Date of Award

1-29-1971

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

Abstract

The present investigation attempted to extend the psychophysical analogy to the study of clinical judgment on the MMPI. Previous judgmental research has dealt with multidimensional diagnosis or with simulation of clinicians' judgments on the MMPI. It was believed that the previous research examining the process of clinical judgment had not employed sufficiently sensitive methodologies. Therefore, in this study both direct estimation procedures and classical psychophysical methods were employed in an effort to describe and quantify directly the relationship between clinical judgment and the MMPI. These methods, particularly the former, have been demonstrated to be beneficial to use when exploring the topic of clinical judgment.

Thirty-two Ph.D. clinical psychologists from Minnesota and Kansas served as judges. They made magnitude estimations (with assigned modulus) concerning the degree of importance of the ten MMPI basic scales and the degree of pathology evidenced by T-scores (30 to 110) on each basic scale. Judges also indicated a T-score for each basic scale which represented an equal degree of pathology across all scales. The method of constant stimuli was employed to determine a score for each validity scale which might invalidate the overall profile.

In general, results indicated that judges displayed low agreement on the degree of pathology associated with T-scores below 50 for each basic scale. Minnesota judges tended to view lower scores as less pathological than did Kansas judges. For T-scores above 50 on each scale, perceived pathology was curvilinearly related to the appropriate stimulus metric. A log-log transformation rectified the data in a linear manner, suggesting that power functions could provide an adequate description of the data. T-scores above 50 on each scale were arranged in three clusters according to perceived pathology. These clusters were seen to differ from formally suggested interpretive groupings. Judgments of importance for the basic scales could be typified by three clusters which were compared with previous findings. Judges were unable to equate T-scores accurately across scales for degree of pathology, and implications of this result were discussed. Validity thresholds were able to be determined for only three validity scales, and this result was discussed in reference to interpretive manuals.

Limitations of the present study were discussed, e.g., the judgmental groups were not homogeneous, and the task presented restricted the generality of the obtained results.

The implications of the present study include: (1) it represents an extension of the psychophysical analogy to the present area, (2) it offers an initial effort to provide a succinct, graphic presentation of clinical judgment on the MMPI which may enhance formal training, and (3) it provides a variety of future research suggestions; for example, the further investigation of the meaning of low T-scores on the basic scales.

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