Sheridan Rebecca, van Rooijen Maaike, Giles Oscar, Mushtaq Faisal, Steenbergen Bert, Mon-Williams Mark, Waterman Amanda
School of Psychology, University of Leeds, Leeds, YSW, LS2 9JT, UK.
Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, The Netherlands.
Exp Brain Res. 2017 Oct;235(10):3141-3152. doi: 10.1007/s00221-017-5019-z. Epub 2017 Jul 27.
Mathematics is often conducted with a writing implement. But is there a relationship between numerical processing and sensorimotor 'pen' control? We asked participants to move a stylus so it crossed an unmarked line at a location specified by a symbolic number (1-9), where number colour indicated whether the line ran left-right ('normal') or vice versa ('reversed'). The task could be simplified through the use of a 'mental number line' (MNL). Many modern societies use number lines in mathematical education and the brain's representation of number appears to follow a culturally determined spatial organisation (so better task performance is associated with this culturally normal orientation-the MNL effect). Participants (counter-balanced) completed two consistent blocks of trials, 'normal' and 'reversed', followed by a mixed block where line direction varied randomly. Experiment 1 established that the MNL effect was robust, and showed that the cognitive load associated with reversing the MNL not only affected response selection but also the actual movement execution (indexed by duration) within the mixed trials. Experiment 2 showed that an individual's motor abilities predicted performance in the difficult (mixed) condition but not the easier blocks. These results suggest that numerical processing is not isolated from motor capabilities-a finding with applied consequences.
数学运算通常借助书写工具来进行。但是，数字处理与感觉运动“笔”控制之间存在关联吗？我们要求参与者移动一支触控笔，使其在由一个符号数字（1 - 9）指定的位置穿过一条无标记的线，其中数字的颜色表明这条线是从左到右（“正常”）还是相反方向（“反转”）。通过使用“心理数字线”（MNL），这项任务可以得到简化。许多现代社会在数学教育中使用数字线，并且大脑对数字的表征似乎遵循一种由文化决定的空间组织方式（因此更好的任务表现与这种文化上正常的方向相关——即心理数字线效应）。参与者（经过平衡处理）完成了两个一致的试验块，“正常”和“反转”，随后是一个混合试验块，其中线的方向随机变化。实验1证实了心理数字线效应是稳健的，并且表明与心理数字线反转相关的认知负荷不仅影响反应选择，还影响混合试验中的实际运动执行（以持续时间为指标）。实验2表明，个体的运动能力可以预测在困难（混合）条件下的表现，但不能预测在较容易的试验块中的表现。这些结果表明，数字处理并非与运动能力相互孤立——这一发现具有实际应用意义。
