Abstract
The popularity of the Minnesota Multiphasic Personality Inventory (MMPI; Hathaway & McKinley, 1940), MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) and the Rorschach in the assessment of psychopathology in applied settings have been well established (Archer & Krishnamurthy, 1993b; Greene, 2000). Although it might be expected that the MMPI and the Rorschach would be interrelated, a review of the literature revealed little congruence between these two widely used assessment measures (Archer & Krishnamurthy, 1993a, 1993b; Ganellen, 1996a, 1996b, 1996c; Meyer, 1996; Meyer, 1997; Meyer, Riethmiller, Brooks, Benoit, & Handler, 2000). The general goal of this study was to contribute to the understanding of the relationship between the MMPI-2 and the Rorschach variables related to psychosis in a clinical population of adults. To accomplish this goal, the current study was broken down into two specific goals. . First, following previous convention (Meyer, 1997; Meyer et al., 2000), this study examined the effect of test interaction styles on the interrelationships between the MMPI-2 and the Rorschach on psychotic-related indices. Second, this study examined the incremental validity and the clinical utility of the MMPI-2 and Rorschach with regard to differential diagnosis in a sample of adult inpatients with a primary psychotic disorder (PPD) or a primary mood disorder without psychotic features (PMD). Results indicate that grouping patients according to test-interaction style, in the form of being either dilated or constricted when responding to the task, had minimal impact in the predicted direction on the level of convergence between the MMPI-2 and Rorschach. When test interaction styles were ignored, there were modest significant correlations between the MMPI-2 Sc and BIZ scales and the Rorschach PTI. Similarly when patients approached each test with a similar style, there were modest significant positive correlations between the MMPI-2 Sc and BIZ scales and the Rorschach PTI. When patients approached the test in an opposing manner, the MMPI-2 scales and the Rorschach variables tended to be negatively correlated. Despite significant correlations between the MMPI-2 Sc and BIZ scales and the Rorschach PTI, these correlations were small in magnitude, and were not consistent with those reported by Meyer et al. (2000) and Lindgren and Carlsson (2002). On its own, the PTI showed a better overall classification rate than the MMPI-2. The PTI was able to correctly classify PPD and PMD patients 84% of the time as compared to 70% when the MMPI-2 variables were used. To assess the clinical utility of the MMPI-2 and Rorschach in differentiating psychotic patients from nonpsychotic patients, diagnostic efficiency statistics were computed at each block of the hierarchical regression analyses. When the MMPI-2 variables were entered first into the analyses, diagnostic efficiency statistics indicated that the addition of the Rorschach PTI contributed to the prediction of group membership above what was predicted by the MMPI-2 variables. When the Rorschach PTI was entered first into the analyses, diagnostic efficiency statistics showed that the MMPI-2 scales were not able to add to the predictive capacity of the Rorschach.
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