Introduction

In recent years, several researchers have attempted to apply the adult neuropsychological model to neurodevelopmental disorders. In the adult model, localized brain damage gives rise to a juxtaposed pattern of impaired and intact abilities. When applied to neurodevelopmental disorders, this approach fails to capture the role of development itself in the formation of the final phenotype. An alternative to this common strategy is a neuroconstructivist approach that considers the contribution of the infant start state, the entire developmental trajectory, and underlying cognitive processes to the phenotypic outcome. Results from studies of language and number in infants and toddlers with Williams syndrome and Down syndrome, along with a briefer discussion of face processing, will be presented in support of this position. The application of this approach to other developmental disorders such as autism will also be discussed.

The traditional adult neuropsychological approach to disorder is a static one, in contrast to a neuroconstructivist perspective, which emphasizes the importance of development and of studying early development and not just the endstate in older children and adults. A theoretically driven investigation of the cognitive processes underlying behavior as well as the use of converging measures to describe these processes are crucial aspects of understanding neurodevelopmental disorders from a neoconstructivist approach.

Three developmental disorders, i.e., Williams syndrome, Down syndrome, and autism, will be used to illustrate the developmental neoconstructive approach. The majority of studies to be discussed concern the first two groups.