Predictive coding theories of autism suggest that symptoms could result from an atypical learning of expectations. We assessed whether adults with autism could learn expectations in an uncertain context. Twenty-nine neurotypicals and 25 autistic adults participated in an associative learning task. After hearing a tone, participants had to predict the rotation direction of a dot pair, and to report what they perceived. There was a probabilistic association between the tone and the rotation direction. This association could reverse within a block. Both groups were biased by their expectations, as they reported perceiving a rotation consistent with the contingency in a subset of ambiguous trials where the dots did not rotate. Participants made predictions above chance level, but contrary to neurotypicals, autistic participants updated their prior expectation less after a change in contingency. Computational modeling revealed a smaller influence of associative learning on perceptual expectations in the autism group. In an additional task, participants reported how confident they were about their percepts. Both groups expressed confidence in relation to the stimuli, but certainty ratings reflected response times in neurotypical participants only. These findings, showing a more inflexible adjustment of priors in autism, should help refining the predictive coding hypotheses of autism.