Mariette: A screening test for reading errors in primary school.

Dyslexia is a multifaceted condition with diverse manifestations, yet assessment tools too often target limited subtypes, creating diagnostic gaps. This study examines the progression of dyslexia-related reading errors across primary school in typically developing readers, using the Mariette, a French nonsense-text reading screener. Analysis of 812 French children (grades 1-5) revealed systematic decreases in error rates with age, following distinct developmental trajectories. Regularizations of irregular words, misapplication of contextual rules and misreading of digraphs predominated in early grades, while voicing errors nearly disappeared by Grade 2. Clinical testing of the Mariette with 18 struggling readers identified specific reading errors overlooked by standard dyslexia assessments. These findings demonstrate the value of precise error analysis for understanding developmental reading patterns and tailoring targeted educational interventions. By comparing typical and clinical populations, this research advances our understanding of dyslexia's cognitive mechanisms while advocating for more comprehensive diagnostic approaches.