Basic level and superordinate level categorization by autistic, mentally retarded, and normal children

Three experiments designed to test autistic children's nonverbal and verbal categorization abilities are reported in this paper. In the first two experiments, 14 autistic children were compared to 14 retarded and 14 normal children matched on verbal mental age. Their ability to categorize pictures from basic level categories and from biological and artifactual superordinate level categories was assessed using a matching-to-sample procedure. The three groups of subjects were similar in their performance. Basic level categorization was easier than more abstract categorization, and for all three groups, prototypicality played a role in categorizing superordinate level concepts; that is, children in all three groups made more errors categorizing peripheral examples. In the third experiment, a subgroup of 7 autistic children showed evidence that their lexicons were well organized and that they appreciated the meaning relationships among words at the superordinate level. These findings suggest that autistic children do not suffer a specific cognitive deficit in the ability to categorize and form abstract concepts, as has been previously suggested in the literature.