Young children's discovery of spatial classification

Around the age of 18 months, children begin to classify objects spatially by kind, placing objects of the same kind close together in space and placing unlike objects apart. This behavior may be symbolic in the sense that children use spatial proximity to represent similarity. We examined the possibility that spatial classification is discovered during play—that the external products of play lead children to use space to represent similarity. Experiment 1 was a longitudinal study of four children's classification behaviors, observed from the age of 16 to 21 months. Results suggest that play with one kind of object to the exclusion of another kind leads to the discovery of spatial classification. Experiment 2 examined how children's tendencies to interact with one category might promote spatial classification of multiple categories. Twenty-four 18-month-old children who did not yet spatially classify objects by kind participated. Children who were given the experience of playing with two kinds of objects in a context that promoted interaction with only one kind were more likely to demonstrate spontaneous spatial classification of multiple kinds in a subsequent test period. Children who played equally with both kinds did not show heightened spontaneous classification. The results further suggest that comparison of different kinds during play is critical to the spontaneous occurrence of spatial classification.