Narrator: This is Science Today. Around the world, hundreds of people in law enforcement, medicine and psychology have learned a technique to decipher facial expressions. It's called the Facial Action Coding System and it was developed over 20 years ago by Dr. Paul Ekman, a psychology professor at the University of California, San Francisco.
Ekman: Our research system allows us to measure anything that the face does. And one can conceivably make more than ten thousand expressions. Each one a different appearance, but you never see that. But it's not uncommon in a 30-minute conversation to see two or three hundred different expressions that are occurring, but the three most common are the non-enjoyment smile, the enjoyment smile and the raising of eyebrows.
Narrator: There are seven clear facial signals of human emotion. They are: anger, sadness, fear, surprise, disgust, contempt and happiness. For Science Today, I'm Larissa Branin.