The study of cognitive development has been, and still is, faced with two fundamental problems. They are connected, and no satisfactory answer has been found to either. The first problem concerns a terminological distinction and the corresponding semantic contents - it is important to be clear about which characteristics make it possible to distinguish percepts from concepts proper. The second problem, which depends on such distinction, consists in determining when and how, in cognitive development, the turn from perceptual categories into (...) concepts occurs. This paper provides a clear and precise answer to both questions. (shrink)

People are remarkably smart: They use language, possess complex motor skills, make nontrivial inferences, develop and use scientific theories, make laws, and adapt to complex dynamic environments. Much of this knowledge requires concepts and this study focuses on how people acquire concepts. It is argued that conceptual development progresses from simple perceptual grouping to highly abstract scientific concepts. This proposal of conceptual development has four parts. First, it is argued that categories in the world have different structure. Second, there might (...) be different learning systems that evolved to learn categories of differing structures. Third, these systems exhibit differential maturational course, which affects how categories of different structures are learned in the course of development. And finally, an interaction of these components may result in the developmental transition from perceptual groupings to more abstract concepts. This study reviews a large body of empirical evidence supporting this proposal. (shrink)