Why parametric measures are critical for understanding typical and atypical cognitive development.

Children's cognitive abilities improve significantly over childhood and adolescence. We know from behavioral research that core cognitive processes such as working memory and mental attention improve significantly across development. Functional magnetic resonance imaging (fMRI) allows for investigating the typically developing, living brain in action. In the last twenty years we have learned a great deal about brain correlates associated with how adults hold and manipulate information in mind, however, neurocognitive correlates across development remain inconsistent. We present developmental fMRI findings on cognitive processes such as working memory and mental attention and discuss methodological and theoretical issues in the assessment of cognitive limitations in the visual spatial and verbal domains. We also review data from typical and atypical development and emphasize the unique contribution parametric measures can make in understanding neurocognitive correlates of typical and atypical development.