A research scale for the assessment of psychopathy in criminal populations

This paper describes an early phase in the development of new research scale for the assessment of psychopathy in criminal populations. The scale is meant to be a sort of operational definition of the procedures that go into making global ratings of psychopathy. While the interrater reliability of these ratings is very high ( > 0.85) they are difficult to make, require a considerable amount of experience, and the procedures involved are not easily communicated to other investigators. Following a series of analyses, 22 items were chosen as representative of the type of information used in making global ratings. Two investigators then used interview and case-history data to complete the 22-item checklist for 143 male prison inmates. The correlation between the two sets of total checklist scores was 0.93 and coefficient alpha was 0.88, indicating a very high degree of scale reliability. The correlation between the total checklist scores and global ratings of psychopathy was 0.83. A series of multivariate analyses explored the factorial structure of the scale and demonstrated its ability to discriminate very accurately between inmates with high and low ratings of psychopathy. Preliminary indications are that the checklist will hold up well to crossvalidation.