Modularity and Developmental Disorders

In this chapter, we consider the origin of uneven cognitive profiles in individuals with developmental disorders, including accounts from cognitive, brain, and genetic levels of description. We begin by introducing the main types of developmental disorder. We then discuss what is meant by the idea of modularity and the key issues surrounding it, outlining how modularity has been applied to explain deficits in developmental disorders. We illustrate competing theoretical positions by contrasting two developmental disorders, Williams syndrome (WS) and specific language impairment (SLI). In the first case, we consider cognitive deficits in WS with reference to modularity at a cognitive level and evidence from behavioral studies. In the second case, we consider SLI with reference to modularity at the neural level and evidence from brain imaging studies. We finish by considering the future for modular theories of atypical development, including the implication of recent findings from genetics and from computational modeling.