Neurocognitive start-up tools for symbolic number representations

This chapter reviews the features of two preverbal systems for numerical quantification, the approximate number system (ANS) and the object tracking system (OTS). This chapter also critically assesses their role in cultural learning of symbolic numbers. The most important defining feature of the ANS is that it represents number in an approximate and compressed fashion, in such a way that two sets can be discriminated only if they differ by a given numerical ratio. The OTS is a mechanism by which objects are represented as distinct individuals that can be tracked through time and space. This core system for representing objects centers on the spatio-temporal principles of continuity and contact. One of the defining properties of this system is that it is limited in capacity to three to four individuals at a time. Event-related potential (ERP) source reconstruction was not performed in this study, and this does not allow any conclusions on anatomical dissociation between the ANS and the OTS. In sum, although somewhat inconsistently across studies, the OTS seems to be associated with regions of the posterior parietal and occipital cortices that do not seem to overlap with regions involved in the ANS. The electrophysiological signatures of the two systems also appear to be distinct. © 2011 Elsevier Inc. All rights reserved.