Like the rest of us, airport security screeners like to think they can read body language. The Transportation Security Administration has spent some $1 billion training thousands of “behavior detection officers” to look for facial expressions and other nonverbal clues that would identify terrorists.
But critics say there’s no evidence that these efforts have stopped a single terrorist or accomplished much beyond inconveniencing tens of thousands of passengers a year. The T.S.A. seems to have fallen for a classic form of self-deception: the belief that you can read liars’ minds by watching their bodies.