The USA Transportation Security Administration - which has spent US$1 billion training officers to look for nonverbal clues that would identify terrorists - has been told much of the money was wasted.
In experiments, law-enforcement officers and other presumed experts did no better than untrained persons.
"There's an illusion of insight that comes from looking at a person's body," said Nicholas Epley, a professor of behavioural science at the University of Chicago. "Body language speaks to us, but only in whispers."
In the studies, people correctly identified liars only 47 per cent of the time.
Accuracy was 61 per cent when it came to spotting truth tellers, but the overall average was 54 per cent, only slightly better than chance.
The accuracy was even lower when officers couldn't hear what was being said, and had to make a decision based on the person's body language.
The USA Transportation Security Administration - which has spent US$1 billion training officers to look for nonverbal clues that would identify terrorists - has been told much of the money was wasted.
In experiments, law-enforcement officers and other presumed experts did no better than untrained persons.
"There's an illusion of insight that comes from looking at a person's body," said Nicholas Epley, a professor of behavioural science at the University of Chicago. "Body language speaks to us, but only in whispers."
In the studies, people correctly identified liars only 47 per cent of the time.
Accuracy was 61 per cent when it came to spotting truth tellers, but the overall average was 54 per cent, only slightly better than chance.
The accuracy was even lower when officers couldn't hear what was being said, and had to make a decision based on the person's body language.
