Implicit learning in typical development and children with developmental
      disorders

Barnes, Kelly Anne.

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Barnes, Kelly Anne.

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Thesis (Ph.D.)--Georgetown University, 2008.; Includes bibliographical references. Learning is critical for the typical development of linguistic, social, and motor skills. However, little is known about whether learning develops during childhood or is disrupted in developmental disorders. This dissertation examined associative implicit learning, which occurs unintentionally and enables learning about variability and stability in the environment (e.g., when or where something is likely to occur). Chapter I discussed theories of brain and cognitive development that guided and informed this body of work. In Chapter II, we investigated whether younger children, older children, and adults differed in learning of simple and complex sequence structure (a source of variability in past studies). Results indicated that sequence-specific learning was sensitive age but not to sequence structure; it was reduced in younger than older children and adults for both sequence structures. Chapters III and IV addressed the status of two forms of learning, implicit sequence learning and implicit spatial contextual learning, in children with ADHD, children with ASD, and matched controls. Children with ADHD showed reduced learning on the implicit sequence task, but did not differ from controls on the implicit spatial learning task. Therefore, results indicated a selective impairment in implicit sequence learning in children with ADHD. In contrast, learning on the implicit sequence learning and implicit spatial contextual learning tasks did not differ between children with ASD and controls, indicating a general sparing of implicit learning in childhood ASD. Chapter V addressed the neural basis of probabilistic implicit sequence learning in children with ASD and controls using functional Magnetic Resonance Imaging (fMRI). Behaviorally intact general skill learning in childhood ASD was reliant upon the same neural networks as controls, whereas behaviorally intact sequence-specific learning in childhood ASD was reliant upon qualitatively different neural networks than controls. Chapter VI discussed the implications of these findings for models of brain and cognitive development in typical childhood development, childhood ADHD, and childhood ASD. The dissertation ends by suggesting that development can be considered in terms of a three-way interactions between developing systems of learning, executive control, and emotional regulation.