Travelers at Sea-Tac and dozens of other major airports across America are being scrutinized by teams of TSA behavior-detection officers specially trained to discern the subtlest suspicious behaviors.
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."
Such people are referred for secondary screening, which can include a pat-down search and an X-ray exam. The microfacial expressions, he said, are the same across many cultures.