Abstract

This dissertation discusses the effects of dyslexia on reading behavior and cognition. It does so by first outlining the overall incidence of dyslexia, providing current definitions, giving a history of scientific inquiry and discussing relevant contemporary research. Thirteen different analyses are then discussed (ten a priori and three post-hoc). Individuals with dyslexia were found to have increased fixation duration, first run dwell time, total dwell time, and refixation probability. The dyslexia group was also highly sensitive to lexical predictability. Within the reading network, the BOLD response was depressed in dyslexia during reading in the following regions: the left medial and inferior temporal gyrus, the left temporal pole, the right cerebellum, right occipital gyrus and the right parahippocampal gyrus. A second regions of interest analysis in the reading network revealed dyslexia was associated with a depressed BOLD response to lexical predictability in the following regions: left supplementary motor area, posterior middle frontal gyrus, and the left temporal pole. A regions of interest analysis in the oculomotor network revealed a depressed BOLD response in the following regions during reading: the left parietal eye fields and the cerebellum. One oculomotor region had a depressed BOLD response to lexical predictability due to dyslexia: the left frontal eye fields. This sensitivity to lexical predictability and depression in the BOLD response is suggestive of reduced input into higher cortical areas. Future study should be focused on finding the common origin of this bottom-up deficit.

Degree

PhD

College and Department

Family, Home, and Social Sciences; Psychology

Rights

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