24 Psychopathy and Aggression STEPHEN PORTER MICHAEL WOODWORTH Psychopathy is a personality disorder char­ Adult Offenders aeterized by a major affective deficit accom­ panied by a disregard for the rights of others A large number of studies have shown that and for societal rules in generaI (e.g., Hare, the presence of psychopathic traits is associ­ 1996). As defined by the well-validated Psy­ ated with a propensity for violent behavior. chopathy Checklist-Revised (PCL-R; Hare, In one of the earliest investigations of the re­ 1991), psychopaths are manipulative, cal­ lationship between psychopathy and vio­ lous, remorseless, impulsive, irresponsible lence, Hare and Jutai (1983) found that individuals (e.g., Hare, 1996, 1998). In this adult psychopathic offenders had been chapter, we begin by outlining the contribu­ charged with violent crimes about twice as tion of psychopathy to the prediction of often as nonpsychopaths. Virtually ali the whether and the degree to which a person psychopaths in their sample had perpetrated will engage in aggressive behavior. Our at­ at least one violent crime compared to about tention then turns to a much newer focus of half of the nonpsychopaths. Within a large research-the characteristics of violent ac­ sample of federal offenders (average age of tions by psychopaths. We review studies in­ 43.5 years), Porter, Birt, and Boer (2001) vestigating the nature of their violence, ex­ found that psychopaths had been convieted amine the possible link between psychopathy of an average of 7.32 violent crimes com­ and sadistic behavior, and consider how this pared to 4.52 violent crimes by nonpsycho­ work informs our understanding of their pathic offenders. This pattern of a relatively criminal motivations. high level of violence by psychopaths is witnessed throughout their criminal careers (e.g., Harpur & Hare, 1994; Porter, Birt, & TUE LlNK BETWEEN PSYCHOPATHY Boer, 2001). Thus, it is dear that psycho­ ANO AGGRESSION paths are a high1y aggressive group simply from examining the sheer number of violent Research has established a strong link be­ crimes they have perpetrated. tween psychopathic traits and aggressive be­ Knowledge of the psychopathy/aggression havior in each of adult offenders, antisocial link greatly aids in the prediction of future chiIdren and àdolescents, and civil psychiat­ violent behavior in adult offenders (e.g., ne patients. Harris, Rice, & Quinsey, 1993; Hemphill, 481 .