According to the physiological animal model proposed by Gorenstein and Newman (1980; see also Newman, Gorenstein, & Kelsey, 1983), psychopaths and extraverts may be characterized by a common psychological diathesis related to behavioral inhibition (see also Fowles, 1980; Gray, 1982). One aspect of this diathesis involves deficient passive avoidance learning, which has been central to explanations of "unsocialized" (e.g., Trasler, 1978) and antisocial behavior (e.g., Hare, 1970). Results from three experiments supported our prediction that psychopaths and extraverts would exhibit deficient passive avoidance relative to nonpsychopaths and introverts, respectively. In addition, the passive avoidance deficit was particularly evident in tasks that required subjects to inhibit a rewarded response in order to avoid punishment. The latter finding may be important for explaining the inconsistent results regarding passive avoidance learning in psychopaths (e.g., Chesno & Kilmann, 1975; Schmauk, 1970). Discussion of the results focuses on the importance of reward in mediating the passive avoidance deficit of "disinhibited" individuals and on the existence of an indirect relationship between psychopathy and extraversion: one that is consistent with the observed experimental parallels as well as with the more ambiguous evidence regarding a direct correlation between measures of the two syndromes.