Date of Award

12-2006

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Psychology

Major Professor

Teresa A. Hutchens, Joel F. Lubar

Committee Members

Debora R. Baldwin, Tara S. Wass

Abstract

Dyslexia research has implicated phonetic dysfunction in the phoneme-grapheme associations which underlie reading skills. Expert readers of normal developmental etiology have required less mental effort, faster processing speed, and reduced focal attention when applying reading subskills. Readers with dysphonia and poorly automatized reading subskills have required more time, mental effort, and attention. Dyslexia automaticity deficit has been attributed to left hemisphere neuro-cortical disruptions of the underlying neurological substrata that support developmental acquisition of reading subskills. Effects of inefficiently automatized phoneme-grapheme skills accumulate over time resulting in poor reading skills that are detrimental to academic achievement.

Using neuropsychological methodology, adults with dysphonetic dyslexia were selected for automaticity investigation via psychometrics and quantitative electroencephalography. Clinical group inclusion criteria included a current Learning Disability (LD) diagnosis in the reading skills domain and dysphonia evidence. LD and non-clinical (NC) adult volunteers were characterized by phonetic ability after administration of selected subtests of Woodcock Johnson, Revised, Achievement Tests, namely, Word Attack, Letter-Word Identification, and Passage Comprehension. Neuropsychological automaticity tasks included Rapid Automatized Naming, Rapid Alternating Stimuli, and Color-Word Stroop. Response time and Stroop-effect data were recorded. Passive electroencephalographic data collection technique allowed access to remnant cortical activity after the performance of automaticity tasks. Active task electroencephalographic data was collected during the performance of Congruent and Incongruent Stroop subtests.

Automaticity in this LD sample was characterized by slower response times and comparable cortical activation to NC group; the LD group required more time, but used similar cortical activation to achieve the same outcome of the NC group. Response time data, related to speed of processing, demonstrated that the LD participants required more time to complete the neuropsychological tasks; however the differences of some response time results disappeared when covaried with age. Electrophysiological data, reflecting cortical activation and mental effort, demonstrated comparable between group activations during both the passive and active recording tasks for left frontal and temporal cortical target locations. Some support was found for the semantic processing interpretation for the Color-Word Stroop.

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