Abstract
Understanding numerical symbols (e.g., the verbal number word ‘six’ or the Arabic digit ‘6’) is fundamental to the development of mathematical knowledge, yet how humans acquire meaningful representations of numerical symbols remains an ongoing theoretical question. In this review, we examine major theoretical accounts of symbolic number learning and consider how these perspectives explain the emergence and development of symbolic numerical knowledge. We focus particularly on the processes through which children establish meaningful connections between numerical symbols and their referents, addressing the longstanding symbol-grounding problem in numerical cognition. By synthesizing perspectives across developmental psychology and cognitive neuroscience, we identify areas of convergence and divergence among existing theoretical accounts and highlight key unresolved questions. Building on this synthesis, we propose the Grounded-to-Abstraction Theory, in which symbolic number knowledge emerges through a reciprocal process whereby small number words are initially grounded in exact quantity representations, and learning these symbols simultaneously scaffolds attention to numerical information. As this system develops, attentional control and approximate magnitude representations support the extension of numerical meaning beyond small quantities, while the emerging verbal number system scaffolds the acquisition of Arabic digits, yielding increasingly abstract and interconnected numerical representations. This framework integrates and extends existing theoretical perspectives and generates testable predictions regarding the behavioural and neural mechanisms underlying symbolic number learning in children. Overall, this review positions symbolic number learning as a dynamic developmental process involving multiple interacting representational systems and provides an integrative theoretical framework for understanding how children develop increasingly sophisticated representations of numerical symbols.