Individuals with obsessive-compulsive disorder (OCD) exhibit perseverative behaviours, like checking, to reduce uncertainty, but perseveration paradoxically enhances uncertainty. It is unclear what mechanism might be responsible. We hypothesised that perseverative OC-like behaviour produces "semantic satiation" and interferes with the accessibility of meaning. Healthy participants repeated 20 types of OC-like checking behaviour nonperseveratively (2 times) or perseveratively (20 times). Afterwards, they decided as quickly as possible whether a picture was semantically related to the checked object. The nonperseverative condition showed spreading of activation: Judgements were faster for related than for unrelated objects and pictures. The effect was blocked in the perseverative condition, where reaction times for related and unrelated items were similar. The results suggest that the ironic effects of compulsive perseveration are due to interference with spreading of activation.