Telling a white lie at dinner may save a friend some hurt feelings, but prevaricating in a murder case or terrorism investigation has serious, far reaching consequences for individuals and society at large. Yet the science of lie detection remains not much different than it was 60 years ago, and research shows that FBI, DEA, and CIA officers aren’t much better than random chance at ferreting out lies and liars. The famous polygraph test (i.e. the “lie detector”) has long been known to be unreliable, which is why psychologists have been seeking to augment it with a catalog of other hints of deception, such as posture, gestures, linguistics, and expressions.
The undisputed master of this sort of lie detection is Paul Ekman, professor emeritus of psychology at the University of California Medical School, San Francisco, who started his work with emotional expressions 60 years ago. Beginning in the 1950s and continuing through the 1970s, Ekman began creating a database of every expression the human face is capable of making, ending up with a list of over 3000. In the process, he discovered that not all expressions are of the same order. Some expressions are big, and easy for people to control or conceal. Full, wide-eyed, open-mouthed expressions of terror are relatively easy to mask. But other expressions are small, and move across the face so rapidly that people not only have trouble concealing them, they might not even be consciously aware of them.
While they may only last for a fraction of a second, Ekman has found that these “micro-expressions” are a reliable key to understanding what something is actually feeling. "Sometimes," Ekman says, "you may know how a person is feeling before he or she knows. You may also be able to recognise that there is a chance a person is trying to diminish or conceal her expressions." Micro-expressions may often provide an invaluable insight into the feelings inside another person, because they happen involuntarily, and thus cannot be concealed. A trained professional, however, can spot them, sometimes using a slow-motion camera to assist in making the micro-expressions visible. Such methods may someday contribute to a vastly superior technology of lie-detection—one capable of saving lives.
Has all this research made Ekman himself an accomplished liar? No. "We know from our research that the ability to catch a liar and the ability to lie successfully are totally unrelated," he says. "They rely on very different skills. And although I have been asked to train liars, I don't work that side of the street."
Photo (of a set of 41 micro-expressions in Ekman's Facial Action Coding System) by Buster Benson.