Main idea of the theory: Emotions are generated due to the abnormal and sudden changes in the body.

James-Lange Theory of emotion suggests that emotions come from bodily responses. As we encounter a stimuli, an arousal is experienced and our body starts reacting. When this happens, our brain interprets these reactions from what it already knows, and this gives rise to emotions accordingly. For example: A boy is sleeping in the night. He hears a sound, and thinks this might be a ghost. His heartbeat grows faster, and he starts trembling. His brain reads these reactions and interprets them as those experienced in a scary situation, thus resulting in the emotion of fear. There are six primary emotions. Everybody has felt these emotions except for those who have emotional disorders. According to James-Lange theory, our brain is triggered by what it perceives from the actions and reactions of our body, due to a stimuli. A stimuli can be any situation or a thing or a person that makes us react to it. For example: If you laugh while watching a show going on in the television, that show is the stimulus. Your laughter is the arousal (body reaction), and when you are laughing your brain interprets this reaction as being happy. So, happy is the emotion caused due to the arousal, laughter. Experimentation was a difficult thing to do at that time since they did not have enough knowledge and information about how exactly a physical reaction occurs in a body and the chemicals involved in it. To prove this theory, James suggested an experiment on an emotionless person. He stated that if his subject was introduced to a stimulus, his body would still react without producing any emotion. He also stated that a stimulus would make anyone react, unless the person is completely anesthetic. This proved that emotions don't occur without the reaction a body gives, and it's not the emotions that cause the physiological reactions. According to this theory, the autonomic nervous system (ANS) reacts to a stimulus as it is encountered, and results in increased heart rate or heavy perspiration, which is then interpreted by the brain, resulting in emotions. One example James gave was that of a bear. It is common sense that if a person sees a bear, he will be scared and try to run from there. As soon as he sees it, his heart rate will increase, adrenaline will rush and his brain will interpret this physiological change as a frightening situation and result in the emotion of fear. Walter Cannon, an American physiologist came up with a theory in the 1920s that challenged James-Lange theory. With thorough experimentation, Cannon deduced seven points which proved their theory wrong. It stated that emotions and physiological responses are simultaneous events that occur in a person. He conducted tests on cats, severing their ANS' sympathetic branch, which proved that cats still felt emotion without the nerves that gave physical responses. As we experience a stimulus, sensory signals are sent to the thalamus, a part of brain that is involved in sensory perceptions. Thalamus then sends signals to amygdala, which is the integrative center for emotions, and to the brain cortex, that is largely responsible for higher brain functions, including sensation, voluntary muscle movement, thought, etc. Concurrently the ANS also sends signals to body muscles, causing the physical responses. This proves that both emotions and physiological response is a simultaneous process. However, this theory was more relevant with proofs and tests conducted by Cannon. James-Lange theory was the reason other theorists started refuting on the theory of emotions and came up with newer and clearer approaches. This theory hence, plays an important role in the study and research of the process of emotions.