Developmental Changes in the Profiles of Dyscalculia: An Explanation Based on a Double Exact-and-Approximate Number Representation Model

Studies on developmental dyscalculia (DD) have tried to identify a basic numerical deficit that could account for this specific learning disability. The first proposition was that the number magnitude representation of these children was impaired. However, Rousselle and Noël (2007) brought data showing that this was not the case but rather that these children were impaired when processing the magnitude of symbolic numbers only. Since then, incongruent results have been published. In this paper, we will propose a developmental perspective on this issue. We will argue that the first deficit shown in DD regards the building of an exact representation of numerical value, thanks to the learning of symbolic numbers, and that the reduced acuity of the approximate number magnitude system appears only later and is secondary to the first deficit

Is Finger-counting Necessary for the Development of Arithmetic Abilities?

Is finger-counting necessary for the development of arithmetic abilities

How do symbolic and non-symbolic numerical magnitude processing skills relate to individual differences in children\u27s mathematical skills? A review of evidence from brain and behavior

Many studies have tested the association between number magnitude processing and mathematics achievement. However, results appear to be quite different depending on the number format used. When using symbolic numbers (digits), data consistent and robust across studies and populations have been found, with weaker performance associated with weak math achievement and dyscalculia. However, when using non-symbolic format (dots), many conflicting findings are reported. These inconsistencies might be explained by methodological issues. Alternatively, it might be that the processes measured by non-symbolic tasks are not particularly critical for school-relevant mathematics. A few neuroimaging studies have also shown the brain signature of these effects. During numerical magnitude processing, the degree of brain activation (mostly in parietal areas) varies with the children’s degree of math achievement, but the consistency of such relationships for symbolic and non-symbolic processing is unclear. These neurocognitive data provide ground for educational interventions, which seem to have positive effects on children\u27s numerical development in typical and atypical populations

How and when children master the numerical content conveyed by verbal numbers and number gestures ?

Peer reviewe

The role of short-term memory and visuo-spatial skills in numerical magnitude processing: evidence from Turner syndrome

Peer reviewe

The MAORY first-light adaptive optics module for E-ELT

The MAORY adaptive optics module is part of the first light instrumentation suite for the E-ELT. The MAORY project phase B is going to start soon. This paper contains a system-level overview of the current instrument design