Pain is not a sense, like touch, sight, or hearing. Pain is an emotion (Wells & Nown, 1998). Hence, emotion is a fundamental part of the pain experience and not a reaction to the sensory appreciation of pain. Given its complexity, it has been harder to define emotion. For most of us, when we think of emotion, we associate it with the limbic system and generally recognized emotion to be a sensation-like feeling that compels us to act in certain ways. Other definition of emotions has defined it as "the nervous process that determines what kind of stimuli coming from the inner and outer environments are desirable for the organism and what are not". Yet another definition of emotion states that it is "a transitory social role (a social constituted syndrome) that includes an individual's appraisal of a situation and that is interpreted as a passion rather than as an action" (Bromm & Desmedt, 1995). The difference in these definitions and many other definition of emotion not listed here, reflects the divergent theoretical frameworks within which emotion researchers work, and their investigation of different subjective, behavioral, and social events.
There are also many different theories of emotion (Bromm & Desmedt, 1995). For example, one theory proposed by Izard and Blumberg in 1985, states that "the emotion system is viewed as the principle motivational system for human beings. The emotion s are seen as adaptive and motivating organizers of experience and behavior" (Bromm & Desmedt, 1995). From this point of view, pain-induced emotion represents disruption and a redirection of activity. This notion of emotion is also shared by another researcher by the name of Frijda, who states that emotions "can be defined in terms of some form of action tendency or some form of activation or lack thereof" (Bromm & Desmdt, 1995).
Despite these differences in defining what emotion is, there is sufficient agreement among mainstream emotion researchers on the following six points (Bromm & Desmedt, 1995): a) Emotional responses to stimuli and emotional expression subserve biological adaptation and emotional phenomena evolved to foster survival of the individual and the species. b) Emotions impute positive or negative hedonic qualities to a stimulus in accordance with the biologic importance and meaning of that stimulus. c) The central neuroanatomy for emotion corresponds to the limbic brain. d) Emotion activates - they produce impulses to act or to express one self. e) Emotions communicate, and the negative emotional expression of one individual will tend to produce negative emotion in another. f) Human cognition and emotions function interdependently. These points of agreement help to clarify what science currently mean by emotion, but as far as having a conclusive definition for emotion goes, there is not a universally accepted definition.