(Photo Credit: Sergio Bertolini Via Flickr Creative Commons)
The body language of a liar is riddled with common myths and misconceptions. Most articles start with giving you information on how to spot lying and deception; however I feel addressing the myths first will help to combat the rise in their popularity. The most common myth is that liars look away from you (avert their gaze) when they are lying. This is a false belief, which can be backed up with 40 years of research. See following link for further details of this misunderstood aspect of deception.
What you will often find is that a liar will consciously engage in greater eye contact, because it is commonly (but mistakenly) believed that direct eye contact is a sign of truthfulness. Eye gaze is also related to many factors which have nothing to do with deception. For instance, people make less eye contact when they are embarrassed and make more eye contact when dealing with people of high status than low status. Additionally, people avoid eye contact with others who sit too close and some use eye gaze to emotionally manipulate. (Vrij, 2008) For these reasons, no tangible relationship exists between eye gaze and deception.
Another classic myth which has made its way into prominence is using eye direction to detect deceit. I conducted research on this belief and found that the vast majority of people I encountered had heard about the 'eye movement linked to deception' myth and worryingly most people believed that looking a certain way was a reliable sign of deception. Recent research, however, (2012) has comprehensively discredited this theory. See following link for full details.
Detecting deception via body language alone is fraught with difficulties. Research has suggested that truth tellers can often appear more nervous than a liar, which is a result of the emotion 'fear'. The panic a truth teller feels when they suspect their story is not being believed will arouse fear, which in turn will manifest into nervous energy and look suspicious to an unskilled lie catcher. Some skilled liars may successfully control their deceptive behaviour and speech which removes the chance to observe such cues. Also, what's interesting to note is that increased cognitive load (creative thinking) has shown to suppress behavioral animation. Liars want to make an honest impression on you and can attempt to control their deceptive behaviour accordingly. Truth tellers are not as weary of their behavior and can look more uncomfortable when challenged. Remember, you're looking for a decrease in movement if you suspect someone is lying about something complex.
However, despite the many popular myths associated with the body language of a liar, research has indicated that pitch of voice (higher), speech rate (slower), fake smiles (microexpressions), head movements (persuasive), immediacy (none immediate answers) and lack of plausibility are reliable signs of deceit, so long as they appear in a cluster, not singularly. But note, there is no cue akin to Pinocchio's nose in detecting the body language of a liar; meaning there is no singular guaranteed sign of deception. However, for more accuracy the lie spotter should focus their attention on the words of the liars, as these are the carriers of deceit. Analysing the statements of the liar is more effective than looking for non-verbal signs of deceit, due to either have an incorrect belief about what behavior the 'typical' liar shows, or being unable to interoperate the non-verbal behaviour on show, thus rendering an innocent person guilty.
For more information on narrative (statement) analysis please see links below for our interviews with statement analysis experts Mark McClish and John R. "Jack" Schafer.