Predicting DSM-IV cluster B personality disorder criteria from MMPI-2 and Rorschach data: A test of incremental validity

Despite their frequent conjoint clinical use, the incremental validity of Rorschach (Rorschach, 1921/1942) and MMPI (Hathaway and McKinley, 1943) data has not been adequately established, nor has any study to date explored the incremental validity of these tests for predicting Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]; American Psychiatric Association, 1994) personality disorders (PDs). In a reanalysis of existing data, we used select Rorschach variables and the MMPI PD scales to predict DSM-IV antisocial, borderline, histrionic, and narcissistic PD criteria in a sample of treatment-seeking outpatients. The correlational findings revealed a limited relation between Rorschach and MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, and Kaemmer, 1989) variables, with only 5 of 30 correlations reaching significance (p <. 05). Hierarchical regression analyses showed that both the MMPI and Rorschach data add incrementally in the prediction of DSM-IV borderline and narcissistic PD total criteria scores. The findings were less clear for the incremental value of Rorschach and MMPI-2 data in predicting the total number of DSM-IV histrionic PD criteria, which were best predicted by Rorschach data, and antisocial PD criteria, which were best predicted by MMPI-2 data. In addition to providing evidence of the incremental validity of Rorschach data, these findings also shed light on the psychological characteristics of the DSM-IV Cluster B PDs.