Language development in genetic disorders

Abstract

The study of language in developmental disorders is an important endea- vour for several reasons. First, it is essential to identify areas of relative strength and weakness in order to gain a profile of the disorder, so that we may best support and facilitate the development of language and commu- nication skills in these individuals. Second, such research provides an insight into questions about the process of typical language development. For example: to what extent do biological factors influence language devel- opment? Does language learning rely on general cognitive processes, or processes that are specific to language? In this chapter, we focus on the process of language development in two contrasting developmental disor- ders: (i) Williams syndrome and (ii) Down syndrome. We provide an over- view of communicative development in Williams syndrome (a more detailed description of the language profile of individuals with Williams syndrome can be found in Chapter 28), and a description of the develop- mental profile of communicative skills in Down syndrome. We will then discuss what has been learned about typical language development through the study of these disorders, as well as introducing new methodologies and techniques for studying cognitive development. Specifically, we will explain how developmental trajectories can be used to characterize both typical and atypical development as a process, and how population modelling techni- ques can be used to investigate the causal mechanisms of atypical develop- ment and behaviour. We conclude with a discussion of future challenges in the study of developmental disorders, and issues that are as yet unresolved.