Person:

Kalra, Priya

Children often make letter reversal errors when first learning to read and write, even for letters whose reversed forms do not appear in normal print. However, the brain basis of such letter reversal in children learning to read is unknown. The present study compared the neuroanatomical correlates (via functional magnetic resonance imaging) and the electrophysiological correlates (via event-related potentials or ERPs) of this phenomenon in children, ages 5–12, relative to young adults. When viewing reversed letters relative to typically oriented letters, adults exhibited widespread occipital, parietal, and temporal lobe activations, including activation in the functionally localized visual word form area (VWFA) in left occipito-temporal cortex. Adults exhibited significantly greater activation than children in all of these regions; children only exhibited such activation in a limited frontal region. Similarly, on the P1 and N170 ERP components, adults exhibited significantly greater differences between typical and reversed letters than children, who failed to exhibit significant differences between typical and reversed letters. These findings indicate that adults distinguish typical and reversed letters in the early stages of specialized brain processing of print, but that children do not recognize this distinction during the early stages of processing. Specialized brain processes responsible for early stages of letter perception that distinguish between typical and reversed letters may develop slowly and remain immature even in older children who no longer produce letter reversals in their writing.

This dissertation attempts to link models from cognitive neuroscience with problems and models from education research as well as to advance our understanding of implicit learning. In addition to a review of the current understanding of implicit learning from psychology and neuroscience, an essay on the potential applications of implicit learning to education and two empirical studies comprise this document. The first study compares implicit learning in adults and children to address the question of developmental invariance in implicit learning. One novel aspect of this study is the use of a battery of implicit learning tasks, as well as comparison explicit learning tasks. Although gross differences were not found between adults and children in the implicit learning tasks, nevertheless first-level item analysis revealed that children and adults may differentially exploit stimulus frequency information to perform the tasks. The second study uses parallel forms of multiple implicit learning tasks to determine the reliability of implicit learning tasks for adult participants. Contrary to the prevailing view of implicit learning, stable individual differences were found. Correlations between individual implicit learning and certain non-cognitive traits (such as conscientiousness) were found, but IQ was not correlated with implicit learning. Finally, the implications of these findings for basic research as well as for the possibility of applying implicit learning to K-12 instruction are discussed.