Background: Association Splitting (AS) is a novel cognitive technique, which has shown some promise for the reduction of obsessive thoughts in patients with obsessive-compulsive disorder (OCD). Its effect on unwanted intrusive thoughts (UITs) in the general population is yet unknown. Method: Our experimental study tested the effect of AS in 49 participants who reported UITs as a regular problem. Participants were randomly allocated either to an AS versus waitlist control (WL) condition. The White Bear Suppression Inventory (WBSI) was used for measuring changes over time. Results: Significant group differences were found across time. Relative to WL, AS exerted a positive effect on the reduction of UITs yielding a large effect size. According to self-report AS exerted a positive effect 6 days after the participants had initiated the exercises. All subjects in the AS condition judged the technique as effective Conclusion: Results suggest that AS could be a suitable intervention to help people with a potential vulnerability to a clinical problem to control their UITs.
