Beyond the Approximate Number System: Evidence for spatialization of the Object Tracking System at birth.

Human numerical cognition relies on two core systems: the Approximate Number System (ANS), supporting approximate magnitude estimation, and the Object Tracking System (OTS), enabling precise individuation of up to 3 or 4 items. This study tested 32 healthy, full-term newborns (0-3 days old; 18 females) recruited from a maternity ward serving a socioeconomically and ethnically diverse population. Newborns familiarized with 2 elements (OTS range) preferred 1 element on the left, whereas those familiarized with 4 elements (ANS range) preferred 12 elements on the right. This pattern (η²p = 0.462) indicates that both numerical systems exhibit a shared spatial signature from birth, suggesting that spatial organization is a fundamental property of early numerical cognition.