MMPI profiles of males accused of severe crimes: a cluster analysis

Abstract

In studies attempting to classify criminal offenders by cluster analysis of Minnesota Multiphasic Personality Inventory-2 (MMPI-2) data, the number of clusters found varied between 10 (the Megargee System) and two (one cluster indicating no psychopathology and one exhibiting serious psychopathology). The latter results raise doubts about the suitability of the MMPI-2 for classification in forensic settings. The present study aimed at deriving an empirical classification system using cluster analysis of 247 MMPI-2 profiles of pretrial criminal defendants in a forensic psychiatric observation clinic. Results indicated only a ‘non-disturbed’ and a ‘disturbed’ profile, differing on general elevation of MMPI-2 profiles but displaying no qualitatively distinct profiles. The clusters differed on age at admission and first conviction, indicating a late onset of criminal activity for disturbed offenders. Also, the clusters differed significantly on Axis I diagnosis and borderline significantly on Axis II diagnosis. The absence of distinct personality profiles between the clusters suggests restricted usefulness of the MMPI-2 in a forensic context of diverse and severe psychopathology and serious crimes. Either the investigated population is in fact extremely homogeneous, truly comprising only two kinds of offenders, or the types of offenders in these populations are not effectively distinguished by the MMPI-2.