High-functioning adults with autism and control adults were tested on a perceptual learning task that compared discrimination performance on familiar and novel stimuli. Control adults were better able to discriminate familiar than novel stimuli — the perceptual learning effect. No perceptual learning effect was observed in adults with autism although they discriminated the novel stimuli significantly better than control adults. This enhanced discrimination learning about novel, but not familiar, stimuli in autism is discussed in relation to two current hypotheses of information processing in autism — weak central coherence and reduced attention-switching — and a new third hypothesis, which suggests that features held in common between stimuli are processed poorly and features unique to a stimulus are processed well in autism.