Does the Dark Triad Manifest Similarly in men and Women? Measurement Invariance of the Dirty Dozen across sex

The Dark Triad is a constellation of three socially undesirable personality traits: narcissism, psychopathy, and Machiavellianism. Previous research has shown that men tend to score higher than women on Dark Triad scales, but the validity of these results is questionable as there is no evidence that the scales used exhibit measurement invariance across sex in the adult population. Here, we report four studies assessing the measurement invariance across sex of a recently developed, concise measure of the Dark Triad, namely Jonason and Webster's (2010) Dirty Dozen (DD). As no validated Italian version of the DD was available, we developed an Italian version and assessed its psychometric properties. Studies 1 to 3 revealed that the Italian DD had adequate psychometric properties, and replicated the three-factor structure and the nomological network of the original version. Study 4 provided evidence of the measurement invariance of the DD across sex, such that men scored higher than women with respect to psychopathy, Machiavellianism, and, to a lesser extent, narcissism. These findings indicate that the DD can be used to provide reliable assessments of sex differences in Dark Triad traits. Furthermore, the results of sex comparisons are consistent with a biosocial approach to social role theory that assumes that being agentic rather than communal is considered desirable for men and undesirable for women.