SEPARATING THE SHEEP FROM THE GOATS - DIFFERENTIATING GLOBAL CATEGORIES

The nature of the conceptual categories that children have developed in the second year was studied in a series of experiments using an object-manipulation task. In the first two experiments, it was shown that by 18 months children have developed global conceptual categories of animals and vehicles without yet clearly differentiating basic-level categories within these domains. The basic-level categories were tested by using a series of contrasts: a low degree of contrast was provided by presenting the children with dogs versus horses and with cars versus trucks. A moderate degree of contrast consisted of dogs versus rabbits and cars versus motorcycles. A high degree of contrast consisted of dogs versus fish (or birds) and cars versus airplanes. A domain-level contrast of animals versus vehicles was included as well. From 18 to 30 months the children tended to respond categorically only on the global domain-level contrast and on the high-contrast basic-level distinctions. Not until 30 months did the children consistently differentiate the low and moderate basic-level contrasts. Experiment 3 replicated the finding of global animal and vehicle categories, using the widest possible range of exemplars. Experiment 4 extended the study of global categorization to the domains of plants, furniture, kitchen utensils, tools, and musical instruments. Global categorization was found for plants, furniture, and kitchen utensils, but not for tools and musical instruments. Experiment 5 found little evidence for basic-level categorization of plants, and only suggestive evidence for basic-level categorization in the domains of furniture and utensils. The data demonstrate the presence of a number of global conceptual categories from an early age, and suggest that at least in some domains (animals, vehicles, and plants) such categories develop before true basic-level distinctions are made. © 1991.