Communicative, sensorimotor, and language skills of young children with Down syndrome.

The transition from preverbal to verbal communication of retarded and nonretarded children was explored in a prospective, longitudinal study. Mental development was tested at ages 13 months and at 2 and 3 years. At age 2 years, the MA of the retarded subjects matched the MA of the nonretarded at 13 months. Sensorimotor development of the retarded children at 2 and 3 years of age was assessed by the Uzgiris-Hunt scales. Splitting the sample according to whether or not the retarded subjects had reached Sensorimotor Stage 6 at age 3 yielded differential results on concurrent language skills. Pragmatic skills measured at age 2 for the retarded subjects were deficient as compared with such skills assessed at 13 months for the nonretarded subjects. Results seem to support the postulate of a skill-specific homology in the transition from preverbal to verbal communication.