The relationships among phonological processing, orthographic processing, and lexical development in children with reading disabilities

The purpose of this study was to examine the relationship between phonological and orthographic processing skills in relation to the two lexical acquisition systems (i.e., word-specific knowledge and sub-word orthographic-phonological connections) in children with and without reading disabilities (RD). Performance on measures of phonemic awareness, orthographic processing, and print exposure in 16 fifth- and sixth-grade children with RD was compared to that of three control groups without RD (each with N = 16): a chronological-age matched group of children and two different groups of reading-age-matched children. One reading-age group was matched with the group of children with RD on pseudoword identification skills (considered a proxy for the robustness of subword orthographic-phonological connections in the lexicon); the other was matched on exception-word identification (used to approximate word-specific knowledge in the lexicon). Results were consistent with the hypothesis that children with RD add word-specific entries to their lexicons without a corresponding expansion of subword orthographic-phonological connections. Furthermore, this lexical asymmetry fully accounts for differences in phonemic awareness and orthographic processing skill differences between children with and without RD. Results indicate that phonological and orthographic processes may be less integrated in children with RD.