Validation of the cognitive fusion questionnaire in regular meditators and persons with schizophrenia spectrum disorders

Cognitive fusion, a key construct in Acceptance and Commitment Therapy (ACT), describes the overidentification with internal thoughts that compromises psychological flexibility and contributes to maladaptive emotion regulation. Cognitive defusion techniques aim to reduce this entanglement, promoting adaptive functioning and improved mental health. This study examined the psychometric properties of the Cognitive Fusion Questionnaire (CFQ) across diverse populations, focusing on reliability, validity, and sensitivity to change. Data were drawn from three studies involving individuals with schizophrenia spectrum disorders (SSD) and non‐clinical meditators. In Study 1, regular meditators (N = 779) completed the original English CFQ. Study 2 assessed the German version (CFQ‐D) in patients with SSD (N = 123). Study 3, a randomized controlled trial (N = 38), evaluated the CFQ‐D's sensitivity to mindfulness‐based group therapy (MBGT). Internal consistency, correlations with the Southampton Mindfulness Questionnaire (SMQ), and pre‐post changes were analyzed. The English CFQ showed excellent internal consistency (α = 0.94) and strong negative correlations with the SMQ (r = ‐0.67). The CFQ‐D demonstrated high reliability (α = 0.92) and moderate negative correlations with SMQ (r = ‐0.30). In Study 3, participants receiving mindfulness‐based therapy showed reduced cognitive fusion over time. The CFQ is a reliable, valid measure of cognitive fusion across clinical and non‐clinical samples.