From single to multiple deWcit models of developmental disorders

The emerging etiological model for developmental disorders, like dyslexia, is probabilistic and multifactorial while the prevailing cognitive model has been deterministic and often focused on a single cognitive cause, such as a phonological deWcit as the cause of dyslexia. So there is a potential contradiction in our explanatory frameworks for understanding developmental disorders. This paper attempts to resolve this contradiction by presenting a multiple cognitive deWcit model of developmental disorders. It describes how this model evolved out of our attempts to understand two comorbidities, those between dyslexia and attention deWcit hyperactivity disorder (ADHD) and between dyslexia and speech sound disorder (SSD). © 2006 Elsevier B.V. All rights reserved.