The Effectiveness of Acceptance and Commitment Therapy on Cognitive Bias and Dysfunctional Attitudes of Adolescents with Obsessive Beliefs

Objective: This study aimed to evaluate the effectiveness of Acceptance and Commitment Therapy (ACT) in reducing cognitive bias and dysfunctional attitudes among adolescent girls with obsessive beliefs.

Methods and Materials: A quasi-experimental, pretest–posttest control group design was employed. From a population of 500 female secondary school students in Tehran during the 2023–2024 academic year, 30 students with high scores on the Obsessive Beliefs Questionnaire (OBQ-44) were selected via multistage cluster sampling and randomly assigned to either an ACT intervention group (n = 15) or a waitlist control group (n = 15). The intervention group received ten 90-minute ACT sessions based on Hayes et al.’s protocol. Outcome measures included the OBQ-44, the Cognitive Bias Questionnaire (CBQ), and the Dysfunctional Attitudes Scale (DAS-26). ANCOVA was used to analyze data following assumption testing.

Findings: ANCOVA results indicated statistically significant reductions in both cognitive bias (F = 44.32, p < .001, η² = 0.541) and dysfunctional attitudes (F = 83.91, p < .001, η² = 0.763) in the ACT group compared to the control group. All statistical assumptions, including normality, homogeneity of variances, and regression slope equality, were satisfied. Post-test mean scores of the ACT group were significantly lower in both outcome measures.

Conclusion: ACT significantly reduced maladaptive cognitive patterns and dysfunctional attitudes in adolescents with obsessive beliefs. Its integration in school-based mental health programs may offer an effective strategy for enhancing psychological flexibility and resilience in youth.