In 2009, 22-year-old student Nicholas George was going through a checkpoint at Philadelphia International Airport when Transportation Security Administration agents pulled him aside. A search of his luggage turned up flashcards with English and Arabic words. George was handcuffed, detained for hours, and questioned by the FBI.

George had been singled out by behavior-detection officers—people trained in picking out gestures and facial expressions that supposedly betrayed malicious intentions—as part of a US program called Screening Passengers by Observation Technique or SPOT. But the officers were wrong in singling him out, and George was released without charge the same day.

As the incident may suggest, SPOT produced very little useful information throughout its decade-long history. And in light of the technique’s failures, some computer scientists have recently concluded a machine could do a better job with this task than humans. But the machine techniques they intend to use share a surprising history with SPOT’s training procedures. In fact, both can be traced back to the same man—Paul Ekman, now an emeritus professor of psychology at the University of California.