The schizophrenia-organicity (Sc-o) and psychiatric-organic (P-O) MMPI scales: A review

Abstract

Reviewed the research on the MMPI Schizophrenia‐Organicity (Sc‐O) and Psychiatric‐Organic (P‐O) Scales, measures developed to separate brain‐damaged patients from schizophrenics and from functional psychiatric patients as a whole. Over 10 cross‐validations, the average Sc‐O scale hit rate has been 69%, which suggests that it is a better differentiator of braindamaged from schizophrenic males than most popular ability‐based organicity tests. Hit rates for five studies that contrasted organic and psychiatric patients on the P‐O scale also averaged 69%. The scales appear to be useful in both medical and psychiatric hospitals, but their validities in female samples are not well established. A system for making diagnostic decisions from ability and personality measures in combination is described, and evidence is cited that it improves on the hit rates achieved by either type of test alone.

Relative efficacy of the SC-O, P-O, P-N, and SC MMPI scales in differentiating brain-damaged, brain-damaged schizophrenic, schizophrenic, and somatoform disorders in an outpatient setting

“…The P-0 scale's success in differentiating the schizophrenic from the brain-damaged groups in both the matched and unmatched conditions suggests that it is the MMPI scale of choice in differentiating schizophrenic and brain-damaged outpatient groups. This finding is consistent with previously cited findings with inpatients that demonstrated the value of the P-0 scale for answering this question (Watson, 1984). Similarly, it appears that the Sc scale has particular value when outpatient brain-damaged schizophrenics are to be differentiated from either outpatient brain-damaged subjects or schizophrenics.…”

“…This was noteworthy because the Sc-0 scale had been found to be significant in the unmatched condition. As noted by Watson (1984), this scale has been cross-validated more than 10 times in studies with inpatient populations. Similarly, the P-N scale, which had been twice cross-validated (Dodge & Kolstoe, 1971; Schwartz & Brown, 1973), failed to differentiate significantly the somatoform group from the brain-damaged group.…”

“…The special scales are the Schizophrenia-Organicity scale (Watson, 1971), the Psychiatric-Organic (P-0) scale (Watson & Plemel, 1978), the Pseudo-Neurological (P-N) scale (Shaw & Matthews, 1965). The Sc-0 scale was developed to differentiate organic from schizophrenic patients and has proved successful in 10 crossvalidation studies (Watson, 1984). By contrast, the P-0 scale was developed to separate organics from all types of functional disorders (e.g., schizophrenia, alcoholism, and neurosis).…”

Prediction of recovery for closed-head-injured adults: An evaluation of the MMPI, the adaptive behavior scale, and A “Quality of Life” rating scale

“…The MMPI has been used extensively in research with the head injured over the years with the goal of improving the ability of the instrument to differentiate "organic" from "functional" psychological problems (Carpenter & LeLieuvre, 198 1 ;Dikmen, 1973;Graca, Hutzell, Gaffney, & Whiddon, 1984;Horton, 1982;Horton & Timmons, 1982;Sillitti, 1982;Watson, 1984;Wooten, 1983aWooten, , 1983b. Researchers still grapple with the problem and differ over the validity of the term "organicity," the response style of the head-injury victim, and the usefulness of the instrument among subjects who exhibit fatigue and poor concentration.…”