Emotion

Common representation of angry emotion experience: "steamed up" with hot glowing eyes, and uncontrolled appearance. Is it the same across people? Interpersonal aggression in the form of instrumental behaviors produced by skeletal muscles is often a concomitant of anger.

A bright idea can bring a pleasant emotion, or pleasant emotions can foster bright ideas.
The component that seems to be the core of common sense approaches to emotion, the one that most people have in mind when talking about human emotions, is the feeling component, i.e., the passion or sensation of emotion. For example, people generally agree that the state of mind during anger is different from that when one is happy. This component is also one of the most contentious in scientific discussions of emotion, raising many questions such as:

• what extent are such feelings, especially the claimed differences in quality, based on real physical differences?
• is the feeling quality of a particular emotion shared among people?
• what is the nature of the differences in quality among emotions?
• what underlies or produces these feelings?
• what importance or function do such feelings have?

Another obvious descriptive component of emotion is the set of behaviors that may be performed and observed in conjunction with an emotion. These behaviors are produced by the striated muscular system and are of two general types:

• gross behaviors of the body effected by the skeletal muscles and the so-called emotion expressions. These categories shade into each other because any behavior can be interpreted as expressing emotion. 
• The gross body behaviors may have no apparent adaptive value, e.g., 
• wringing and rubbing the hands or tapping a foot, or they may be directed towards a goal, e.g., 
• striking something or running away. 
• In the field of animal behavior, discovering the adaptive function and organization of behaviors in situations analogous to human emotion, and speculating on the evolutionary patterns of these behaviors is an established endeavor. 

This emphasis has not typically been given to the study of human emotions by psychologists. The facial and bodily behaviors called "emotion expressions" are indicators of emotion, as opposed to effecting some action or achieving some goal. These expressions can differentiate one emotion from another. The most widely discussed and investigated emotion expressions are the emotion faces (see the examples of emotional expressions).

Adrenalin is a secretion that affects many organs and may contribute to the felt quality of emotion.
A less obvious component of emotion is the set of internal bodily changes caused by the smooth muscles and glands. Chemicals secreted by the body's various glands are activated during emotion and spread to other parts of the body, usually by the blood, to act in diverse ways on the nervous system and other organs. Smooth muscles of the digestive system, circulatory system, and other bodily components can shift from their typical level or type of operation during emotion under the effects of chemical and neural action. This component includes some behaviors that can be observed, such as the constriction or dilation of the iris of the eye, possibly piloerection, and sweating, blanching, and flushing of the skin, and other responses that are relatively hidden, such as heart rate, stomach activity, and saliva production.

Computers often elicit frustration and anger Another less observable component in emotion consists of the ideation, imagery, and thoughts that occur during emotion. These aspects of emotion are also cognitive activities, and can both give rise to an emotional event and be affected by it, e.g., thinking about a lost pet may evoke feelings of sadness, which may in turn evoke memories of a romance now finished. Since thoughts and other cognitions, like feelings, cannot be directly observed and are hard to measure, there is less understanding of how they fit into the emotion picture than other components.

The circumstances that give rise to emotions comprise another component, called the "elicitors" of emotion. These elicitors might be internal or external to the organism, e.g., a frightening pain in one's chest or a frightening dog at one's heels. Some events seem to activate similar emotion in people of all cultures, for example, the death of one's own child typically elicits sadness. Other things, such as what foods are relished or rejected with disgust, vary widely according to acculturation.

Finally, the neural processes that underlie much of the preceding activities can be considered a component of the emotion process, especially how the neurons and their emotional concomitants are organized centrally in the brain. Many contemporary research studies, and thus a lot of the research money, is focussed on anatomical and functional aspects of brain activity in regard to emotion