title: Who "jumps to conclusions"? A comprehensive assessment of probabilistic reasoning in psychosis following traumatic brain injury (PFTBI), and comparison with TBI, schizophrenia, and nonclinical controls.
abstract: BACKGROUND
  The "jumping to conclusions" (JTC) bias has received significant attention in the schizophrenia and delusion literature as an important aspect of cognition characterising psychosis. The JTC bias has not been explored in psychosis following traumatic brain injury (PFTBI).
  
  
  METHODS
  JTC was investigated in 10 patients with PFTBI using the beads task (ratios 85:15 and 60:40). Probabilistic predictions, draws-to-decision, self-rated decision confidence, and JTC bias were recorded. Responses from 10 patients with traumatic brain injury (TBI), 23 patients with schizophrenia, and 23 nonclinical controls were compared. Relationships were explored between draws-to-decision and current intelligence quotient, affective state, executive function, delusions (severity and type), and illness chronicity (duration).
  
  
  RESULTS
  Groups were comparable on JTC measures. Delusion severity and type were not related to draws-to-decision for either trial. In the entire sample, executive function (reduced mental flexibility) was significantly related to more draws-to-decision on the 60:40 ratio trial.
  
  
  CONCLUSIONS
  We found no evidence for an elevated JTC bias in patients with PFTBI or TBI alone. The influence of executive dysfunction should be considered by future studies using the beads tasks in patient populations. These findings need to be replicated in larger PFTBI and TBI samples.
authors.affiliation: a Brain and Psychological Sciences Research Centre (BPsyC) , Swinburne University of Technology , Melbourne , VIC , Australia.|b Monash-Alfred Psychiatry Research Centre (MAPrc) , Melbourne , VIC , Australia.|c Health Sciences, RMIT University , Bundoora , VIC , Australia.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Batty
authors.affiliation: c Health Sciences, RMIT University , Bundoora , VIC , Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Francis
authors.affiliation: a Brain and Psychological Sciences Research Centre (BPsyC) , Swinburne University of Technology , Melbourne , VIC , Australia.|b Monash-Alfred Psychiatry Research Centre (MAPrc) , Melbourne , VIC , Australia.
authors.forename: Neil
authors.initials: N
authors.lastname: Thomas
authors.affiliation: d Department of Psychiatry , University of Melbourne , Albert Road Clinic, Melbourne , VIC , Australia.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Hopwood
authors.affiliation: e Monash-Epworth Rehabilitation Research Centre , Epworth Hospital , Richmond , VIC , Australia.
authors.forename: Jennie
authors.initials: J
authors.lastname: Ponsford
authors.affiliation: a Brain and Psychological Sciences Research Centre (BPsyC) , Swinburne University of Technology , Melbourne , VIC , Australia.|b Monash-Alfred Psychiatry Research Centre (MAPrc) , Melbourne , VIC , Australia.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Rossell
mesh_terms: D001930:Brain Injuries / Q000150:complications / Q000523:psychology*; D016022:Case-Control Studies; D003071:Cognition; D003702:Delusions / Q000523:psychology; D056344:Executive Function; D006801:Humans; D008128:Logic; D011618:Psychotic Disorders / Q000209:etiology / Q000523:psychology*; D012559:Schizophrenia; D012565:Schizophrenic Psychology; D013850:Thinking
keywords: Psychosis; jumping to conclusions; reasoning bias; schizophrenia; traumatic brain injury