Darwin believed that body movements and facial expressions (body language, or nonverbal communication) are used by members of a species to communicate meaning. He suggested that although emotional expressions are initially learned behavior, they eventually evolve to become innate in a species because they have survival value. Recognition by one animal that a second animal is afraid rather than angry, for example, allows appropriate survival actions to be undertaken.
The James‐Lange theory. Two theorists, William James in 1884 and Carl Lange in 1885, independently proposed that emotions do not immediately follow the perception of an event but rather occur after the body has responded to the event. Their ideas were combined into the James‐Lange theory of emotion. According to the theory, the perception of an environmental stimulus (such as a growling dog) causes bodily changes (such as rapid heart beat and fast breathing). The brain perceives those changes in behavior and identifies them as the emotion. The progression is
The Cannon‐Bard theory. Walter Cannon criticized the James‐Lange theory for several reasons. He argued that emotion occurs even if the bodily changes which transmit feedback to the brain are eliminated. He severed neural connections to the cortex of cats (creating “decorticate cats”). The decorticate cats, when provoked, exhibited the emotional behavior normally associated with rage and aggression, as demonstrated by erect hair, growling, and the baring of teeth. (Canon called the behavior sham rage because according to the James‐Lange theory emotional behavior could not occur without connections to the brain.) In addition, Cannon argued that visceral responses occur too slowly to be recognized by the brain before emotional responses to a stimuli occur.
Philip Bard agreed with Cannon and expanded on his work in what is now known as the Cannon‐Bard theory (also called the emergency theory), which argues that the thalamus, a lower brain stem structure (part of the limbic system) is necessary for emotional responses. The thalamus sends messages to the cortex for interpretation of the emotion and simultaneously to the sympathetic nervous system for appropriate physical responses. According to the Cannon‐Bard theory, then, the identification (experience) of an emotion occurs at the same time as the activation of bodily responses and not because of them (as the James‐Lange theory proposed). The progression is
The Schachter‐Singer theory. Stanley Schachter and Jerome Singer proposed that experiencing an emotion requires both emotional arousal and cognitive activity (perception, reasoning, memory) to understand the reason for the arousal (that is, to appraise the stimuli) so that the emotion can then be appropriately identified. (The process of labeling the stimuli producing an emotion is called attribution.) Schachter and Singer concluded that although individuals usually are aware of the reason for their aroused emotional state, if the reason is not apparent, they search their environment for clues to help them interpret the emotion. Although this theory has generated a great deal of research, experimental data only partially support it.
Arousal theory. Many researchers propose that behavior changes as a function of arousal. The curve (called an inverted U function) shown in Figure illustrates that performance increases as arousal increases up to a point but then decreases if arousal is increased beyond that point. This arousal‐performance phenomenon is known as the Yerkes‐Dodson law. It is well known that while a certain amount of anxiety can enhance performance (for example, by promoting thorough preparation), too much can impair it (as could, for example, severe stage fright). Research evidence has not totally supported the inverted U relationship for all types of tasks, particularly those that are complex.
The Inverted U Function