Differential Impacts of Morphology-Focused and Phonology-Focused Interventions on Students with Dyslexia: Evidence from Latent Regression Analysis

Educational interventions for dyslexic students typically focus on phonological skills, yet not all students have phonological deficits or benefit from such approaches. We compared a morphology-focused versus a phonology-focused intervention for fourth graders with dyslexia, accounting for their baseline phonological awareness levels. Over 16 weeks, students received either systematic morphemic pattern instruction or phonology-focused instruction. Using multilevel difference-in-difference modeling, we analyzed pre- and post-test results in decoding, vocabulary, and spelling. The morphology group showed comparable gains in decoding accuracy and spelling to the phonology group across all baseline phonological awareness levels, while achieving significantly higher vocabulary improvements. Notably, students with higher phonological awareness made greater gains across all skills in the morphology condition compared to the phonology condition. This study provides first-time evidence that dyslexic students respond differently to these interventions based on their phonological awareness levels, suggesting the benefit of morphology-focused instruction, particularly for those with stronger phonological skills.