Predictors of developmental dyslexia in European orthographies with varying complexity

TLDR

Investigated how phoneme awareness, rapid automatized naming, and verbal short‑term/working memory relate to dyslexia diagnosis across orthographic complexity. Assessed general cognitive, phonological, and literacy skills in 1,138 controls and 1,114 dyslexics speaking six languages with varying orthographic complexity. Phoneme deletion and rapid automatized naming emerged as the strongest dyslexia predictors, with logistic‑regression accuracy rising as orthographic complexity increased, showing that complex orthographies amplify these effects and worsen dyslexia symptoms.

Abstract

Background: The relationship between phoneme awareness, rapid automatized naming (RAN), verbal short‐term/working memory (ST/WM) and diagnostic category is investigated in control and dyslexic children, and the extent to which this depends on orthographic complexity. Methods: General cognitive, phonological and literacy skills were tested in 1,138 control and 1,114 dyslexic children speaking six different languages spanning a large range of orthographic complexity (Finnish, Hungarian, German, Dutch, French, English). Results: Phoneme deletion and RAN were strong concurrent predictors of developmental dyslexia, while verbal ST/WM and general verbal abilities played a comparatively minor role. In logistic regression models, more participants were classified correctly when orthography was more complex. The impact of phoneme deletion and RAN‐digits was stronger in complex than in less complex orthographies. Conclusions: Findings are largely consistent with the literature on predictors of dyslexia and literacy skills, while uniquely demonstrating how orthographic complexity exacerbates some symptoms of dyslexia.