Mathematical Competencies in Students With Intellectual Disability: Correlations With Intelligence, Working Memory, and Years of Schooling.

Although early mathematical competencies are crucial for students with intellectual disability (ID), little is known about their cognitive predictors in this population. This study investigates the relationship between early mathematical competencies and intelligence, working memory (WM), as well as years of schooling. In a cross-sectional design, 76 primary school students were assessed using tests for quantity-number competencies, intelligence, and WM. Correlations and quantile regression analyses were conducted. Fluid intelligence showed a stable positive effect across all achievement levels, whereas visual-spatial WM had a particularly strong effect in lower-performing students. The results suggest that cognitive factors, particularly fluid intelligence and visual-spatial WM, play a central role in the development of mathematical competencies in students with ID.