title: The influence of prior expectations on facial expression discrimination in schizophrenia.
abstract: BACKGROUND
  Belief inflexibility is a thinking style observed in patients with schizophrenia, in which patients tend to refute evidence that runs counter to their prior beliefs. This bias has been related to a dominance of prior expectations (prior beliefs) over incoming sensory evidence. In this study we investigated the reliance on prior expectations for the processing of emotional faces in schizophrenia.
  
  
  METHODS
  Eighteen patients with schizophrenia and 18 healthy controls were presented with sequences of emotional (happy, fearful, angry or neutral) faces. Perceptual decisions were biased towards a particular expression by a specific instruction at the start of each sequence, referred to as the context in which stimuli occurred. Participants were required to judge the emotion on each face and the effect of the context on emotion discrimination was investigated.
  
  
  RESULTS
  For threatening emotions (anger and fear), there was a performance cost for facial expressions that were incongruent with, and perceptually close to, the expression named in the instruction. For example, for angry faces, participants in both groups made more errors and reaction times (RTs) were longer when they were asked to look out for fearful faces compared with the other contexts. This bias against sensory evidence that runs counter to prior information was stronger in the patients, evidenced by a group by context interaction in accuracy and RTs for anger and fear respectively.
  
  
  CONCLUSIONS
  Overall, the present data suggest an overdependence on prior expectations for threatening stimuli, reflecting belief inflexibility, in schizophrenia.
authors.affiliation: UCL Institute of Cognitive Neuroscience, London, UK.
authors.forename: G
authors.initials: G
authors.lastname: Barbalat
authors.affiliation: Ecole Normale Supérieure de Lyon, France.
authors.forename: M
authors.initials: M
authors.lastname: Rouault
authors.affiliation: UCL Institute of Cognitive Neuroscience, London, UK.
authors.forename: N
authors.initials: N
authors.lastname: Bazargani
authors.affiliation: Department of Psychiatry, Downing Site, University of Cambridge, Cambridge, UK.
authors.forename: S
authors.initials: S
authors.lastname: Shergill
authors.affiliation: UCL Institute of Cognitive Neuroscience, London, UK.
authors.forename: S-J
authors.initials: SJ
authors.lastname: Blakemore
mesh_terms: D000328:Adult; D004192:Discrimination, Psychological / Q000502:physiology; D004644:Emotions / Q000502:physiology*; D005149:Facial Expression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D012938:Social Perception