This article reviews two aspects of human learning: (1) people draw inferences that appear to rely on hierarchical conceptual representations; (2) some categories are much easier to learn than others given the same number of exemplars, and some categories remain difficult despite extensive training. Both of these results are difficult to reconcile…

Ambridge's proposal cannot account for the most basic observations about phonological patterns in human languages. Outside of the earliest stages of phonological production by toddlers, the phonological systems of speakers/learners exhibit internal behaviours that point to the representation and processing of inter-related units ranging in size…