Associations and Dissociations of Dyslexia and Dyscalculia: Cognitive Mechanisms Underlying the Comorbidity of Learning Disorders (COLECA)

• Applicant: Privatdozentin Dr. Kristina Moll
• Subject Area: Developmental and Educational Psychology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563383221

Reading, spelling, and arithmetic are crucial domains of school achievement, and neurodevelopmental learning disorders in written language processing (dyslexia) and arithmetic (dyscalculia) have massive negative impacts on academic and professional perspectives and psychosocial wellbeing. There is high cooccurrence of dyslexia and dyscalculia, but the cognitive mechanisms underlying this comorbidity are not well understood. Theoretical models must explain the high rates of comorbidity as well why the two disorders can dissociate. We aim to specify a multi-deficit model that can explain associations and dissociations of dyslexia and dyscalculia, by investigating the complex interplay of cognitive predictors that are domain-specific (dyslexia: phonological processing; dyscalculia: numerical processing) with domain-general predictors of school achievement (language, working memory, executive functions, processing speed). A particular focus of investigation will be on learning and retrieving orthographic and arithmetic facts, which constitute potential factors of overlap between the disorders. Based on a large and representative sample of about 3200 primary school children we investigate direct and indirect effects of domain-specific and -general predictors on variance in reading, spelling, and arithmetic, with a special focus on their co-variance. We will also compare thoroughly selected subgroups of children with isolated disorders in literacy or arithmetic, comorbid disorder and typical development to investigate differences in cognitive profiles. Fact learning and retrieval skills will be investigated with novel experimental paradigms. We also aim to investigate long-term (18 months) stability of subgroup selection. This project is innovative in explicitly integrating research on dyslexia and dyscalculia, which have mostly been investigated separately. We combine a dimensional investigation of a representative sample with fine-grained investigation of subgroups with isolated and combined learning disorders. The collaboration of two research sites (Munich and Graz) allows recruiting a unique sample of children with typical and atypical development in literacy and arithmetic and to assess their profiles in an unprecedented number of constructs. The data collected in this cutting-edge project constitute a major step forward in understanding the heterogeneity of learning disorders and provide a useful foundation for devising tailored interventions.

• DFG Programme: Research Grants
• International Connection: Austria
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Co-Investigator: Professor Dr. Gerd Schulte-Körne
• Cooperation Partners: Professorin Dr. Karin Landerl; Professor Dr. Stephan Vogel