An examination of the Dirty Dozen measure of psychopathy: a cautionary tale about the costs of brief measures.

Given substantial interest in the traits conceived of as part of the "Dark Triad"--psychopathy, narcissism, and Machiavellianism--assessment of these traits is of great importance. The Dirty Dozen (DD; Jonason & Webster, 2010) is a brief measure of the Dark Triad constructs that uses 4 items to assess each of these constructs. In the present study, the authors examined the adequacy of the DD's Psychopathy scale by comparing it with established measures of psychopathy in a sample of undergraduates (Sample 1: N = 789) and male prisoners (Sample 2: N = 75). DD's Psychopathy subscale manifested significant correlations with established measures, but the correlations were smaller than those evinced by the existing scales. The results also demonstrated that there is important variance related to interpersonal antagonism and disinhibition that is not assessed by the DD. The authors suggest that caution should be used in relying on the DD as a measure of psychopathy.