The problem of differential diagnosis by means of psychological tests has continuously engaged the efforts of clinical psychologists, although the results produced have not been consistent. This study sought to determine whether quantitative scores of the MMPI, Rorschach, and the Sixteen Personality Factor Test (16 PF) differentiate psychotic from neurotic outpatients. Ss were 25 psychotics and 38 neurotics, all of whom were male veterans receiving psychiatric treatment in an outpatient clinic. The psychotic Ss were almost entirely diagnosed as schizophrenics and the neurotic Ss were about equally divided between anxiety reactions and conversion reactions. All 3 tests were administered to all Ss by the same examiner. The MMPI (group form) and the 16 PF (Form A) were scored for the usual validity and personality scales, and the Rorschach was scored for the following categories: W, D, Dd, M, FM, F, FC, CF, P, H + Hd, A + Ad, At + X-ray, F+, all expressed as percentages, and R and number of cards rejected. Scoring followed the procedures of Klopfer and Kelley (1946). The neurotic group was significantly older than the psychotic one (MN = 43.55, SD = 5.83; MP = 36.92, SD 9.00) but both groups were equated for education (MN = 10.47, SD = 2.29; MP = 11.64, SD = 2.63). In addition, the neurotics were mostIy married and employed, while the reverse tended to apply to the psychotics. The frequency distributions of 10 of the 15 Rorschach variables were skewed and could not be normalized by logarithmic transformations. Although symmetrical distributions were obtained for percentages of W, D, F, P, and A + Ad, t tests for the differences between the means of the clinical groups failed to reach statistical significance. Analysis of the MMPI scales yielded significant t tests only for K, Hs, and Ma, and for the 16 PF test significant r tests were obtained only for Factors 0 (Confident vs Anxious) and Q4 (Composed vs Tense). Since only minor differences were found between psychotics and neurotics on the scales of the tests, average raw scores of each group on the MMPI were converted to T scores, and the scores on the 16 PF test were converted to stens to permit comparison of the test profiles. The profiles for both groups of Ss were remarkably similar. The MMPI profile of the neurotic group was slightly more highly elevated than that of the psychotic group, and on the 16 PF test both groups were within one sten unit of each other, except for Q4 on which the neurotics were 2 sten units higher than the psychotics. The general shape of the average MhPI profile of each group indicates neurotic psychopathology. The 16 PF profiles show that the psychotics are above the norm on Factors B, 0, and Q2 and that the neurotics are above the norm on 0, Qz, and Qr Both clinical groups are below the norm on C, El F, H, and Q,. These resulrs underscore the marked limitations of these tests when used for differential diagnosis of psychiatric patients. REFERENCES