Arithmetic Fact Retrieval Are There Differences Between Children With Developmental Dyscalculia and Those With Mathematical Difficulties?

When diagnosing children with learning disorders (as per ICD-10), their scholastic performance has to be significantly below the level of intelligence. Although this discrepancy criterion has received much criticism in the field of literacy, few researchers in mathematics have examined it. We used a two (mathematical performance) by two (intelligence) factorial design to analyze the arithmetic fact retrieval of low-performing children in mathematics who met the criterion (developmental dyscalculia) or did not (mathematical difficulties) and of two groups of average-achieving children matched for intelligence. The four groups (each n = 27 third-graders) were matched for their attention span and their literacy skills. Children solved addition verification tasks with numbers up to 10 and 20 under standard and under dual task conditions requiring further working memory capacity to evaluate the potential use of counting strategies. Performance in addition tasks proved to be associated with mathematical achievement especially in the higher number range, whereas dual task performance did not point to the use of counting strategies among low performers in mathematics. No interaction between mathematics and intelligence was identified, which would have confirmed the discrepancy criterion. These results illustrate that stable knowledge of arithmetic facts is essential for mathematical achievement, regardless of whether the discrepancy criterion is met.