"It only tells you what the subject is feeling. It can't tell you why the subject felt it," Sejnowski said. If Roberts had given an expression of disgust when she was asked the question that would have been a normal reaction to the expression, too. Terrorists are trained to keep cool under pressure, but the system is sensitive enough to counter-act that.
"It's true — if you're a good actor, you can defeat any system — however, under pressure, even the best actors cannot prevent micro-expressions," Sejnowski said. "You might not even notice it, but the computer would be able to pick it up and thereby flag that this is an inappropriate reaction — even if they were highly trained."
If the device does spot troubled passengers in a terminal, they'd be red flagged and stopped before boarding a plane, he said. The project, which is funded by the National Science Foundation, is years away from being approved and set up in airports.