Inductive and deductive reasoning in Obsessive-Compulsive Disorder


This study examined the hypothesis that individuals with obsessive-compulsive disorder (OCD) show a selective deficit in inductive reasoning but are unimpaired in their ability to make deductive inferences. 100 participants from an analog sample made inductive or deductive inferences about arguments that differed according to causal consistency and validity. They also completed a task examining sensitivity to the implications of diverse evidence in induction. Participants who were high or low on obsessive-compulsive symptoms showed similar patterns of induction based on causal knowledge and similar patterns of deduction. However, those with the highest level of OCD symptoms showed less of a preference for diverse evidence when evaluating inductive arguments, compared to those with the lowest level of symptoms. This difference was found across both OCD-relevant and OCD-neutral items, and persisted when the effects of group differences in general ability were controlled. These results indicate that both inductive reasoning based on background knowledge and deductive reasoning are intact in individuals with high OCD-traits but the use of inductive heuristics such as evidence diversity is impaired.

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