Similarity indices of the Dark Triad traits based on self and partner-reports: Evidence from variable-centered and couple-centered approaches

As the Dark Triad (DT) has been rarely examined from different rater perspectives, there is a lack of insight about important questions on assessment and understanding of these traits. The present study explores real similarity (assortment), reciprocity, assumed similarity and self-other agreement for the DT traits on 188 heterosexual romantic partners using self-reports and partner-reports. By using variable-centered and couple-centered approach and various analytic tools, moderate to high positive assortment was found for all DT traits, the highest for Machiavellianism. The levels of assumed similarity and self-partner agreement were similar or somewhat higher than those usually obtained for other personality traits. We discussed the implications of the results obtained concerning measurement and interpersonal relevance of the DT traits. •We examined four similarity indices of the Dark triad traits on romantic couples.•Self- and partner-reports, and variable- and couple-centered approach were used.•Positive assortment was found for all traits, the highest for Machiavellianism.•Assumed similarity and self-partner agreement were similar to other traits.•The results add to the understanding of interpersonal relevance of the Dark Triad.