The term microexpression
denotes a brief facial expression
that lasts less than a quarter of a second. They often occur involuntarily, and can reveal emotions
not deliberately expressed.
In the 1960s, William Condon
pioneered the study of interactions at the fraction-of-a-second level. In his famous research project, he scrutinized a four-and-a-half-second film segment frame by frame, where each frame represented 1/45th second. After studying this film segment for a year and a half, he discerned interactional “micromovements”, such as the wife moving her shoulder exactly as the husband's hands came up, which combined yielded “microrhythms”.
American psychologist John Gottman began video-recording living relationships to study how couples interact. By studying these micro-movements, Gottman was able to predict which relationships would hold and which would dissolve.
Most people do not seem to perceive microexpressions in themselves or others. In the Diogenes Project, for example, researcher Paul Ekman found that these tiny movements often can expose lying, and that a very, very small percentage of those he studied had a preternatural knack for detecting them. He now claims that anyone can be trained to see such microexpressions relatively easily.