 In the literature on perceptual learning, by contrast, the distinction between perceptual learning and perceptual maturation is often drawn in terms of the role of the environment. On Goldstone’s account of perceptual learning, to count as perceptual learning, perceptual changes must be caused by the environment. It is important to understand why exactly Goldstone thinks that caused by the environment is a crucial feature of the definition. He thinks it is crucial since this criterion distinguishes between perceptual changes that are simply the result of maturation, and perceptual changes that are the result of learning. As Goldstone puts it, “If the changes are not due to environmental inputs, then maturation rather than learning is implicated” (1998: 586). Manfred Fahle puts it similarly by saying that the term maturation “ascribe[s] the main thrust of the changes in a behavior to genetics, not the environment” (2002: xi). For Fahle, this is what distinguishes it from perceptual learning. 