Inductive reasoning and doubt in obsessive compulsive disorder.

BACKGROUND AND OBJECTIVES: Previous studies show that individuals with obsessive compulsive disorder (OCD) accord more importance than healthy controls (HC) to alternative conclusions, resulting in increased doubt regarding an initial conclusion. The goal of the present study was to replicate and extend this finding.

METHODS: Eighteen participants diagnosed with OCD and 16 HC completed the Reasoning with Inductive Arguments Task (RIAT), which operationalizes doubt as change in confidence towards a conclusion after alternative conclusions are presented. To examine conditions that facilitate doubt, the impact of alternative conclusions that both supported and contradicted the initial conclusion was compared, as well as the effect of neutral and OCD-relevant item content.

RESULTS: Both the OCD and HC groups decreased confidence after contradicting conclusions, but only the HC group increased confidence when presented with supporting conclusions. Furthermore, decrease in confidence in the OCD group correlated with OCD symptom severity.

LIMITS: The RIAT could be adapted to better take into account of OCD subtypes.

CONCLUSION: Doubt generation may contribute to obsessional doubting.