“Left” and “right” coordinates control our spatial behavior and even influence abstract thoughts. For number concepts, horizontal spatial–numerical associations (SNAs) have been widely documented: we associate few with left and many with right. Importantly, increments are universally coded on the right side even in preverbal humans and nonhuman animals, thus questioning the fundamental role of directional cultural habits, such as reading or finger counting. Here, we propose a biological, nonnumerical mechanism for the origin of SNAs on the basis of asymmetric tuning of animal brains for different spatial frequencies (SFs). The resulting selective visual processing predicts both universal SNAs and their context‐dependence. We support our proposal by analyzing the stimuli used to document SNAs in newborns for their SF content. As predicted, the SFs contained in visual patterns with few versus many elements preferentially engage right versus left brain hemispheres, respectively, thus predicting left‐versus rightward behavioral biases. Our “brain's asymmetric frequency tuning” hypothesis explains the perceptual origin of horizontal SNAs for nonsymbolic visual numerosities and might be extensible to the auditory domain.

中文翻译：

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空间数字关联的生物学基础：大脑的非对称频率调谐

“左”和“右”坐标控制着我们的空间行为，甚至影响抽象思维。对于数字概念，水平空间数字关联 (SNA) 已被广泛记录：我们将很少与左侧相关联，将许多与右侧相关联。重要的是，即使在没有语言的人类和非人类动物中，增量也普遍编码在右侧，从而质疑定向文化习惯的基本作用，例如阅读或手指计数。在这里，我们基于动物大脑对不同空间频率 (SF) 的不对称调谐提出了 SNA 起源的生物学、非数值机制。由此产生的选择性视觉处理可以预测通用 SNA 及其上下文依赖性。我们通过分析用于记录新生儿 SNA 的 SF 内容的刺激来支持我们的提议。正如预测的那样，包含在具有很少元素和元素较多的视觉模式中的 SF 分别优先参与右脑半球和左脑半球，从而预测左右行为偏差。我们的“大脑的非对称频率调谐”假设解释了非符号视觉数量的水平 SNA 的感知起源，并且可能可以扩展到听觉域。