Individual Differences: A Dose-Response Analysis of Associations Between Phonological Processing and Reading in Students With Reading Disabilities

• In Event: Reconceptualizing Individual Differences in Reading

Abstract

Early acquisition of accurate and automatic word reading skills is critical to reading fluency and reading comprehension achievement. Phonological processing skills have been recognized to play a causal role in word reading achievement and to be a primary cause of reading disabilities. Given the significant heritable contribution to phonological processing, population variability has frequently been attributed to factors internal to the individual. In beginning readers at-risk for later reading difficulties, however, the contribution of phonological processing to reading achievement has been found to be significantly diminished by early and focused instruction. This finding gives rise to questions concerning the primacy of internal versus environmental factors contributing to the phonological core deficit in students with reading disabilities; an instantiation of the “environmental opportunity” hypothesis versus the “cognitive efficiency” hypothesis.
In the current study, we explored the relationships of phonological processing to word- and text-reading outcomes as a function of the dosage of an intense decoding-focused intervention. We reasoned that this examination could provide a window into the stability versus malleability of the influence of phonological processing skills on reading achievement in students with reading disabilities.
Participants met criteria for a reading disability if standard scores on a word reading test were at or below the 25th percentile and/or scores on a reading-fluency test were at or below the 16th percentile. Participants consisted of 150 students with reading disabilities in grades 1 through 11. Analyses will be presented examining the unique contribution of phonological processing skills to word recognition, text-reading fluency, and reading comprehension following each of 3 phases of the intervention. As expected, the strength of the associations between initial phonological processing skills and reading outcomes diminished across phases of the intervention. Unexpected was the low-dose at which phonological processing skills did not contribute unique variance to reading outcomes.
The results are discussed within two important contexts. First, how individual differences in skills with large heritable components are seemingly quite malleable across increasing doses of an intervention. Second, we consider that the field of reading disabilities has been better at delineating the proximal (and internal) causes of reading difficulties, but might benefit most going forward from a focus on environmental or more distal factors. That is, environmental opportunities have a greater impact on cognitive efficiency in students with reading disabilities than previously thought. There is an increasing tendency for researchers to examine risk-factors for reading disabilities in young children from a broader ecological perspective; we suggest this approach toward understanding and remediating achievement for older students with reading disabilities could be most beneficial.

Authors

• Jamie L Metsala, Mt. Saint Vincent University

• Margaret David, Mt. Saint Vincent University