The evaluation of truthfulness in alleged sex offenders' self-reports: 16PF and MMPI validity scales.

Abstract

The evaluation of response bias (i.e., minimization or exaggeration) is central to forensic psychological evaluations. Yet few studies have assessed forensic samples to investigate the ability of psychological tests to detect response bias. We studied the relationship between the Sixteen Personality Factors Questionnaire (16PF) and the Minnesota Multiphasic Personality Inventory (MMPI) validity scales for 65 alleged sex offenders and assessed the effects of different cutoff scores for the 16PF validity scales. Results indicate consistent significant correlations between the validity scales of the 16PF and the MMPI for measures of minimization and exaggeration. use of a priori cutoff scores resulted in the classification of our sample in proportions parallel to those found in previous research for the 16PF Fake-Good scale but not the Fake-Bad scale. Our results indicate that 16PF validity scales are useful, but interpretations must take into account different base rates of response bias between sex offenders and the general population.