Thought-fusion beliefs' independent causal effects on obsessive-compulsive symptoms: Evidence from experimental...

This study examined, using a laboratory paradigm, whether activating thought-fusion beliefs has an immediate effect on obsessive-compulsive-like symptoms, namely discomfort and behavioral responses to neutral intrusive thoughts, independent of cognitive self-consciousness, and assessed its clinical specificity.

A 2 (group, patients with OCD vs. healthy control) × 3 (experimental condition, thought-fusion beliefs plus cognitive self-consciousness vs. cognitive self-consciousness alone vs. control) mixed-design experiment was conducted (n = 108). Variables were manipulated using a fake electroencephalogram (EEG) and verbal instructions. Primary outcome measures were the frequency of intrusions related to target thoughts (water or drinking) and the discomfort associated with these intrusions. Secondary outcomes included effort to control intrusions and time spent thinking about them. Data were analyzed using covariance and generalized linear models, controlling for anxiety and depression.

A significant group × condition interaction was found for discomfort associated with intrusions. Within the patient group, Condition 1 produced significantly greater discomfort than Condition 2 and the control condition, with Condition 2 also exceeding the control condition. For intrusion frequency, only a main effect of condition was observed, with both experimental conditions exceeding the control condition. Significant group × condition interactions were also found for both secondary measures, with the pattern (Condition 1 > Condition 2 > Control) most pronounced in the patient group.

Under controlled conditions with standardised stimuli, thought-fusion beliefs independently and specifically amplify distress associated with intrusive thoughts in patients with OCD and increase control-related responses.