title: Intact priors for gaze direction in adults with high-functioning autism spectrum conditions.
abstract: BACKGROUND
  Autism Spectrum Conditions (ASC) are associated with a range of perceptual atypicalities, including abnormalities in gaze processing. Pellicano and Burr (Trends Cogn Sci 16(10):504-10, 2012) have argued that these atypicalities might be explained within a Bayesian framework, in which perception represents the combination of sensory information with prior knowledge. They propose that the Bayesian priors of individuals with ASC might be attenuated, such that their perception is less reliant on prior knowledge than neurotypical individuals. An important tenet of Bayesian decision theory is that increased uncertainty about incoming sensory information will lead to a greater influence of the prior on perception. Consistent with this, Mareschal et al. (Curr Biol 23(8):717-21, 2013) showed that when noise is added to the eyes of a face (increasing uncertainty about gaze direction), gaze is more likely to be perceived as direct.
  
  
  METHODS
  We adopted the same paradigm as Mareschal et al. to determine whether the influence of a prior on gaze perception is reduced in neurotypical participants with high numbers of autistic traits (experiment 1) and in individuals with a clinical diagnosis of ASC (experiment 2). Participants were presented with synthetic faces and asked to make a judgement about the relative gaze directions of the faces. Uncertainty about gaze direction was manipulated by adding noise to the eyes of a face.
  
  
  RESULTS
  Consistent with previous work, in both experiment 1 and experiment 2, participants showed a bias towards perceiving gaze as direct under conditions of uncertainty. However, there was no evidence that the magnitude of this bias was reduced either in the ASC group or in neurotypical controls with a high number of autistic traits.
  
  
  CONCLUSIONS
  Our findings challenge the attenuated priors theory of perception in ASC (Trends Cogn Sci 16(10):504-10, 2012) and related proposals (Trends Cogn Sci 17(1):1, 2013, Front Hum Neurosci 8:302, 2014), and suggest priors for gaze direction are intact in high-functioning ASC.
authors.affiliation: Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, UK.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Pell
authors.affiliation: School of Biological and Chemical Sciences, Psychology Department, Queen Mary University of London, London, UK.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mareschal
authors.affiliation: Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Calder
authors.affiliation: Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, UK ; School of Psychology, Cardiff University, Cardiff, UK.
authors.forename: Elisabeth A H
authors.initials: EA
authors.lastname: von dem Hagen
authors.affiliation: School of Psychology, UNSW Australia, Sydney, NSW Australia.
authors.forename: Colin W G
authors.initials: CW
authors.lastname: Clifford
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Baron-Cohen
authors.affiliation: Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, UK ; MRC Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge, CB2 7EF UK.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Ewbank
mesh_terms: D000328:Adult; D000067877:Autism Spectrum Disorder / Q000503:physiopathology*; D001499:Bayes Theorem; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation; D014796:Visual Perception; D055815:Young Adult
keywords: Autism; Autistic traits; Bayesian priors; Gaze perception; Uncertainty