title: Jumping to perceptions and to conclusions: specificity to hallucinations and delusions.
abstract: BACKGROUND
  There is evidence that people with psychosis display a "jump-to-conclusions" (JTC) reasoning style, and that this bias may be specific to delusions. A "jump-to-perceptions" (JTP) cognitive bias has also been found and is typically linked to hallucinations. However, there is some evidence for an association between JTP and delusions, and its specificity to hallucinations remains unclear. It has been suggested that these biases are related and products of shared cognitive processes.
  
  
  METHODS
  This study examined the symptom specificity of JTC and JTP, and the relationship between them, in a sample of 98 individuals with delusions divided into 'hallucinators' (n=51) and 'non-hallucinators' (n=47). Biases were assessed using the beads task and visual and auditory perceptual tasks.
  
  
  RESULTS
  As predicted, both groups demonstrated a JTC bias, but the 'hallucinators' showed a more pronounced JTP style in both modalities. The presence of JTC and JTP biases did not co-occur: making a decision on the beads task after two or fewer draws was not related to visual JTP, and was associated with a less marked JTP bias in the auditory perceptual task. No differences were found in JTP or JTC between participants with and without a schizophrenia diagnosis. JTP, but not JTC, was associated with the presence of hallucinations.
  
  
  CONCLUSIONS
  These findings suggest that the JTC and JTP biases show specificity to delusions and hallucinations, respectively, and not to diagnosis. There was no evidence that they are the product of shared cognitive processes, further supporting their specificity.
authors.affiliation: Institute of Psychiatry, King's College London, Department of Psychology, London, UK.
authors.forename: Eleonore
authors.initials: E
authors.lastname: Bristow
authors.affiliation: University College London, Sub-department of Clinical Health Psychology, London, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Tabraham
authors.affiliation: Institute of Psychiatry, King's College London, Department of Psychology, London, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Smedley
authors.affiliation: Institute of Psychiatry, King's College London, Department of Psychology, London, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ward
authors.affiliation: Institute of Psychiatry, King's College London, Department of Psychology, London, UK; National Institute for Health Research (NIHR) Biomedical Research Centre for Mental Health at South London and Maudsley NHS Foundation Trust, London, UK. Electronic address: emmanuelle.peters@kcl.ac.uk.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Peters
mesh_terms: D000328:Adult; D001307:Auditory Perception; D003210:Concept Formation; D003657:Decision Making; D003702:Delusions / Q000209:etiology / Q000523:psychology*; D005260:Female; D006212:Hallucinations / Q000209:etiology / Q000523:psychology*; D006801:Humans; D008297:Male; D010465:Perception; D011569:Psychiatric Status Rating Scales; D011581:Psychological Tests; D012559:Schizophrenia / Q000150:complications; D012565:Schizophrenic Psychology; D014796:Visual Perception
keywords: Cognitive biases; Cognitive models of psychosis; Delusions; Hallucinations; Schizophrenia; “Jump-to-conclusions”; “Jump-to-perceptions”