Stable individual differences in number discrimination in infancy

Previous studies have shown that as a group 6-month-old infants successfully discriminate numerical changes when the values differ by at least a 1:2 ratio but fail at a 2:3 ratio (e.g. 8 vs. 16 but not 8 vs. 12). However, no studies have yet examined individual differences in number discrimination in infancy. Using a novel numerical change detection paradigm, we present more direct evidence that infants’ numerical perception is ratio-dependent even within the range of discriminable ratios and thus adheres to Weber’s Law. Furthermore, we show that infants’ numerical discrimination at 6 months reliably predicts their numerical discrimination abilities but not visual short-term memory at 9 months. Thus, individual differences in numerical discrimination acuity may be stable within the first year of life and provide important avenues for future longitudinal research exploring the relationship between infant numerical discrimination and later developing math achievement.

既往研究表明，6月龄婴儿群体在数值差异至少为1:2比例时能成功辨别数字变化（如8 vs.16），但在2:3比例时则无法辨别（如8 vs.12）。然而，目前尚无研究探讨婴儿期数字辨别能力的个体差异。通过一种新颖的数字变化检测范式，我们提供了更直接的证据：即使在可辨别比例范围内，婴儿的数字感知仍具有比例依赖性，因此遵循韦伯定律（Weber’s Law）。此外，我们发现6月龄婴儿的数字辨别能力可可靠预测其9月龄时的数字辨别能力，但无法预测同期的视觉短时记忆能力。因此，数字辨别敏锐度的个体差异在生命第一年可能保持稳定，这为未来纵向研究婴儿数字辨别能力与后期数学成就之间的关系提供了重要方向。