Numerosity perception and fraction processing in children with developmental coordination disorder: Dissociating numerical acuity from inhibitory control

Children with Developmental Coordination Disorder (DCD) often struggle with mathematics. However, the cognitive factors associated with these difficulties are still poorly understood. In particular, it is unclear whether mathematical problems in children with DCD reflect deficits in executive functions or in more domain-specific numerical processes. The present study examined these associations using two tasks that tap into numerical processes and inhibitory executive functions at different levels of mathematical complexity. In the numerosity comparison task, participants compared two arrays of dots and judge which is more numerous. Performance on this task reflects numerical acuity but also inhibition, which is required to suppress task-irrelevant perceptual information such as the size or spacing of dots. In the fraction comparison task, participants compare the magnitudes of two fractions, a task that requires fraction magnitude processing but also inhibiting the natural number reasoning. Participants were 60 children aged between 10 and 14 years, including children with a formal diagnosis of DCD and age-matched typical developing (TD) controls. In the numerosity comparison task, children with DCD showed less precise numerical acuity than TD peers, but were not more susceptible than TD to interference from task-irrelevant cues. In contrast, in the fraction comparison task, children with DCD showed stronger interference from the Natural Number Bias (NNB), suggesting greater difficulty inhibiting earlier acquired natural number principles. Overall, these findings highlight the multidimensional nature of the mathematical difficulties faced by children with DCD and shows that the problems may have different origins, possibly depending on the age of acquisition.