Vagal tone: An autonomic mediator of affect

The autonomic nervous system and theories of emotion Overview Descriptions of emotion frequently include both a physiological and a facial expressive component. The physiological component has been described as changes in the peripheral autonomic nervous system often characterized by increased sweating, throbbing of the heart, pupillary dilation, facial flush, and gastric motility. These physiological responses have been hypothesized as either a necessary mediating mechanism or a peripheral correlate of the emotional experience (Cannon, 1927; James, 1884). Moreover, there is renewed speculation that some physiological signatures are associated with specific emotional states (e.g., Ekman, Levenson, & Friesen, 1983). In contrast with the research that has eloquently described detailed facial patterns and the social contexts associated with specific emotions, the role of physiology in the development of expressivity and the regulation of affect has not been adequately investigated. Although in the temperament literature a physiological substrate is commonly assumed to be related to the regulation of affect (e.g., Bates, Freeland, & Lounsbury, 1979; Rothbart & Derryberry, 1981), physiological measures are seldom quantified. Moreover, physiological constructs rarely motivate this area of research or provide insight into individual variations in the regulation and expression of affect.