The psychologist Paul Ekman and his colleagues have identified six basic emotions: happiness, sadness, anger, fear, surprise, and disgust. Worldwide, most people can identify the facial expressions that correspond to these emotions.

Some researchers have proposed that the brain uses feedback from facial muscles to recognize emotions that are being experienced. This idea is known as the facial-feedback hypothesis. It follows from this hypothesis that making the facial expression corresponding to a particular emotion can make a person feel that emotion. Studies have shown that this phenomenon does indeed occur.

For example, if people smile and try to look happy, they will feel happiness to some degree.

Some research suggests that the genders differ in how much emotion they express. In North America, women appear to display more emotion than men. Anger is an exception—men tend to express anger more than women, particularly toward strangers.

This gender difference in expressiveness is not absolute. It depends on gender roles, cultural norms, and context: