Superstitious behaviors and beliefs in obsessive–compulsive disorder: An experimental investigation using the Illusory Contingency Task

Obsessive–compulsive disorder (OCD) is marked by the paradoxical coexistence of patients' ritualized actions and the patients' awareness of their lack of causal efficacy. The Illusory Contingency Task provides an experimental analogue for this ambivalence by inducing superstitious behaviors and beliefs under controlled conditions. We administered the Illusory Contingency Task to 75 participants (26 patients with OCD, 24 with anxiety disorders, and 25 healthy controls). In the task, participants moved a cartoon mouse on a 3 × 3 grid toward a piece of cheese, with success determined by a hidden time-based contingency (trial duration ≥4 s). We analyzed behavioral indices and participants’ explicit convictions based on illusory rules determining success. Contrary to our preregistered hypotheses, patients with OCD did not form stronger superstitious beliefs than controls. However, they achieved fewer successful trials than patients with anxiety disorders. Post hoc analyses indicated that this reduced success was associated with lower exploratory behavior. These findings suggest that patients with OCD have difficulty adapting problem-solving strategies under illusory contingencies and highlight the potential of the Illusory Contingency Task as a paradigm for studying the exploration–exploitation trade-off in OCD.