Measuring Internalizing Psychopathology Using the MMPI-3: An Examination of Convergent, Discriminant, and Incremental Validity

Contemporary assessment of internalizing psychopathology emphasizes measuring transdiagnostic symptom dimensions rather than discrete diagnoses. The Minnesota Multiphasic Personality Inventory (MMPI) family of instruments includes broadband personality and psychopathology inventories that are particularly well-suited for assessing internalizing symptom dimensions. Although significant evidence exists supporting the validity of MMPI-2-Restructured Form (MMPI-2-RF) scale scores against mood disorders and related symptoms, the MMPI-3 contains new scales relevant to internalizing psychopathology and significant alterations to existing scales, necessitating a re-examination of substantive scale validity. The current study included 253 undergraduate students and 386 correctional inmates who completed the MMPI-3 and self-report measures of internalizing psychopathology. Correlational analyses were used to examine the convergent and discriminant validity of MMPI-3 scale scores against internalizing criteria, with results indicating that hypothesized convergent associations were of moderate-to-large effect sizes with smaller discriminant associations across both samples. Regression analyses were used to evaluate the incremental validity of MMPI-3 scale scores over MMPI-2-RF analogues in predicting internalizing outcomes, with MMPI-3 scale accounting for significant additional variance across criteria. Overall, findings generally support the convergent, discriminant, and incremental validity of MMPI-3 scales in measuring internalizing psychopathology. Exceptions to this general pattern of results, limitations, implications, and future research directions are discussed.