When doubting begins: exploring inductive reasoning in obsessive-compulsive disorder.

The objective of this study was to test the hypothesis that inductive reasoning plays a role in obsessional doubting by comparing an OCD sample with a non-OCD control group in performance of an inductive reasoning task. The 'Reasoning with Inductive Arguments Task' (RIAT) measures inductive performance using arguments drawn from both given vs. self-generated sources and containing neutral vs. OCD-related content. Both an OCD group recruited from clinical referrals and a control group recruited from the general population were compared on performance of the RIAT. People with OCD tended to doubt an initial conclusion much more than controls in the light of subsequent alternative conclusions given by the experimenter. There were no significant differences between the two groups in the self-generated condition. The OCD group doubted more regardless of whether the items were OCD-relevant or neutral. The control group also doubted the initial conclusions but not to the same extent as the OCD group in the 'given' condition and their degree of doubting did not differ between self-generated or given items. People with OCD may create doubt because they are giving too much credit to mental models given from external sources.

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.

Deductive and inductive reasoning in obsessive-compulsive disorder.

OBJECTIVES: 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. DESIGN: 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.

Treating delusional disorder: a comparison of cognitive-behavioural therapy and attention placebo control.

OBJECTIVE: Cognitive-behavioural therapy (CBT) has proved effective in treating delusions, both in schizophrenia and delusional disorder (DD). Clinical trials of DD have mostly compared CBT with either treatment as usual, no treatment, or a wait-list control. This current study aimed to assess patients with DD who received CBT, compared with an attention placebo control (APC) group. METHOD: Twenty-four individuals with DD were randomly allocated into either CBT or APC groups for a 24-week treatment period. Patients were diagnosed on the basis of structured clinical interviews for mental disorders and the Maudsley Assessment of Delusion Schedule (MADS). RESULTS: Completers in both groups (n = 11 for CBT; n = 6 for APC) showed clinical improvement on the MADS dimensions of Strength of Conviction, Insight, Preoccupation, Systematization, Affect Relating to Belief, Belief Maintenance Factors, and Idiosyncrasy of Belief. CONCLUSION: When compared with APC, CBT produced more impact on the MADS dimensions for Affect Relating to Belief, Strength of Conviction, and Positive Actions on Beliefs.