Electrophysiological longitudinal evidence for shared number symbol-quantity representations in 5–6-year-old children in only the subitizing range

How number symbols (e.g. Arabic digits) acquire their numerical meaning in early childhood is topic of debate. Whereas it was long assumed that number symbols acquire numerical meaning by associating them directly with early present non-symbolic representations, recent work suggests that this is only the case for small symbols representing quantities in the subitizing range. To investigate this, the present developmental study adopted a mixed longitudinal - cross-sectional design in combination with measurement of performance and the P2p-ERP component in symbolic and non-symbolic number comparison tasks. Complete data was collected from twenty-six 5-6 year-olds in kindergarten and one year later in grade 1, and from young adults. Children and adults showed comparable behavioral numerical distance effects in both subitizing (1-4), and non-subitizing (6-9) ranges in both tasks. Distance effects on P2p amplitude were present in both tasks, and for both numerical ranges in adults, but only for the subitizing range in children. Since P2p amplitude modulations by numerical distance are assumed to reflect access to analog quantity representations, the current findings imply that children only rely on non-symbolic number representations when making quantity comparisons between number symbols within the subitizing range, supporting suggestions that exact non-symbolic – symbolic mapping only underlies the learning of number symbols in the subitizing range, but not beyond.

数字符号（如阿拉伯数字）在儿童早期如何获得其数值意义，这一问题迄今仍存在学术争议。长期以来，学界普遍认为数字符号是通过直接与先天存在的非符号数量表征建立联结来获得数值意义的；但近期研究表明，该机制仅适用于代表感数范围内（1~4）数量的小数字符号。为探究这一学术问题，本项发展心理学研究采用了混合纵向-横断设计，并结合了行为表现测量与符号、非符号数字比较任务中的P2p事件相关电位（P2p-ERP）成分分析。研究共收集了三类样本的完整数据：26名幼儿园阶段的5~6岁儿童、1年后对其进行追踪测试的同批一年级学生，以及青年成年人。在两类任务的感数（1~4）与非感数（6~9）范围内，儿童与成人均表现出相似的行为学数值距离效应。对于P2p振幅的数值距离效应，成人在两类任务的两类数量范围内均有体现；但儿童的该效应仅存在于感数范围中。由于学界普遍认为数值距离对P2p振幅的调制作用反映了个体对类比数量表征的调取过程，本研究结果表明，儿童仅在对感数范围内的数字符号进行数量比较时，才会依赖非符号数量表征。这一发现支持了以下观点：精确的非符号-符号映射仅为感数范围内数字符号学习的认知基础，而不适用于更大范围的数字符号学习。