Intact priors for gaze direction in autism spectrum conditions.

Autism Spectrum Conditions (ASC) are characterized by a range of perceptual atypicalities, including abnormalities in gaze processing. Pellicano and Burr (2012) recently proposed that perceptual atypicalities might be a consequence of attenuated priors in ASC (i.e. reduced influence of prior knowledge on the perception of sensory information). Evidence from neurotypical populations indicates that under conditions of uncertainty (created by adding noise to the eyes of face stimuli), gaze is more likely to be perceived as direct (Mareschal et al., 2013), suggesting that humans have a prior expectation that other people's gaze is directed toward them. Here we adopted the same paradigm to address two questions: 1) Is the influence of priors on gaze perception reduced as a function of autistic traits within a neurotypical population (Experiment 1)? 2) Do individuals with diagnosis of ASC show evidence for reduced influence of gaze priors (Experiment 2)? Each experiment began with a staircase procedure designed to tailor the noise contrast required for each participant to perform a left/right gaze discrimination at 80% correct. Participants were then required to judge the relative gaze directions of two faces when noise was added to the eyes of one face only. In Experiment 1, participants showed a significant bias towards perceiving uncertain gaze as direct, however this bias was not related to increasing autistic traits. In Experiment 2, individuals with ASC showed a robust direct gaze prior comparable to that of IQ matched controls. Given that noise-thresholds did not differ across groups, this finding is unlikely to reflect a combination of attenuated priors and increased sensory noise in ASC. These results pose a challenge to the hypoprior Bayesian model of ASC and suggest that if ASC is characterized by atypicalities in the use of prior information this is not reflected in their performance on a gaze task. Meeting abstract presented at VSS 2015.This research was supported by the UK Medical Research Council under project code MC-A060-5PQ50 (Andrew J. Calder). IM was supported by a Leverhulme Trust Project Grant. CC was supported by an Australian Research Council Future Fellowship. SBC was supported by the MRC, the Wellcome Trust and the Autism Research Trust during the period of this work. The research was also supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care East of England at Cambridgeshire and Peterborough NHS Foundation Trust