The Pathological Narcissism Inventory (PNI, Pincus et al.,
2009) is a 52-item self-report measure designed to assess grandiose and vulnerable expressions of pathological narcissism, common to treatment seeking clients. Recently, briefer versions (28-item, 12-item) were derived and appeared to produce similar associations with important outcomes (Schoenleber et al.,
2015), but research is lacking for how different PNI forms relate to interpersonal dysfunction. Moreover, there is little research examining how PNI based grandiosity and vulnerability relate to interpersonal dysfunction using an interpersonal construct validation approach (i.e. structural summary method, SSM). In a sample of 1526 undergraduate students, PNI scales were examined using the SSM, finding few meaningful differences across different PNI forms, indicating little is lost by using briefer forms. However, compared to other narcissism measures, the PNI was more consistently related to interpersonal distress and hypersensitivity, and evinced different interpersonal themes for grandiosity and vulnerability compared to trait-based measures. We discuss the implications of these findings toward advancing the assessment of narcissism.
