title: Dopaminergic modulation of probabilistic reasoning and overconfidence in errors: a double-blind study.
abstract: BACKGROUND
  Reasoning biases such as jumping to conclusions (JTC) and overconfidence in errors have been well replicated in patients with delusions. However, their relation to dopaminergic activity, central to pathophysiologic models of psychosis, has not yet been investigated. This study aimed to examine the effects of a dopaminergic agonist (L-dopa) and a dopaminergic antagonist (haloperidol) on the JTC bias and overconfidence in errors after single-dose administration in healthy individuals.
  
  
  METHODS
  The study used a randomized, double-blind, placebo-controlled, 3-way crossover design. Participants were 36 healthy individuals aged 18-36 years. The variables of interest were draws to decision and probability threshold to decision on a computerized variant of the beads task and the number of high-confident incorrect responses on a visual memory task.
  
  
  RESULTS
  There were no significant effects of substance on draws to decision and probability threshold to decision. A significant effect emerged for high-confident incorrect responses in the memory task; pairwise comparisons indicated a significant reduction of the number of high-confident incorrect responses after administration of haloperidol vs l-dopa and placebo.
  
  
  CONCLUSIONS
  This is the first study to investigate the direct effects of dopaminergic drugs on reasoning biases. The JTC bias and overconfidence in errors showed a differential pattern of dopaminergic modulation, suggesting that they represent different facets of reasoning abnormalities that interact with each other to produce delusions in susceptible individuals.
authors: *To whom correspondence should be addressed; Martinistrasse 52, 20246 Hamburg, Germany; tel: +49-40-7410-59460, fax: +49-40-7410-59805, e-mail: c.andreou@uke.de.
authors: Christina
authors: C
authors: Andreou
authors: Steffen
authors: S
authors: Moritz
authors: Kristina
authors: K
authors: Veith
authors: Ruth
authors: R
authors: Veckenstedt
authors: Dieter
authors: D
authors: Naber
mesh_terms: D000328:Adult; D003071:Cognition / Q000187:drug effects*; D018592:Cross-Over Studies; D003657:Decision Making / Q000187:drug effects*; D003702:Delusions / Q000523:psychology; D018491:Dopamine Agonists / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006220:Haloperidol / Q000494:pharmacology*; D006801:Humans; D007600:Judgment / Q000187:drug effects*; D007980:Levodopa / Q000494:pharmacology*; D008128:Logic; D008297:Male; D012559:Schizophrenia; D012565:Schizophrenic Psychology; D055815:Young Adult
chemical_list: D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D007980:Levodopa; D006220:Haloperidol
keywords: delusions; jumping to conclusions; liberal acceptance; metacognition; reasoning biases; schizophrenia
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