 According to the modular view of the mind (Fodor 1983), the basic systems involved in perception are encapsulated from information outside of it, excluding its inputs (see Robbins 2015, for a summary of modularity). It might then seem at first glance that cases of perceptual learning challenge the view that the mind is modular, at least insofar as they involve the modulation of perception through any background theory that the subject has. However, it is important to note that Fodor himself seems to allow for such cases of perceptual learning. While he thinks that perception is synchronically impenetrable, he allows for the possibility of diachronic penetration, that is, cases where “experience and training can affect the accessibility of background theory to perceptual mechanisms” (1984: 39).