Reading lies in real life is an active comparison from information we know for certain, and information told to us. No doubt, nonverbal language can provide clues to us as a full package, but it doesn’t permit us to ascertain conclusive evidence. We should therefore use untrustworthy or nervous body language as motivation to spark further investigation.
My advice to read people who want to detect liars is to watch for the little stuff, the microexpressions, the small gestures and the ones that happen instantly, and then hone in on further. Keep in mind too, that you won’t be able to detect lies much better than about seventy-five percent of the time anyway, which is on par with the CIA, minus of course various lie detection machines which are impractical and requiring cooperation that you are very unlikely to garner!
The top lie detectors all seem to have one trait in common, and that is skepticism. They know or assume that someone is lying and so view them through a skeptical eye. They are careful to watch and recall any cues that tip the scales toward deception. Looking at the world through rose-coloured glasses will lead to rose-coloured predictions about people, and this is all just dandy, and works for most people, but if you truly want to know the truth, you need to watch people more critically. You also must be aware of a person, from their face to their toes. If you’re goal is to make friends, then by all means avoid filtering and analyzing the body language around you. In fact, I would advise body language readers to relax their skills when around family and friends, or at least keep it a secret!
It is not safe to immediately peg someone a liar based on one or even a handful of cues just by the nature of the trade. Reading lying correctly is a long term comparison of the facts, the emotional body language, fear and stress, from one moment to the next, weighed against relaxed, neutral and contented body language. Success will come by looking at the full picture and comparing the parts to the whole and digging deeper when discrepancies happen between expressive behaviours and the words said. No doubt, lie detection is difficult, but with some body language, and knowledge of its limitations, your odds of success with significantly increase.