RESUMEN
BACKGROUND: Cognitive models of obsessive-compulsive disorder attribute a causal role to maladaptive beliefs. AIMS: To test this hypothesis, we manipulated Overimportance of Thoughts (OT) beliefs and experimentally evaluated their effect on the response to an induced aggressive impulse. METHOD: Eighty-five participants completed a battery of self-report instruments assessing obsession symptoms, thought control, affectivity and obsessive beliefs, and were then randomly assigned to two conditions. In the experimental condition participants read a scientific abstract on the importance of thought control whilst those in the control condition read a neutral abstract. All participants identified a loved person and imagined feeling the impulse to stab this person, then completed again OT beliefs measures (Overimportance of Thought, Moral-Thought Action Fusion and Thought Action Fusion Likelihood). RESULTS: The Moral component of the Thought Action Fusion was reduced by reading a brief text about the possibility and desirability of thought control. However, experimentally induced changes in beliefs did not yield differences in the intrusiveness of the aggressive impulse. CONCLUSIONS: Some beliefs can be modified through a single session in which information similar to what could be obtained in quotidian life is provided.