The reciprocal relationship between oral language and reading skills in children with Down syndrome

This thesis explored the interaction between oral language and reading skills in children with Down syndrome. Study 1 looked at the longitudinal relationship between reading accuracy, reading comprehension and oral language across three time-points. Study 2 taught new spoken words with or without the orthographic form present and Study 3 examined the effect of phonological pre-training on orthographic learning. In all three studies, typically developing children matched for reading accuracy also participated.
The effect of phonological and non-phonological oral language skills on reading accuracy was examined in Studies 1 and 3. In Study 1, phoneme awareness and vocabulary were evaluated as predictors of reading accuracy. Neither were longitudinal predictors in either group due to the strength of the autoregressor. However, vocabulary was a concurrent predictor for the children with Down syndrome. In Study 3, children with Down syndrome showed poorer orthographic learning than typically developing children. However when equated for decoding skill, the level of orthographic learning and the benefit from phonological pre-training were equivalent in the two groups.
The proposed benefit of learning to read on oral language development was tested in Studies 1 and 2. In Study 1, reading accuracy had a moderate effect on vocabulary development for children with Down syndrome and typically developing children. In Study 2, children with Down syndrome and typically developing children showed similar levels of phonological learning, which was facilitated by orthographic support to the same extent.
The relative contribution of reading accuracy and oral language to reading comprehension was evaluated in Study 1. Reading accuracy predicted concurrent reading comprehension for the children with Down syndrome and typically developing children, whereas oral language did not. However, only oral language was a longitudinal predictor in the children with Down syndrome. Theoretical and practical implications of the findings from all three studies are considered.