Department of Developmental and Social Psychology, University of Padova, Padova, Italy.
Department of General Psychology, University of Padova, Padova, Italy.
Dev Sci. 2019 Nov;22(6):e12801. doi: 10.1111/desc.12801. Epub 2019 Mar 5.
Humans represent numbers on a mental number line with smaller numbers on the left and larger numbers on the right side. A left-to-right oriented spatial-numerical association, (SNA), has been demonstrated in animals and infants. However, the possibility that SNA is learnt by early exposure to caregivers' directional biases is still open. We conducted two experiments: in Experiment 1, we tested whether SNA is present at birth and in Experiment 2, we studied whether it depends on the relative rather than the absolute magnitude of numerousness. Fifty-five-hour-old newborns, once habituated to a number (12), spontaneously associated a smaller number (4) with the left and a larger number (36) with the right side (Experiment 1). SNA in neonates is not absolute but relative. The same number (12) was associated with the left side rather than the right side whenever the previously experienced number was larger (36) rather than smaller (4) (Experiment 2). Control on continuous physical variables showed that the effect is specific of discrete magnitudes. These results constitute strong evidence that in our species SNA originates from pre-linguistic and biological precursors in the brain.
人类在心理数字线上用左侧表示较小的数字，用右侧表示较大的数字。动物和婴儿已经证明存在从左到右的空间-数字关联（SNA）。然而，SNA 是否通过早期接触照顾者的方向偏差而习得的可能性仍然存在。我们进行了两项实验：在实验 1 中，我们测试了 SNA 是否在出生时存在，在实验 2 中，我们研究了它是否取决于数量的相对大小而不是绝对大小。55 小时大的新生儿一旦对数字（12）习惯化，就会自发地将较小的数字（4）与左侧关联，将较大的数字（36）与右侧关联（实验 1）。新生儿的 SNA 不是绝对的，而是相对的。只要先前经历的数字较大（36）而不是较小（4），相同的数字（12）就会与左侧而不是右侧关联（实验 2）。对连续物理变量的控制表明，这种效应是离散数量特有的。这些结果有力地证明，在我们的物种中，SNA 源自大脑中的前语言和生物前体。
