Use of contrastive stress in normal, aphasic, and autistic children.

Studies in child language have shown that contrastive stress appears to be an early developing device to mark the topic-comment distinction, and thus is important for the acquisition of pragmatic knowledge. This study examined the use of contrastive stress by autistic children with mean-length-of-utterance (MLU) scores between 1.9 and 4.1 morphemes. Normal and aphasic subjects at similar MLU levels served as contrast groups. The contrastive stress task required that the subjects verbally assess the counterfactual nature of a presupposition in a yes-no question. Toy manipulation was used to elicit the desired responses in a play situation. Listener judgment served as the basis for analyzing results. Although all subject groups were able to perform the task, differences were seen in the number of correct responses and the patterns of stress misassignment .