Category structure and semantic priming in retarded adolescents

This study was designed to investigate the internal structure of semantic categories in mentally retarded adolescents as reflected in naming times to pictures of common objects. Pictures were presented in pairs that consisted of either categorically related or unrelated items. For related pairs, both the primes (first pictures) and targets (second pictures) varied in rated "typicality" (Rosch, 1975), being either typical or relatively atypical members of their primary superordinate category. An analysis of naming times to targets revealed a semantic-priming effect; targets in related pairs were named faster than those in unrelated pairs. Of major importance was the finding that naming times varied as a function of both prime typicality and target typicality. The data suggest that the semantic categories of retarded persons have an internal structure generally similar to that of the nonretarded persons from whom the typicality ratings were obtained and that even relatively atypical exemplars are functional category members for retarded persons.