Specific motor abilities associated with speech fluency in Down's syndrome.

Eight adult male stutterers with Down's syndrome (DS) were compared with a matched group of fluent speakers with DS on verbal and manual motor production tasks at two levels of complexity. The simpler tasks involved diadochokinetic rate (syllable repetition) and finger tapping; the more complex tasks involved the imitation of sentences and placing pegs in the grooved pegboard. On both verbal and manual tasks, stutterers were faster on the simpler but slower on the more complex tasks than were the fluent speakers. The findings suggest that stutterers with DS have a different motor organization than fluent speakers with DS.