Understanding the role of oral vocabulary in reading comprehension difficulties

This thesis explores specific reading comprehension difficulties with a focus on the role of oral vocabulary. The first study illustrates the complexities associated with diagnosing reading comprehension difficulties by comparing two widely used assessments of reading comprehension. The second study explores the vocabulary, irregular word reading and oral language skills of a sample of children with poor reading comprehension. The third study presents the results of a randomized controlled trial looking at the effects of an oral vocabulary training program for poor comprehenders. The fourth study presents data from the same children as a repeated measures intervention study with multiple baselines, allowing an exploration of the results of the training program at an individual level. This thesis extends the knowledge of the field by demonstrating that there is variability in the vocabulary skills of poor comprehenders at the individual level, and that poor comprehenders who do not have vocabulary difficulties nonetheless perform poorly on tasks of oral language above the word level. In addition, oral vocabulary training is demonstrated to be successful in improving reading comprehension skills for poor comprehenders with vocabulary deficits, implying a direct causal role for poor oral vocabulary skills in reading comprehension difficulties.