Children's conception of object, as revealed by their categorizations.

Six- to 11-year-old children were asked to sort objects in a construction set, to examine what types of objects they group together when performing a classification task. Half of the objects were simple pieces, and the other half were constructions made from those pieces. The results showed that these two types of objects are not clearly differentiated by children until relatively late: age 8 years in the first experiment and age 10 or 11 in the second. Children based their sorting on either perceptual or functional equivalency relations (logical sorting) or on suitability relations between objects of different levels (schemas).