facial expression Can we trust our interpretation of a foreigner's facial expressions; do we need an expression translator? Are expressions, like gestures and words, socially learned and therefore culture-specific in their meaning? Or are our expressions the product of our evolution and therefore universal? Why do the eyebrows go up in surprise rather than down? Do other animals have facial expressions, and if so do they have the same meaning as they do in humans? Can we use our expressions to lie about how we are feeling, or are they more reliable than words?

The great evolutionary theorist Charles Darwin wrote a book about facial expression. The Expression of the Emotions in Man and Animals, in which he considered these questions (except the one about lying). Remarkably, many of his observations, first published in 1872, have recently been proven to be largely correct. As Darwin suggested, the facial expressions of a number of emotions are universal, not culture-specific. The muscles that contract to produce the facial expressions of anger, fear, sadness, disgust, and enjoyment are the same the world over, regardless of sex or culture. Three kinds of research have established this. When people from various cultures have been asked to identify the emotions represented by photographs of different expressions, they have, by and large, given the same answers. In one set of studies the people studied were from an isolated, Stone Age culture in New Guinea, who, at the time, could not have learned how to make or interpret expressions from outsiders or the media. A second type of research asked people to use their faces to imitate different emotions, and found members of different cultures produced the same expressions. The figure shows people from the isolated New Guinea culture posing three of the emotions. The last type of research measured spontaneous expressions when people in different cultures were subject to the same emotional conditions, and found that the same expressions were shown under the same circumstances.

There may also be universal expressions for surprise, contempt, and embarrassment as it is for anger, fear, sadness, disgust and enjoyment, but the evidence is not as complete. Love and hate — which probably don't have unique facial expressions — involve strong feelings, but those feelings endure much longer than the emotions, which can last only seconds or at most minutes. Love and hate may be better thought of as affective attitudes rather than momentary emotions. There may be facial expressions for other emotions such as shame or awe, but these have yet to be identified.

Not everything about facial expressions of emotion is universal. All people learn, in the course of growing up, to manage their facial expressions. Polite and proper behaviour requires that we employ what have been termed display rules that dictate who can show which emotions to whom, and when. For example, in many societies, people who lose in a public contest try to inhibit any sign of their disappointment. Although we know what we should do, that does not always mean that a display rule is actually followed. There are cultural differences in display rules. For example, in one experiment, when a person in authority was present, Japanese masked with a polite smile the sign of any negative emotions more than did Americans. When there was no one present, then American and Japanese subjects showed the same emotional expression when watching different emotional scenes. Misunderstandings in cross-cultural communication occur when people do not realize that it is a difference of display rule that makes for a different expression, not the underlying emotion.

Darwin also tried to explain why we make the particular expressions that we do for particular emotions. Why do the eyebrows go up rather than down in surprise? Building on Darwin's ideas, contemporary theorists believe that these expressions originated in movements that were of functional value — raising the brows might let in more light, raising the upper lip exposes the teeth, and so forth. Over the course of our evolutionary history these movements have been ritualized, to communicate intentions to others. The most difficult expression to explain is the smile.

Darwin claimed that emotions and their expressions are not unique to humans but shared with other animals. Nearly all of our facial muscles can be found in other primates. Chimpanzees, for example, show some expressions that bear a resemblance to human expressions. But do they actually feel the same emotions? Without the capacity for words they probably cannot think about or make plans about their emotions as easily as we do. But they do show similar expressions to ours when they are playing, threatened by harm, about to attack, or when their young offspring are removed. When we look at animals with less developed brains, we find that vocalizations play a more important role than facial expressions. In humans, both the face and the voice signal emotions.

Facial expressions of emotion are involuntary and are produced almost immediately when an emotion occurs. Yet we can, to a large extent, interrupt or suppress expressions if we concentrate on doing so. We can also deliberately put on expressions of certain emotions when we do not feel them. This is hard to do for fear and sadness, because most people do not have voluntary control over the specific facial muscles that are deployed in those expressions. False expressions of enjoyment, anger, disgust, and surprise are easy to make, although careful measurement of the speed, symmetry, and specific muscular activity suggests that it is possible to distinguish the spontaneous from the false expressions of even these emotions.

Different areas of the brain are involved in the recognition of emotion (what does that person feel?) and the recognition of identity (who is that person?). Patients with damage (from stroke or accident) to one brain area may not know who other people are, but they do know how they feel, while those with damage to another brain area know who people are but not how they feel. Recent research has found that the perception of different facial expressions of emotion activates different brain areas, suggesting that not only are we highly sensitive to facial expression, but very specialized mechanisms have evolved to process this information.

Paul Ekman

See also emotion; face.