This research investigates the development of symbolic or representational play in two species of the genus "Pan", bonobos ("Pan paniscus") and chimpanzees ("Pan troglodytes"). The participants varied not only by species, but also as to whether they had become proficient in communicating with humans via a set of arbitrary visual symbols, called…

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 present study explores how suppositions which conflict with accepted beliefs are represented and reasoned about. Two studies test the predictions regarding the nature and developmental changes in children's ability to represent and reason about hypothetical or make-believe suppositions which violate their everyday knowledge and beliefs. In…