On the origins of the conceptual system.

Contrary to the conventional view of infancy as a sensorimotor period without conceptual thought, research over the past 20 years has shown that preverbal infants are capable of at least 3 conceptual functions: forming concepts with which to interpret the world, recall of the past, and engaging in conceptual generalization. Research is described indicating that the 1st concepts tend to be global in scope, such as animal or container, and that the course of conceptual development in the first 2 years is largely one of differentiating global concepts into more detailed concepts, such as dog or cup. A theory of how the 1st global concepts are formed from spatial information is briefly presented, including (a) a mechanism that redescribes spatial information into simpler but accessible form and (b) the primitives it uses for this purpose. Finally, the way concepts become more complex by means of language and analogical extension to nonspatial information is discussed.