Iranian adaptation of the Epistemic Trust, Mistrust, and Credulity Questionnaire (ETMCQ): Validity, reliability, discriminant ability, and sex invariance

Introduction Epistemic trust, or trust in transmitted knowledge, has been proposed as a critical factor in psychopathology and psychotherapy. This study aimed at evaluating the psychometric properties of the Epistemic Trust, Mistrust, and Credulity Questionnaire (ETMCQ) in Iran. Method Data were collected from 906 participants. Along with the ETMCQ, measures of mentalizing, mindfulness, perspective‐taking, attachment, emotion dysregulation, and borderline personality disorder were administered. Confirmatory factor analysis and exploratory structural equation modeling (ESEM) were used to determine factorial structure. Results The ESEM model showed an acceptable fit and outperformed the confirmatory model. A 14‐item version of the ETMCQ was retained after examining item performance. Our findings also established criterion‐related validity for mistrust and credulity, an acceptable internal consistency for credulity, discriminant power for mistrust and credulity in detecting positive screens for borderline personality disorder, and measurement invariance across sexes. Conclusion This study provides evidence for the cross‐cultural applicability of the ETMCQ. Nonetheless, the validity of the trust and internal consistency of the mistrust subscale require particular attention in future research.