-Language development in children with Down syndrome is delayed, on average, relative to general cognitive, motor and social development, and there is also evidence for specifi c delays in morphology and syntax, with many adults showing persistent problems in these areas. It appears that the combined use of signed and spoken input can boost early language development signifi cantly, this evidence coming initially from single case-studies, and more recently from larger scale controlled studies. Research with typically developing hearing and deaf children, as well as children with Down syndrome, has demonstrated the importance of establishing joint attention for vocabulary development. Furthermore, studies carried out with children with Down syndrome indicate that reducing attentional demands may be especially important in scaffolding language development in this group. The use of signing strategies which have been found to facilitate language development in deaf children when signing to children with Down syndrome is discussed, as is the need for further research on this topic and on the importance of joint attention for the use of other augmentative and alternative communication systems, such as graphic symbol and picture systems.Keywords -Down syndrome, language, lexical development, signing, augmentative and alternative communication, joint attention
Language and cognitive development in children with Down syndromeIt is now well established that people with Down syndrome typically experience specifi c delays and defi cits in language relative to other cognitive domains, with many adults showing persistent problems in the areas of morphology and syntax (Fowler, 1990; Miller, 1992;Rondal & Comblain, 1996;Tager-Flusberg, 1999). There is, however, much variability between individuals, with some developing to a much higher level of linguistic competence (Rondal, 1995). The profi le of abilities can also change over time in the same individual. Miller (1999) found evidence for several distinct cognitive profi les in children with Down syndrome. The most common pattern was one in which receptive language and nonverbal mental age were in advance of expressive language, but there were smaller groups who showed different patterns, including a substantial group whose expressive language was at the same level as their receptive language and nonverbal ability, and others who showed delays in both receptive and expressive language. The same individuals could show different profi les when tested at different times over a two-year period. Recent work by Paterson (2000; see also Paterson, Brown, Gsödl, Johnson & Karmiloff-Smith, 1999) also indicates that cognitive profi les in both Down syndrome and Williams syndrome change over time, emphasising the importance of developmental processes and the problems that can be encountered when applying an adult neuropsychological model to genetic disorders.
Joint attention and early language developmentOne major infl uence on early language development, and particularly lexical...