Fractions of a second can ruin a well-developed poker face

Psychologists will tell you that the question they are most frequently asked is, "What am I thinking right now?" Dr. Paul Ekman, psychology professor emeritus at University of California, San Francisco, can tell what you're feeling, but not what you're thinking.

We all automatically scan each other's faces for signs of emotion. We can be right or wrong about the emotions that we ascribe to these facial expressions. What's more, we can be right about the emotion but wrong about the reason for it. For example, someone under interrogation could display anxiety because he told a lie, or because he is worried that the interviewer mistakenly considers him a liar. Dr. Ekman can recognize microexpressions, fleeting involuntary changes in facial expression that move across even the best liar's face.¹ So Dr. Ekman can catch eruptions of true emotion that make it to the surface.

TV producer Brian Grazer, responsible for 24 and Frost/Nixon, based a television show on Dr. Ekman's work. The show is called Lie to Me, and is part of Rupert Murdoch's US Fox network. Dr. Ekman is deeply involved in the project. He talks through plot ideas, checks five successive drafts of each script for accuracy, and even sends the actors videos of himself making funny faces.

The research started off far from Hollywood in an effort to figure out whether facial expressions are hard-wired or culturally constructed. Interestingly, Darwin had a whole book on the subject, called The Expression of the Emotions in Man and Animals. This book was published in 1872 and largely ignored. Dr. Ekman wanted to revisit the subject. He wondered whether children in one culture learned by watching facial expressions on others. He found that Brazilians could pick out emotions on North American faces, evidence that argued against the cultural construction hypothesis. The same was true in Chile, Argentina, and Japan. So Dr. Ekman explored the issue among members of a non-modern society. He went to the island of New Guinea and his research there convinced him that basic emotions are associated with universal facial expressions.

This research resulted in a facial action coding system (FACS), first publicized in 1978. Not to be confused with the FACS system used for flow cytometry, Dr. Ekman's system makes it possible to describe and classify any facial expression based on a combination of 43 facial muscle movements. Interestingly, coordinated tightening of certain facial muscles not only affects blood pressure and heart rate, but can also trigger the corresponding emotion. So it really is true that it's harder to be said when someone makes you smile. Feedback between the facial muscles and the brain's emotion centers thus plays an important role.

By the early 1980s, FACS was applied to real-life situations. The secret to its success was the microexpression mentioned earlier, which lasts no more than 1/15 of a second. These microexpressions show that the control we exert over our own facial features is limited. People who use FACS and focus on microexpressions can learn to read signals that previously would only have been seen in slow-motion videotape. It's a difficult process for 99% of the population, but intuitive for a select few.² Given a lot of training, anyone can develop the skill. You can imagine the implications for law enforcement, anti-terrorism experts, etc.

Nonetheless, lies can be of value. From an evolutionary perspective, one wouldn't expect humans to be perfect lie detectors. White lies can gloss over unimportant inequities. If the earliest human societies practiced a zero tolerance policy, smooth talkers would have been kicked out, without much real benefit for the group. But where does our biology draw the line? When a lie endangers the well-being of another, today's society can send the perpetrator to jail for fraud or perjury. Our highly polished attempt to send them outside the cave.

¹Schubert, Siri. A look tells all. Scientific American. October 2006.

²Henly, Jon. The truth about lying. The Guardian. 12 May 2009.