paths could engage in homicides that, although goal-directed, are highly impulsive and involve little planning (having elements of both instrumentality and reactivity). Thus, in addition to homicides that appear to be exclusively instrumental or reactive, some pri- marily instrumental homicides may contain a reactive component, and some primarily reactive homicides may contain an instrumen- tal component. Conceptually, this complex or diverse violent be- havior seems plausible because the current construct of psychop- athy encompasses both affective/interpersonal traits, known as Factor 1 characteristics on the PCL–R (e.g., glibness and superfi- cial charm, pathological lying, lack of remorse, and shallow affect) as well as Factor 2 characteristics associated with a chronically antisocial and unstable lifestyle (e.g., a need for stimulation, im- pulsivity, lack of realistic goals, and promiscuity). There is some evidence that instrumental aggression is related to the Factor 1 features of psychopathy, whereas reactive aggression is more associated with the Factor 2 characteristics (e.g., Patrick & Zem- polich, 1998). The present study addressed these issues and was the first to specifically examine the relationship between psychop- athy and homicidal violence.
The sample was composed of incarcerated homicide offenders (in the year 2000) from two Canadian federal institutions, one in British Columbia on the west coast and one in Nova Scotia on the east coast. The inclusion of offenders from two prisons allowed a large sample size and could increase the generalizability of the findings. Mountain Institution is a medium-security prison located in British Columbia that houses approxi- mately 400 inmates at any given time. A review of file information indicated that a total of 92 offenders had committed at least one homicide, and extensive efforts were made to obtain adequate information on these homicides to include them in our sample. There was detailed file informa- tion on the homicide in 74 cases, which were included. The second prison (Springhill Institution) is a medium-security prison located in Nova Scotia also housing approximately 400 inmates. At the time of data collection, there were 54 homicide offenders in this institution. Of these, detailed file information regarding the homicide was available in 51 cases. Thus, in total, there was detailed information on 125 homicide offenders.
Materials PCL–R (Hare, 1991). The PCL–R has been widely adopted in the
assessment of psychopathy in forensic populations. Psychopathy, as mea- sured by the PCL–R, is characterized by 20 criteria, scored as 0, 1, or 2, allowing a maximum score of 40. As recommended in the manual, a score of !30 was the cut-off used for classifying psychopathy (Hare, 1991). The PCL–R score is highly reliable over time and has demonstrated validity according to a number of indices of validity (e.g., Fulero, 1995; Stone, 1995). Although there has been some debate over whether psychopathy represents a discrete or a continuous variable (e.g., Harris, Rice, & Quin- sey, 1994), recent research suggests that psychopathy may represent a distinct clinical entity or taxon (see Hart & Hare, 1997). Nonetheless, we used both a dichotomous and a continuous score approach to examine psychopathy and homicide.
In the Canadian correctional system, risk assessments for the purposes of conditional release and treatment programs normally include an evaluation of psychopathy by a psychologist who has been well trained in the administration of the PCL–R. PCL–R assessments are typically conducted as part of the intake assessment and for conditional release decisions and are based on a structured interview as well as a thorough review of all
collateral and historical information. A file search yielded all available PCL–R scores and corresponding Factor 1 and Factor 2 scores as reported in the official risk assessments. (It is now a requirement of the Canadian correctional system that a risk assessment [including a PCL–R] be con- ducted on all violent offenders.) However, due to the recentness of this policy, 29 offenders from the Springhill sample still required a PCL–R rating. Although PCL–R assessments are often based on a review of file information and an interview with the offender, research (e.g., Grann, Langstroem, Tengstroem, & Stalenheim, 1998; Wong, 1988) has consis- tently shown that assessments based solely on the offender’s file informa- tion are highly similar to ratings including an interview (see Hare, 1991) and are appropriate in the absence of an interview (provided that there is sufficient file information to code the PCL–R; files on Canadian federal offenders are generally extensive, detailed, and multifaceted). For the current study, a graduate student in psychology and a senior undergraduate student who had been trained in administering the PCL–R reviewed all available official file information and scored the 29 other PCL–Rs. These raters were kept blind to the purpose and hypotheses of the study to prevent any bias in their scoring of the PCL–R. File documentation concerning the homicide. The crime information