The Cannon-Bard theory is a psychological explanation of emotions. Its main concept is that bodily arousal and emotional experience occur simultaneously. In the cannon-bard theory, the thalamic area of the brain is the key player.
The Cannon-Bard theory was developed in 1927 by psychologist Walter Cannon and his doctoral student Philip Bard. The theory was created as opposed to the James-Lange theory of emotion that was dominant at that time. James-Lange theory suggests that when a person encounters some stimulus, it causes a bodily reaction (arousal) at first, and after that, an individual experiences an emotion.
It means that if a person sees a snake, for example, the sight of it causes the heart to beat faster, and the increased heartbeat tells the person that he or she is scared. According to the Cannon-Bard theory of emotion, arousal and emotional experience occur at the same time and do not depend on each other.
The Cannon-Bard theory is also referred to as the Thalamic theory because it suggests that emotional reaction comes from the stimulation of the thalamus, a small structure located in the brain. When a person is exposed to a stimulus, the thalamus sends a signal to the amygdala, a small region of the brain responsible for memory and emotional responses. At the same time, the thalamus sends a signal to the nervous system and muscles, which causes a physical reaction. An example of the Cannon-Bard theory is a situation when a person watches a scary movie.
At the moment when a monster suddenly appears on the screen, the image of this creature and its sounds are transmitted to the thalamus that immediately sends signals to the amygdala and the nervous system. As a result, a person experiences an emotion, fear, and responds to the stimulus physically, for example, sweats or feels a rapid heartbeat.
The Cannon-Bard theory caused some criticism despite the fact that it explained the nature of emotions more precisely than the James-Lange theory. According to Cannon and Bard, bodily reactions have no influence on emotional experiences. However, further studies show that the scientists were wrong in this suggestion. For example, it has been found that if a person deliberately changes his or her facial expression, it makes him or her feel emotions corresponding to that countenance. Furthermore, the theory is criticized for paying too much attention to the thalamus and disregarding other brain structures.
The Cannon-Bard theory is opposed by the Schachter-Singer theory, also known as the two-factor theory. According to this theory, bodily arousal is identic in all cases, and it happens before a person experiences an emotion. However, the kind of emotional response is determined by the cognitive appraisal of a stimulus. For example, if a person sees a barking dog, it makes his heart beat faster. At the same time, a person thinks that the dog can chase and bite him or her. This mental assessment of the barking dog, alongside the rapid heartbeat, makes a person realize that he or she is afraid.
This theory explains why people sometimes cannot tell for sure what emotion they experience. It happens because they fail to label a stimulus correctly. Although each of the three theories argues different things, each of them gained both evidential support and criticism. The major argument in favor of the Cannon-Bard theory is that the signal about a stimulus spreads so fast that it seems that arousal and emotion occur simultaneously.