There is overwhelming evidence that children's first words are primarily nouns even across languages. These data are interpreted as evidence of a "Natural Partitions Theory," one that holds that the concepts referred to by nouns are conceptually more basic than those referred to by verbs or prepositions. Analysis of data from…

Comments on the article by Jones and Smith in this issue. Describes a program of research that demonstrates the important influence of perception on the structure of concepts. Proposes that both perceptual and nonperceptual information are important to conceptual structure throughout the continuum of knowledge acquisition and that perception is a…