DEVELOPING AN INTUITIVE UNDERSTANDING OF SUBSTANCE KINDS

Children observe many different behaviors of various substances in everyday life. An effective way to interpret and organize the information they receive in this way is to develop an intuitive theory of substance kinds. In the three studies reported here, by age 3 or 4, children from both middle class and lower-middle class backgrounds seemed to appreciate the homogeneous structure of substances. They seemed to believe that any arbitrary portion of a chunk/pile of a substance is the same kind of substance as the whole chunk/pile. They would generalize a substance-relevant property (e.g., taste, smell when it bums) across portions that shared either a common origin or a common substance label. By contrast, they would generalize an entity-relevant property (e.g., coarseness, can be blown away when it's windy) across portions of similar grain size and portion size. Moreover, discussing the concept of ''tiny, homogeneous pieces'' with 4- and 5-year-olds promoted appropriate inductive inferences about substance-relevant properties across portions. Together, these findings suggest that children' s ideas about substances form a rather coherent belief system. While such a belief system may not qualify as a theory because it may lack an explicit causal mechanism, it nonetheless provides a coherent basis for children to reason about substance kinds. (C) 1994 Academic Press, Inc.