Watching for Nonverbal Cues Is Not
Despite popular belief, there are no consistent nonverbal
cues associated with lying (see, nonverbal cues).
The nonverbal cues that have been
identified vary widely from person to person, situation to situation, and according to the nature of the lie being told.
And when nonverbal cues have been identified – after looking at thousands of liars and
truth tellers - the findings cannot be applied to any given individual.
To begin with, most signs of lying occur too quickly to be seen with the naked eye. If deception
is revealed, it usually happens through micro expressions - briefly flashes of one's true emotional state (see, facial expression test).
More importantly, findings based on group averages cannot be applied to individuals.
For instance, if you know that smokers have a shorter lifespan than nonsmokers – and you know that I don’t
smoke – based on that information, can you tell when I’m going to die? Can you even tell me that I’m going
to live longer than most smokers? What if I were to die tomorrow?
lies the problem: statistics are great for describing groups, but you can’t use them to determine what any given individual
is going to do. Statistics taken from groups can only be applied to groups, not specific individuals. So, even though smokers
as a group will not live as long as non-smokers as a group, some smokers will live much longer than I will.
A recent new york times article on breast cancer does a much better job of making this point:
"...cancer doctors dislike applying statistics derived from huge
groups to individual patients. Some people do much better than average and some worse."
And the same holds true when it comes to detecting deception. If you see someone fidgeting while speaking, is that
person lying? Who knows? Liars as a group may fidget more when lying, but any given individual may fidget a lot more or a
lot less in any given situation.
The blog, 'truth, lies and romance', also provides a concrete example of the problems
encountered when trying to use group averages to identify what specific individuals are likely to do.
And to make matters even more complicated – the body language that people focus on the most – like breaking
eye contact – simply has nothing to do with lying.