The present study investigated the validity of the Pe (Toobert, Bartelme, & Jones, 1959) and Sexual Deviancy (Marsh, Hilliard, & Liechti, 1955) subscales, developed from the MMPI, to determine if the scales would discriminate convicted sexual offenders from nonsexual offenders.

The MMPI has been used extensively for the clinical assessment of deviancy among sexual offenders. In order to derive a diagnostic scale for the specific identification of male incest offenders, an item analysis, using MMPI data from offenders, compared MMPI data from a nonoffending control sample. The item analysis results were cross validated with MMPI data from a separate sample of incest offenders. Eleven MMPI items were found to be critical in discriminating male incest offenders from nonoffenders, and these items comprise the Ic experimental scale. On the basis of the Ic scale, male incest offenders evidence characterological disturbances in the form of pervasive feelings of psychological and social inadequacy.