Abstract
A new self-report measure of mentalization, the 46-item Reflective Function Questionnaire (RFQ46), was investigated for reliability and validity. Relationships between borderline personality disorder (BPD), eating disorder (ED), impulsivity and mentalization were also explored. The RFQ46 was administered alongside a battery of conceptually-related questionnaires to 403 clinical and non-clinical participants. The clinical sample comprised patients attending specialist units for BPD and ED across 5 sites. A subset of these patients was interviewed to acquire diagnostic information. The non-clinical sample comprised staff and students from two colleges and one general hospital, the latter sample having been previously recruited in a pilot study. After initial data screening the RFQ46 was reduced to 15 items. An exploratory factor analysis revealed two conceptually coherent and internally reliable factors (of.75, .63), with an overall alpha of .77. The RFQ15 evidenced strong construct validity in that it positively related to measures of empathy and theory of mind, and negatively with ED, BPD, depression and impulsivity. ROC analysis supported the RFQ15’s power to discriminate between clinical and non-clinical populations. Comorbid patients appeared to have lower mentalization levels than patients with a single diagnosis. Anorexic, rather than bulimic attitudes were more closely related to mentalization. Mentalization was found to mediate the effect of multi-impulsivity on BPD and ED. Results suggest that mentalization can be effectively measured through self-report, and meaningful differences can be detected between clinical and non-clinical populations and between diagnostic categories. The present study’s results will assist future research into new mentalization-based treatments for BPD and ED.