Linguistic and cognitive ability of adults with Down syndrome and mental retardation of unknown etiology.

The linguistic and cognitive abilities of adults with Down syndrome were compared to those of adults with mental retardation of unknown etiology matched for mental and chronological age. Linguistic data consisted of verbal responses to an elicitation procedure that tested for forty-three different linguistic constructions. Cognitive tests measured simultaneous, successive, auditory, and visual processing. The adults with Down syndrome exhibited significantly poorer linguistic ability than the adults with mental retardation of unknown etiology. Though the two groups exhibited different cognitive profiles, differences in cognitive abilities could not account for the difference in linguistic ability.