Defense mechanisms and personality disorders: an empirical test of Millon's theory

The purpose of this study was to investigate Millon's hypothesized relationships between particular personality disorders and specific defense mechanisms. One hundred thirty psychiatric inpatients and outpatients, all diagnosed with an Axis II personality disorder, completed the Millon Clinical Multiaxial Inventory-II (MCMI-II; Millon, 1987) and the Defense Mechanism Inventory (DMI; Ihilevich & Gleser, 1986). Analyses revealed strong corroborating evidence for a number of the hypothesized relationships, including significant correlations between antisocial traits and acting out, obsessive-compulsive traits and reaction formation, paranoid traits and projection, passive-aggressive traits and displacement, and self-defeating traits and devaluation. There was also a trend suggesting the presence of a relationship between dependent personality traits and introjection. A factor analysis was also performed that suggested that method variance may be responsible for either lowered correlations between the MCMI-II and DMI or lack of significance for some predicted relationships. Results are discussed in terms of existing theory and research, and implications for treatment and future research are briefly addressed.