Deductive and inductive reasoning in obsessive-compulsive disorder.
OBJECTIVE
This study tested the hypothesis that people with obsessive-compulsive disorder (OCD) show an inductive reasoning style distinct from people with generalized anxiety disorder (GAD) and from participants in a non-anxious (NA) control group.


METHODS
The experimental procedure consisted of administering a range of six deductive and inductive tasks and a probabilistic task in order to compare reasoning processes between groups.


METHODS
Recruitment was in the Montreal area within a French-speaking population. The participants were 12 people with OCD, 12 NA controls and 10 people with GAD. Participants completed a series of written and oral reasoning tasks including the Wason Selection Task, a Bayesian probability task and other inductive tasks, designed by the authors.


RESULTS
There were no differences between groups in deductive reasoning. On an inductive "bridging task", the participants with OCD always took longer than the NA control and GAD groups to infer a link between two statements and to elaborate on this possible link. The OCD group alone showed a significant decrease in their degree of conviction about an arbitrary statement after inductively generating reasons to support this statement. Differences in probabilistic reasoning replicated those of previous authors.


CONCLUSIONS
The results pinpoint the importance of examining inference processes in people with OCD in order to further refine the clinical applications of behavioural-cognitive therapy for this disorder.
Pélissier
Marie-Claude
MC
Centre de Recherche Fernand-Seguin, 7331 Hochelaga, Montréal, Québec, H1N 3V2, Canada. mcpelissier@crfs.umontreal.ca
O'Connor
Kieron P
KP
D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008128:Logic; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000523:psychology*; D011336:Probability; D011792:Quebec; D013850:Thinking