Cognitive modularity and genetic disorders

This study challenges the use of adult neuropsychological models for explai ning developmental disorders of genetic origin. When uneven cognitive profi les are found in childhood or adulthood, it is assumed that such phenotypic outcomes characterize infant starting states, and it has been claimed that modules subserving these abilities start out either intact or impaired. Fi ndings from two experiments with infants with Williams syndrome (a phenotyp e selected to bolster innate modularity claims) indicate a within-syndrome double dissociation: For numerosity judgments, they do well in infancy but poorly in adulthood, whereas for Language, they perform poorly in infancy b ut well in adulthood. The theoretical and clinical implications of these re sults could Lead to a shift in focus for studies of genetic disorders.