by making contradicting statements. They're also eager to change the subject.
2. Observe the person's overall body language: Liars can look ill at ease, fiddling with their hair, stroking their throat, or rubbing their eyes. With their body often turned away from you, you may notice hand or leg fidgeting. Liars also have trouble swallowing and may shake their heads after a point has been made. When the subject finally gets changed, they appear happier and more comfortable, maybe laughing nervously.
3.Take notice of any defensiveness: Liars will often take offence to any indication that they're under suspicion. They're likely to throw any accusations you throw at them back at you. They will also talk too much, feeling the need to over-explain themselves
4. Home in on facial expressions: Liars fail to control their micro-expressions. While fibbing, you may notice nervous twitching. Their hand may be covering or touching their face. People also tend to touch the mouth when feeling guilty or anxious. They're particularly good with fake smiles.
5. Don't overlook the Pinocchio reaction: When a human tells a lie, extra blood gets pumped through the body and the nose swells by a fraction of millimeter. Liars may subsequently touch the tip of their nose unconsciously.
6. Concentrate on the eyes: A liar has a troubled brow and downcast or darting eyes. They have trouble directly engaging your gaze. They also give you eye-accessing clues. If the person is telling you the truth, he'll look up and to the left since that's the side of the brain we use for recalling information. If she's lying, she'll look up and to the right, which is the creative side of the brain, because she's mentally constructing something that hasn't happened.
7. Note the person's voice: The higher the stakes are, the more the liar has a fear of getting caught. With this, the liar has a harder time controlling his body language or her voice. The pitch or rate of the speech may change, with the individual giving a lot of "umms" and "ahhs." Often, a liar will appear stilted and monotone.