ABSTRACT
This chapter provides a complete review of all the different sign language programmes for the diverse population of children with impaired cognitive functioning. Instead, the approach adopted to concentrate on findings from studies of children diagnosed with the syndrome autistic disorder. It should be recognised, however, that many of the findings from studies of sign language acquisition in mute, autistic children hold also for other groups of non-speaking, mentally retarded children. The sign language development of these children was compared with the spoken language development of 18 hearing children studied by Nelson. Over the past two decades, a number of studies have been conducted that have examined young deaf children's sign language development. Comparisons of the results from longitudinal studies with those from studies of children's spoken language development have shown that there are many parallels in the language acquisition process across language modalities.
