Emotion is usually considered to be a feeling about or reaction to certain important events or thoughts. An emotion can be either pleasant or unpleasant. An individual also may have a mixture of both pleasant and unpleasant emotions. People enjoy feeling such pleasant emotions as love, happiness, and contentment. They often try to avoid feeling unpleasant emotions, such as loneliness, worry, and grief. However, people are sometimes not fully aware of their own emotions. Although most people believe they know what an emotion is, psychologists have not yet agreed on a definition that applies to both human beings and other animals.
Individuals communicate most of their emotions by means of words, a variety of other sounds, facial expressions, and gestures. For example, anger causes many people to frown, make a fist, and yell. People learn ways of showing some of their emotions from members of their society, though heredity may determine some emotional behaviour. Research has shown that different isolated peoples show emotions by means of similar facial expressions. Even children who are born blind have facial expressions like those of sighted children.
Early theories about emotions.
Charles Darwin, the British scientist who developed the theory of natural selection, also studied emotion. In his book The Expression of the Emotions in Man and Animals (1872), Darwin said that emotional behaviour originally served both as an aid to survival and as a method of communicating intentions. For example, angry people show their teeth because they have inherited behaviour patterns that their prehistoric ancestors needed for fighting. Bared teeth also signal an intention to attack.
During the 1880's, the American psychologist William James and the Danish physiologist Carl G. Lange independently reached another conclusion about emotions. According to their theory, the James-Lange theory of emotions, people feel emotions only if aware of their own internal physical reactions to events, such as increased heart rate or blood pressure. Some psychologists still believe in the James-Lange theory, but there is little evidence to support it.
John B. Watson, an American psychologist who helped found the school of psychology called behaviourism, believed emotions were psychophysical (mental and bodily) reactions to specific events. He observed that babies stimulated by certain events, such as falling, having their arms held tightly, or being stroked, showed three basic emotions. He labelled these emotions fear, anger, and love. Watson's view that there are only three basic emotions has been challenged frequently since he proposed it in 1919.
In 1927, the American physiologist Walter B. Cannon and his associate Philip Bard proposed the Cannon-Bard theory of emotions. Cannon and Bard thought emotions arose only when the hypothalamus, a part of the brain, was stimulated. They believed the hypothalamus was the "seat" of emotions. Several researchers have since shown that stimulation of different parts of the brain, especially the limbic system, triggers emotions.
Modern theories about emotion. In 1962, the American psychologist Stanley Schachter proposed a two-factor theory of emotion, based on an experiment he conducted with Jerome E. Singer. The two factors that determine different emotions, he claimed, are physical changes in a person's body plus the reason the individual gives for those changes. This theory states that emotions result from people's interpretations of their situations after they have been physiologically stimulated. Later research shows that the physiological stimulation may be less important than originally thought.
The most widely accepted view is that emotions occur as a complex sequence of events. The sequence begins when a person encounters an important event or thought. The person then interprets the meaning of the encounter, and the interpretation determines the feeling that is likely to follow. For example, someone who encounters an escaped lion would probably interpret the event as dangerous. The sense of danger would cause the individual to feel fear. Each feeling is followed by a series of physical changes and impulses to action, which are responses to the event that started the sequence. Thus, the person who met the lion would probably run away, increasing the person's chances of survival.
Several American psychologists have independently developed the theory that there are eight basic emotions. These emotions--which can exist at various levels of intensity--are anger, fear, joy, sadness, acceptance, disgust, surprise, and interest or curiosity. They combine to form all other emotions.
