Adults with autism overestimate the volatility of the sensory environment.

Abstract

Insistence on sameness and intolerance of change are part of the diagnostic criteria for Autism Spectrum Disorder (ASD) but there is little research addressing how people with ASD represent and respond to environmental change. Here, we find that behavioural and pupillometric measurements show adults with ASD are less surprised than neurotypical adults when expectations are violated, with reduced surprise predicting greater symptom severity. A hierarchical Bayesian model of learning suggests that in ASD a tendency to over-learn about volatility in the face of environmental change drives a corresponding reduction in learning about probabilistically aberrant events – putatively rendering them less surprising. Participant-specific modelled estimates of surprise about environmental conditions are linked to pupil size in the ASD group, suggesting heightened phasic noradrenergic responsivity in line with neural gain impairments. This study offers novel insight into the behavioural, algorithmic and physiological mechanisms that underlie responses to environmental volatility in ASD.