On the spatial foundations of the conceptual system and its enrichment.

A theory of how concept formation begins is presented that accounts for conceptual activity in the first year of life, shows how increasing conceptual complexity comes about, and predicts the order in which new types of information accrue to the conceptual system. In a compromise between nativist and empiricist views, it offers a single domain-general mechanism that redescribes attended spatiotemporal information into an iconic form. The outputs of this mechanism consist of types of spatial information that we know infants attend to in the first months of life. These primitives form the initial basis of concept formation, allow explicit preverbal thought, such as recall, inferences, and simple mental problem solving, and support early language learning. The theory details how spatial concepts become associated with bodily feelings of force and trying. It also explains why concepts of emotions, sensory concepts such as color, and theory of mind concepts are necessarily later acquisitions because they lack contact with spatial descriptions to interpret unstructured internal experiences. Finally, commonalities between the concepts of preverbal infants and nonhuman primates are discussed.

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.

Thought before language.

To learn language infants must develop a conceptual base onto which language can be mapped. Recent research in infant cognitive development shows that at least by 9 months of age infants have developed a conceptual system sufficiently rich to allow language to begin. Evidence for this system is shown by categorization of objects above and beyond their perceptual appearance, problem-solving, long-term recall of events, and inductive inferences. During the next year, early concepts gradually become refined. However, at the time when language takes off they are often still less specific than many words in daily use, accounting for the phenomenon of overextension of word meaning.

Understanding spatial relations: flexible infants, lexical adults.

Concepts of containment, support, and degree of fit were investigated using nonverbal, preferential-looking tasks with 9- to 14-month-old infants and adults who were fluent in either English or Korean. Two contrasts were tested: tight containment vs. loose support (grammaticized as 'in' and 'on' in English by spatial prepositions and 'kkita' and 'nohta' in Korean by spatial verbs) and tight containment vs. loose containment (both grammaticized as 'in' in English but separately as 'kkita' and 'nehta' in Korean). Infants categorized both contrasts, suggesting conceptual readiness for learning such spatial semantics in either language. English-speaking adults categorized tight containment vs. loose support, but not tight vs. loose containment. However, Korean-speaking adults were successful at this latter contrast, which is lexicalized in their language. The adult data suggest that some spatial relations that are salient during the preverbal stage become less salient if language does not systematically encode them.