title: Evidence accumulation in obsessive-compulsive disorder: the role of uncertainty and monetary reward on perceptual decision-making thresholds.
abstract: The compulsive behaviour underlying obsessive-compulsive disorder (OCD) may be related to abnormalities in decision-making. The inability to commit to ultimate decisions, for example, patients unable to decide whether their hands are sufficiently clean, may reflect failures in accumulating sufficient evidence before a decision. Here we investigate the process of evidence accumulation in OCD in perceptual discrimination, hypothesizing enhanced evidence accumulation relative to healthy volunteers. Twenty-eight OCD patients and thirty-five controls were tested with a low-level visual perceptual task (random-dot-motion task, RDMT) and two response conflict control tasks. Regression analysis across different motion coherence levels and Hierarchical Drift Diffusion Modelling (HDDM) were used to characterize response strategies between groups in the RDMT. Patients required more evidence under high uncertainty perceptual contexts, as indexed by longer response time and higher decision boundaries. HDDM, which defines a decision when accumulated noisy evidence reaches a decision boundary, further showed slower drift rate towards the decision boundary reflecting poorer quality of evidence entering the decision process in patients under low uncertainty. With monetary incentives emphasizing speed and penalty for slower responses, patients decreased the decision thresholds relative to controls, accumulating less evidence in low uncertainty. These findings were unrelated to visual perceptual deficits and response conflict. This study provides evidence for impaired decision-formation processes in OCD, with a differential influence of high and low uncertainty contexts on evidence accumulation (decision threshold) and on the quality of evidence gathered (drift rates). It further emphasizes that OCD patients are sensitive to monetary incentives heightening speed in the speed-accuracy tradeoff, improving evidence accumulation.
authors.affiliation: 1] Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK [2] PhD Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, Portugal [3] Institute for Biomedical Imaging and Life Sciences, University of Coimbra, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Banca
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Vestergaard
authors.affiliation: Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Vladan
authors.initials: V
authors.lastname: Rankov
authors.affiliation: Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Kwangyeol
authors.initials: K
authors.lastname: Baek
authors.affiliation: Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Mitchell
authors.affiliation: Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Tatyana
authors.initials: T
authors.lastname: Lapa
authors.affiliation: Institute for Biomedical Imaging and Life Sciences, University of Coimbra, Portugal.
authors.forename: Miguel
authors.initials: M
authors.lastname: Castelo-Branco
authors.affiliation: 1] Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK [2] Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, UK [3] Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK.
authors.forename: Valerie
authors.initials: V
authors.lastname: Voon
mesh_terms: D000328:Adult; D003220:Conflict, Psychological; D003657:Decision Making; D005260:Female; D006801:Humans; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000188:drug therapy / Q000523:psychology*; D011581:Psychological Tests; D011930:Reaction Time; D012044:Regression Analysis; D012201:Reward; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use; D035501:Uncertainty; D014796:Visual Perception
chemical_list: D017367:Selective Serotonin Reuptake Inhibitors