The (mis)measurement of the Dark Triad Dirty Dozen: exploitation at the core of the scale

Abstract

Background. The dark side of human character has been conceptualized in the Dark Triad Model: Machiavellianism, psychopathy, and narcissism. These three dark traits are often measured using single long instruments for each one of the traits. Nevertheless, there is a necessity of short and valid personality measures in psychological research. As an independent research group, we replicated the factor structure, convergent validity and item response for one of the most recent and widely used short measures to operationalize these malevolent traits, namely, Jonason's Dark Triad Dirty Dozen. We aimed to expand the understanding of what the Dirty Dozen really captures because the mixed results on construct validity in previous research. Method. We used the largest sample to date to respond to the Dirty Dozen (N = 3,698). We firstly investigated the factor structure using Confirmatory Factor Analysis and an exploratory distribution analysis of the items in the Dirty Dozen. Secondly, using a sub-sample (n = 500) and correlation analyses, we investigated the Dirty Dozen dark traits convergent validity to Machiavellianism measured by the Mach-IV, psychopathy measured by Eysenck's Personality Questionnaire Revised, narcissism using the Narcissism Personality Inventory, and both neuroticism and extraversion from the Eysenck's questionnaire. Finally, besides these Classic Test Theory analyses, we analyzed the responses for each Dirty Dozen item using Item Response Theory (IRT). Results. The results confirmed previous findings of a bi-factor model fit: one latent core dark trait and three dark traits. All three Dirty Dozen traits had a striking bi-modal distribution, which might indicate unconcealed social undesirability with the items. The three Dirty Dozen traits did converge too, although not strongly, with the contiguous single Dark Triad scales (r between .41 and .49). The probabilities of filling out steps on the Dirty Dozen narcissism-items were much higher than on the Dirty Dozen items for Machiavellianism and psychopathy. Overall, the Dirty Dozen instrument delivered the most predictive value with persons with average and high Dark Triad traits (theta > -0.5). Moreover, the Dirty Dozen scale was better conceptualized as a combined Machiavellianism-psychopathy factor, not narcissism, and is well captured with item 4: 'I tend to exploit others towards my own end.' Conclusion. The Dirty Dozen showed a consistent factor structure, a relatively convergent validity similar to that found in earlier studies. Narcissism measured using the Dirty Dozen, however, did not contribute with information to the core of the Dirty Dozen construct. More importantly, the results imply that the core of the Dirty Dozen scale, a manipulative and anti-social trait, can be measured by a Single Item Dirty Dark Dyad (SIDDD).

Keywords: Dark Triad Dirty Dozen; Dark triad; Gender; Item response theory; Machiavellianism; Narcissism; Psychopathy; Single item dirty dark triad.

Figure 1. Bi-factor model of Dirty Dozen.

N = 3,698. NFI = .98, CFI = .98, RMSEA = .05.

Figure 2. Frequency distributions showing the bi-modality of the three Dirty Dozen Dark Triad traits.

N = 3,698. The numbers on the y-axis represent the proportion of replies for each Likert-category (1–7) on the x-axis. For instance, 47% of total replies on DD psychopathy items were placed on the lowest option (1) “strongly disagree,” which depicts the skewness in response pattern.

Figure 3. Total information curve on the latent core of the dark triad dirty dozen.

Overall, the Dirty Dozen instrument delivers the most predictive value with persons with average and high Dark Triad traits (theta > −0.5).

Figure 4. Scale information curves depicting the information content in each respective sub factor.

Figure 5. Item information curves for each of the 12 items of the Dirty Dozen.

Note that item 1 (Manipulate) and 4 (Exploit) deliver the most information on the latent Dark Triad (labeled theta). Item 8 (Cynicism) delivers the least information. Furthermore, the three first items on narcissism (9–11) don’t deliver much predictive information (flat curves, cf. earlier CFA bi-factor model) to the overall Dark Triad trait—However, an IRT with only the narcissism items confirms that these predict the latent trait (theta, i.e., narcissism) very satisfactorily (cf. earlier CFA hierarchical model).