George Orwell, Nineteen Eighty-Four, Part 1, Chapter 5:
He did not know how long she had been looking at him, but perhaps for as much as five minutes, and it was possible that his features had not been perfectly under control. It was terribly dangerous to let your thoughts wander when you were in any public place or within range of a telescreen. The smallest thing could give you away. A nervous tic, an unconscious look of anxiety, a habit of muttering to yourself — anything that carried with it the suggestion of abnormality, of having something to hide. In any case, to wear an improper expression on your face (to look incredulous when a victory was announced, for example) was itself a punishable offence. There was even a word for it in Newspeak: facecrime, it was called.
TSA officials will not reveal specific behaviors identified by the program — called SPOT (Screening Passengers by Observation Technique) — that are considered indicators of possible terrorist intent.
But a central task is to recognize microfacial expressions — a flash of feelings that in a fraction of a second reflects emotions such as fear, anger, surprise or contempt, said Carl Maccario, who helped start the program for TSA.
“In the SPOT program, we have a conversation with (passengers) and we ask them about their trip,” said Maccario from his office in Boston. “When someone lies or tries to be deceptive, … there are behavior cues that show it. … A brief flash of fear.”
(Seattle PI link via Ken MacLeod)