cantly to the prediction model, chR2 ” .31, F(1, 45) ” 33.38, p # .001. Finally, when the impulsivity dimension was included in the model, it also significantly added to the prediction model, chR2 ” .14, F(1, 44) ” 21.56, p # .001. However, with all three variables entered concurrently into the model, only the impulsivity dimen- sion uniquely predicted instrumental/reactive ratings, $ ” $.65, t(44) ” $4.64, p # .001, whereas affect, $ ” $.10, t(44) ” $.93, p ” .36, and gain ratings, $ ” .181, t(44) ” 1.52, p ” .14, did not predict scores independently.

It also was important to examine how the three dimensions of the homicide offense were related to the offender’s overall PCL–R score. Results indicated that although the presence of external gain was significantly positively related total PCL–R score, r(112) ” .28, p # .01, the presence of impulsivity was significantly nega- tively related to total PCL–R score, r(112) ” $.26, p # .01.

Affective arousal was negatively related to total PCL–R score, but the correlation was nonsignificant, r(52) ” $.17, p ” .23.

To examine the relative contributions of Factor 1 (F1; interper- sonal/affective traits) and Factor 2 (F2; antisocial behavior) in predicting the degree of instrumentality within the homicides, a regression model consisting of F1 and F2 scores (entered simul- taneously into the model) was conducted. The regression equation was significant, adjR2 ” .20, F(2, 112) ” 15.65, p # .001. Although the partial correlation for F1 scores was significant, r(115) ” .37, p # .001, the partial correlation for F2 scores was not, r(115) ” .09, p ! .05, suggesting that F1 but not F2 scores played a role in predicting the level of instrumentality in the crime. These results were confirmed by a calculation of the zero-order correlations between PCL–R total score, Factor 1, Factor 2, and the type of homicide (see Table 1).

Figure 1. Primary nature of homicides as a function of psychopathy.

Table 1 Zero-Order and Partial Correlations Between Factor 1, Factor 2, PCL–R Total, and Homicide Type

Type of correlation Factor 1 Factor 2 PCL–R total Homicide type

Zero-order correlation Factor 1 — .53* .85* .46* Factor 2 — .87* .31* PCL–R total — .45* Homicide type —

Partial correlation, with Factor 1 removed Factor 2 — .09 PCL–R total — .13

Partial correlation, with Factor 2 removed Factor 1 — .37* PCL–R total — .39*

Note. PCL–R ” Psychopathy Checklist—Revised. * p # .001.

441PSYCHOPATHY AND HOMICIDE

Sylviane Houssais

Psychopathy and victim gender. In 41.6% of the homicides, the victim was male and in 54.4% cases the victim was female. The relationship between psychopathy and victim gender was significant, #2(2, N ” 115) ” 6.94, p # .05. When victim gender was known, offenders in the nonpsychopathic group committed homicides against males (48.4%) and females (47.3%) in approx- imately equal numbers, whereas offenders in the psychopathic group committed homicides more commonly against females (73.5%) than males (23.5%). Specific type of instrumental violence. Possible motives be-