Autism is well known for the way it affects how a person interacts and communicates with others. But autism can affect behavior in other important and debilitating ways, such as in an intense desire for sameness and in sensory systems that work too well or not well enough. Researchers have largely overlooked the latter "sensory symptoms," but their prominence in forthcoming diagnostic criteria calls for systematic investigation. In this article, I review existing theoretical accounts of autism and provide an overview of a new theoretical account that proposes using Bayesian methods to identify the nature of the (altered) computations involved in autistic sensation and perception. Specifically, the account suggests that sensory symptoms may be due to fewer prior constraints or attenuated "priors." The possibility that autistic people perceive the world as it really is rather than as imbued by prior experiences may explain the range and idiosyncrasy of their sensory sensitivities and their difficulties dealing with new experiences. © 2013 The Society for Research in Child Development.