Obsessions and compulsions in the lab: A meta-analysis of procedures to induce symptoms of obsessive-compulsive disorder.

Efficacious induction procedures of symptoms of obsessive-compulsive disorder (OCD) are necessary in order to test central tenets of theories on OCD. However, the efficacy of the current range of induction procedures remains unclear. Therefore, this meta-analysis set out to examine the efficacy of induction procedures in participants with and without OCD symptoms. Moreover, we explored whether the efficacy varied across different moderators (i.e., induction categories, symptom dimensions of OCD, modalities of presentation, and level of individual tailoring). In total we included 4900 participants across 90 studies. The analyses showed that there was no difference in studies using subclinical and clinical participants, confirming the utility of analogue samples. Induction procedures evoked more symptoms in (sub)clinical OCD than in healthy participants, which was most evident in the contamination symptom dimension of OCD. Analysis within (sub)clinical OCD showed a large effect size of induction procedures, especially for the threat and responsibility category and when stimuli were tailored to individuals. Analysis within healthy participants showed a medium effect size of induction procedures. The magnitude of the effect in healthy individuals was stronger for mental contamination, thought-action fusion and threat inductions.