Numerical abilities in children with congenital hemiplegia: an investigation of the role of finger use in number processing.

In this study, we assessed basic and more complex non-symbolic and symbolic numerical task abilities in children with hemiplegia and obtained a detailed picture of their strengths and weaknesses in the numerical domain. Those children, who experience difficulties in finger gnosia and spontaneous use of fingers in counting, exhibit difficulties in finger pattern recognition and symbolic numerical tasks. However, their non-symbolic numerical abilities and arithmetic skills are preserved. These original results are discussed in light of the "manumerical cognition" hypothesis, which postulates that the use of fingers in numerical activities during childhood shapes our comprehension of numbers.