Nonsymbolic and symbolic magnitudes processing in children with mathematical difficulties

Abstract

There is a persistent debate in the literature on the mechanisms related to specific deficits in Mathematical Difficulties (MD). The core deficit hypothesis states that children with MD present difficulties to process and manipulate nonsymbolic magnitudes. On the other hand, the access deficit hypothesis proposes that children with MD present intact nonsymbolic magnitude processing abilities, but an impaired capacity to link symbolic numbers to their correspondent analog representations. This master's thesis investigated the performance of children with MD in nonsymbolic and symbolic magnitude processing, and the association of these abilities to math achievement. In the first study, children with MD were compared to typical achievement (TA) peers in nonsymbolic and symbolic magnitude comparison tasks, indexed by reaction time, accuracy, distance effect and Weber fraction. Children with MD presented difficulties in the nonsymbolic but not in the symbolic magnitude processing. Finally, both symbolic and nonsymbolic magnitude processing predicted the math achievement of TA, but not MD children. In the second study, children with MD and TA were compared regarding nonsymbolic magnitude processing and two-digit number processing and the relationship between these abilities and arithmetic and numerical transcoding skills was investigated. Children with MD presented difficulties in nonsymbolic and two-digit number processing, and both abilities were associated to math achievement and numerical transcoding skills. Overall, results of the first and the second studies support the core deficit hypothesis, and reinforce the importance of numerical processing for math achievement