Emotion is a mental state associated with the nervous system brought on by chemical changes associated with thoughts, feelings, behavioral responses, and a degree of pleasure or displeasure. There is currently no scientific consensus on a definition. Emotion is often intertwined with mood, temperament, personality, disposition, and motivation.
Emotions are associated with psychology, neuroscience, endocrinology, medicine, history, sociology of emotions, and computer science. Current research areas in the concept of emotion include the development of materials that stimulate and elicit emotion. In addition, PET scans and fMRI scans help study the affective picture processes in the brain.
"Emotions can be defined as a positive or negative experience associated with a particular pattern of physiological activity." Emotions produce different physiological, behavioral, and cognitive changes. The original role of emotions was to motivate adaptive behaviors that in the past would have contributed to the passing on of genes through survival, reproduction, and kin selection.
Cognition is an important aspect of emotion. Those acting primarily on the emotions they are feeling may seem as if they are not thinking, but mental processes are still essential, particularly in the interpretation of events. For example, the realization of our belief that we are in a dangerous situation and the subsequent arousal of our body's nervous system (rapid heartbeat and breathing, sweating, muscle tension) is integral to the experience of our feeling afraid.
Emotions are complex. According to some theories, they are states of feeling that result in physical and psychological changes that influence our behavior. The physiology of emotion is closely linked to arousal of the nervous system with various states and strengths of arousal relating, apparently, to particular emotions. Emotion is also linked to behavioral tendency. Extroverted people are more likely to be social and express their emotions, while introverted people are more likely to be more socially withdrawn and conceal their emotions. Emotion is often the driving force behind motivation, positive or negative.