Examined whether spatial classification is discovered during play and if external products of play lead children to use space to represent similarity. Found through two experiments--a longitudinal study of four children's classification behaviors, and the examination of play behavior with two types of objects--that comparison of different kinds…

The hypothesis that overall-similarity relations structure both adults' and children's classifications of heterogeneous objects (objects that differ in a variety of ways) was supported in two experiments. When objects varied simultaneously on many dimensions, adults and children constructed classifications that maximized within-category similarity…

Argues that the operating characteristics of perceiving and remembering provide a foundation for progress on detailing the processes through which knowledge is realized in real-time tasks and in detailing the processes of developmental change. Includes three examples to illustrate how forming developmental hypotheses in terms of perceiving and…