Unpacking Number Word Comprehension in Early Childhood

Children recognize number words prior to understanding the exact numbers, but the limits and mechanisms of this comprehension are unclear. One prominent account suggests that the Approximate Number System (ANS) provides the basis for the number word acquisition process such that symbolic number words are mapped onto imprecise numerical representations, whereas an alternative account suggests that the Object Tracking System (OTS) forms the foundation for the process as children first learn to map number words to exact, small quantities in the subitizing range. Recent theoretical proposals and evidence from longitudinal studies suggest that both the ANS and OTS may be involved in the process, however, how the distinct representations from the ANS and OTS are coordinated in real-time remains untested. Here, children (N = 143, M _age = 3.73 yrs) mapped number words to the referred quantities in a two-alternative forced-choice task where trials were designed with varying ratios and sizes of response options. In line with theories that the innate representational systems for both large, imprecise quantities (i.e., the Approximate Number System) and small, exact sets (i.e., the Object Tracking System) support number word acquisition, comprehension was ratio- and size-dependent, consistent with signatures of the two innate numerical representational systems. These findings provide evidence of the proposed real-time coordination of the ANS and the OTS during number word comprehension.