Predictors of foundational reading competence in speaking and non-speaking children with intellectual disabilities

\Phonological awareness, knowledge of grapheme-phoneme correspondences, working memory, and broader linguistic factors are well-established predictors of the acquisition of foundational reading skills in students with and without intellectual disabilities. However, empirical evidence remains limited regarding the specific factors that contribute to literacy learning difficulties in children with intellectual disabilities who rely on augmentative and alternative communication (AAC). The present study aimed to examine predictors of basic reading abilities in children with intellectual disabilities, both with and without spoken language, using standardized assessments and eye-tracking measures during word decoding tasks. A total of 71 children with mild to moderate intellectual disabilities participated, including 12 children who use AAC. Correlational and regression analyses were conducted to identify significant predictors. Performance in word decoding was significantly predicted by auditory memory, grapheme-phoneme correspondence knowledge, phonological awareness, and first fixation duration on target words within a "text-image choice" paradigm, the latter reflecting mechanisms of visual attention regulation. The variable "spoken language" did not account for additional variance beyond these predictors. The findings are discussed with regard to their implications for the design of evidence-based reading instruction. In particular, phonologically oriented interventions are recommended for children with mild to moderate intellectual disabilities, irrespective of their spoken language abilities.