Cross-national differences in the assessment of psychopathy: do they reflect variations in raters' perceptions of symptoms?

Cross-national differences in the prevalence of psychopathy have been reported. This study examined whether rater effects could account for these differences. Psychopathy was assessed with the Psychopathy Checklist-Revised (PCL-R; R. D. Hare, 1991). Videotapes of 6 Scottish prisoners and 6 Canadian prisoners were rated by 10 Scottish and 10 Canadian raters. No significant main or interaction effects involving the nationality of raters were detected at the level of full scores or factor scores. Using a generalizability theory approach, it was demonstrated that the interrater reliability of total scores was good, that is, the proportion of variance in test scores attributable to raters was small. The interrater reliability of factor scores was lower, typically falling in the fair range. Overall, the results suggest that the reported cross-national differences are more likely to be in the expression of the disorder rather than in the eye of the beholder.