Applying the Defense Mechanisms Rating Scales Q-sort to assess patients' level of overall defensive functioning in interview data: validity and reliability.

The observer-rated Q-sort based on the gold-standard Defense Mechanisms Rating Scales (DMRS-Q) allows the investigation of defense mechanisms based on one session as a whole. The present study analyzed the reliability and validity of the DMRS-Q applied to three types of clinical interactions other than therapy sessions. Transcripts of three different clinical interviews, including a total of 233 adults (50 cancer patients who completed Mayman's Early Memory Interview [EMI], 93 individuals without clinical diagnosis who completed McAdams' Life Story Interview [LSI], and 90 pregnant women who completed the Working Model of the Child Interview [WMCI]), have already been coded on the DMRS. Our research team of expert raters conducted the DMRS-Q coding on these same transcripts and assessed the inter-rater reliability and the concurrent, convergent, and discriminant validity of DMRS-Q in these clinical interactions. Results showed good inter-rater reliability (intraclass correlation coefficient [ICC]=.70) for the Overall Defensive Functioning (ODF), although lower than reported using transcripts of psychotherapy sessions. Large correlations were found between ODF scales assessed with the DMRS-Q and the DMRS among the three samples (r=.43 to .59; p<.001), while small to moderate correlations were found between the DMRS-Q, sociodemographic, and psychological measures. The DMRS-Q ODF scale might be a valid and reliable measure to assess the overall maturity of defensive functioning in brief interviews. Its ease of use, supported by open-source software, enables the application of the gold-standard DMRS theory across a wide range of contexts beyond psychotherapy research.