OBJECTIVE: Various factor structures have been suggested for the Davos Assessment of Cognitive Biases (DACOBS) and the Cognitive Biases Questionnaire for Psychosis (CBQ-P), assessing cognitive bias, necessitating additional validation in diverse languages to enhance the validity of the scales. METHOD: Persian versions of these scales were validated within an Iranian cohort comprising 1719 individuals: patients with schizophrenia (n = 334) and major depressive disorder (MDD
n = 346) and a non-clinical group (n = 1039). The participants completed both self-report and clinician-administered assessments. RESULTS: The 18-item DACOBS version, comprising four factors, and the single-factor structure of the CBQ-P exhibited the optimal model fit, with confirmed reliability. Both scales showed significant correlations with constructs such as paranoid ideation, social cognition, schizotypal personality and positive symptoms. Additionally, the scales differentiated patients with schizophrenia and individuals at high risk for psychosis from those at low risk or patients with MDD. The CBQ-P and certain subscales of the DACOBS predicted susceptibility to psychosis, positive symptoms and psychosis-related manifestations. CONCLUSIONS: The research highlights the validity and reliability of the Persian adaptations of the 18-item DACOBS and the CBQ-P for evaluating cognitive bias in individuals diagnosed with schizophrenia and for identifying individuals at an elevated risk for psychosis.