An intuitive view of emotions is that we perceive some stimulus or situation (e.g., a lion), we then experience a pertinent emotion (e.g. fear), and the emotion then engenders various bodily responses (e.g. trembling, racing heart, etc.). Cornelius refers to this as a "common-sense" view of emotions.
The American psychologist, William James (1842-1910), and the Danish physiologist Carl Lange [pronounced 'Long'] (1834-1900) independently offered a counter-intuitive view that emotions arise from perceiving changes to our bodily states. For example, we experience the emotion of "fear" by perceiving our bodily state. That is, the racing heart, trembling arms and legs, the profuse sweating are not symptoms of fear; rather they are the psychological causes of fear.
Lange emphasized the importance of the viscera (stomach, intestines, heart, etc.). James included other bodily responses (skin, peripheral muscles, etc.) in addition to the viscera.
Of course the body (e.g. viscera) do not directly sense external stimuli. All sensory nerves pass through "ancient" structures in the brain that are associated with (fast) reflexes and autonomic functions. A less naive view of the James-Lange model would recognize the role of the phylogenetically ancient parts of the brain.
The "slower" brain (neocortex) is associated with conscious thought and awareness. A neo-Jamesian perspective regards the neocortex as the "interpreter/perceiver" of changes of bodily states.
Experiments by Zajonc support a neo-Jamesian interpretation. Zajonc showed that manipulating facial musculature could evoke changes of mood consistent with the corresponding facial expression -- without the subject's awareness of the facial expression.
Magda Arnold argued that emotions depend on cognitive interpretations and appraisals of objects and situations. The emotions we experience depend on how we understand the repercussions for ourselves, and how we think about the meaning of events.
Lazarus and Alfert (1964), for example showed an anthropological film of a crude operation to a number of subjects. In one condition, subjects were told that the operation was not at all painful ("denial" condition), whereas in other conditions, the painfulness of the operation was exaggerated ("trauma" condition). Skin conductance responses of the subjects showed that the magnitude of the emotional response was influenced by the cognitive interpretation of events offered to the viewer.
George Mandler regards emotions as, in effect, signals to consciousness that alert an individual to re-evaluate or assess the meaning and significance of current events. Changes of activity in the sympathetic nervous system act like computer "interrupts" that commandeer cognitive processes.
A problem with the cognitive account arises from the work of Posner & Snyder (1975), who found that reaction times to make affective judgments are faster than reactions times for recognizing stimuli. (In effect, one has a positive emotional response to a photograph of a loved one, even before one is able to recognize who the person is.)
Our integrated view incorporates Mandler's basic model, recognizing that physiological states signal consciousness to evaluate a situation. We have added a feedback connection where the slow brain influences the operation of the fast brain. Phylogenetically, the slow brain structures tend to have an inhibitory role -- as when anticipating the slamming of a door causes the ensuing startle response to be attenuated in magnitude.
Our integrated model also includes aspects of the neo-Jamesian research, such as Zajonc's observations concerning how manipulations of musculature can evoke changes of mood.