Therapeutic Mentalization in Group Therapy: Development and Preliminary Validation of a Measure of Experienced Mentalization

Our paper reports on the development and psychometric properties of the Therapeutic Mentalization Scale for Group Therapy (TMS-GT). The TMS-GT is an 11-item self-report measure designed to assess individuals' experiences of having been mentalized in group therapy. Two combined samples of adults (n = 157; M_age = 28.4, SD = 12.1) participating in separate outpatient group psychotherapy treatments completed the TMS-GT posttreatment, with a subsample (n = 87) completing the TMS-GT again 3 months later and the other subsample (n = 70) completing measures of group psychotherapy processes and psychiatric symptoms. Multilevel exploratory factor analysis identified the two-factor structure of the TMS-GT, reflecting two dimensions of the experience of having been mentalized: mentalized attunement and mentalized continuity. The two subscales demonstrated adequate internal consistency and temporal stability. Moreover, additional psychometric findings provided further support for the validity of the TMS-GT. Overall, preliminary analyses suggest that the TMS-GT appears to be a reliable and valid measure of the experience of being mentalized among adults participating in outpatient group therapy.