Our goal is to investigate interactions between preverbal numerical abilities and more elaborate numerical capacities, as well as
the causality of these relationships during the development. More specifically, we are studying the potential impact of the
acquisition of numerical symbols (counting words and Arabic numbers) on the number sense indexed by the sensitivity in numerosity
discrimination. By comparing performance of controls and performance of participants who presented a retardation in the access to the
numerical symbols (blind or deaf people), we will be able to assess the extent to which the knowledge about symbolic number is
crucial in the refinement of preverbal numerical abilities.