Evidently more than 3,000 TSA agents have been trained in these techniques made famous by Paul Ekman, a professor at the University of California Medical School in San Francisco. The Fox television show Lie to Me is based on his techniques in law enforcement. The basic tenets of these techniques is that a properly trained individual can recognize deception with 70% accuracy.
So far, it appears 1,700 arrests have been made based upon these visual screeners. This is 1% of the 232,000 people screened using the methods. And most of these arrests were for existing criminal charges unrelated to terrorism. Criticism of SPOT points out that flipping a coin and choosing which airline passengers to screen would produce similar results.
The conclusion the writer and many of the subjects she interviewed is that humans are just not good lie detectors. We don’t read facial cues as good as we think we do. Guessing someone’s intentions is just not something most of us do well.