The Three Arousal Model: Implications of Gray's Two‐Factor Learning Theory for Heart Rate, Electrodermal Activity, and Psychopathy

ABSTRACT Gray's two‐factor learning theory postulates a behavioral activation system (BAS), a behavioral inhibition system (BIS), and a nonspecific arousal system receiving excitatory inputs from both the BAS and the BIS. The BAS initiates behavior in response to conditioned stimuli for reward (approach) or for relieving nonpunishment (active avoidance). The BIS, which is viewed as an anxiety system, inhibits behavior in response to cues for punishment (passive avoidance) or frustrative nonreward (extinction), and its activity is decreased by the anti‐anxiety drugs (alcohol, barbiturates, minor tranquilizers). Thus, the BIS is an arousal system which inhibits rather than energizes behavior. A review of the literature suggests that heart rate (HR) is strongly associated with activity of the BAS. This interpretation subsumes the previous findings of cardiac‐somatic coupling, incentive effects on HR, and increased HR in connection with active coping in the face of threat. Electrodermal activity (EDA), on the other hand, increases when there is an activation of the BIS. A consideration of these differing effects on HR and EDA permits a specification of conditions in which these two measures will or will not show directional fractionation. With this theoretical model it is possible to relate the clinical features of psychopathy to the psychophysiological data with the single assumption that primary psychopaths have a deficient BIS. As a result, they show normal approach, active avoidance, and HR, but they suffer from poor passive avoidance and extinction with reduced EDA in response to threatening stimuli.