Comprehension of syntactically indicated sequence by Down's syndrome and other mentally retarded adults

The ability to comprehend syntactically ordered sequence by Down's syndrome adults and adults with mental retardation of no specific aetiology was studied. Both samples exhibited patterns of comprehension that resembled those of children who are not mentally retarded. However, the Down's syndrome individuals had significantly more difficulty when sequence was indicated by syntax with no supporting extralinguistic context. The Down's syndrome adults appeared to be arrested at an earlier stage of development than the other mentally retarded adults.