Self- and informant-based comparison of Dark Triad scales in German adults

Self-report measures are the standard for assessing Dark Triad personality traits—narcissism, Machiavellianism, psychopathy. When informant-report measures are used, they are usually created as ad hoc adaptations of the self-report scales, lacking transparent documentation and evidence of validity. To fill this gap, we systematically created other-report adaptations of established Dark Triad personality measures—the Narcissistic Admiration and Rivalry Questionnaire, the Mach-IV scale, the Self-Report Psychopathy Scale-III, the Short Dark Triad, and the M7P7 scale—and compared their self-other invariance, self-other correlations, and criterion validity. Self-report versions were administered to 402 individuals (75% women, mean age = 28 years, highly educated, predominantly white). Informant-report versions were administered to close informants nominated by the targets (Ndyads = 335). We found (1) that self-report and informant measures yielded the same latent structure, but that the strict invariance assumption was violated to varying degrees by the different scales. (2) All scales yielded large self-other correlations with no significant differences between scales. (3) The informant-report measures were about as strongly associated with preregistered outcome variables as the self-report measures, with only minor differences between scales. In conclusion, all scales are suitable for informant-report assessment of the Dark Triad, but some scales do not allow valid comparisons of self- and other-report mean scores.