Namdar Gal, Ganel Tzvi
Department of Psychology, Ben-Gurion University of the Negev, Beer-Sheva, 8410500, Israel.
Psychol Res. 2018 May;82(3):488-495. doi: 10.1007/s00426-016-0837-3. Epub 2017 Jan 20.
Recent literature has established a directional influence of irrelevant numerical magnitude on actions performed toward neutral objects. For example, fingers' aperture during grasping is larger when associated with large compared with small numerical digits. This interaction between symbolic magnitude and visuomotor control has been attributed to the planning stage of the action prior to motor execution. However, this assumption has not been directly tested. In two experiments, we tested whether the effects of numerical magnitude on grasping derive from action planning or from action execution. Participants were asked to grasp an object following a short visual (Experiment 1) or auditory (Experiment 2) presentation of small (1/2) or large (8/9) digits. Grasping was performed under either closed-loop (CL) or open-loop (OL) visuomotor control, for which online vision was prevented during action execution. Digit magnitude affected grip apertures in the CL condition, when online vision was allowed. However, magnitude had no effects on grip aperture in the OL condition. This pattern of results strongly suggests that the processing of numerical magnitude originates from interactions between numerical magnitude and real object size during online motor execution. Unlike previously assumed, the findings also suggest that the effect of magnitude on visuomotor control is not likely to be attributed to the motor planning stage prior to action initiation.
近期文献已证实无关数字大小对针对中性物体所执行动作具有定向影响。例如，与小数字相关联时，抓握过程中手指的张度比与大数字相关联时更大。符号大小与视觉运动控制之间的这种相互作用已归因于动作执行之前的动作规划阶段。然而，这一假设尚未得到直接验证。在两项实验中，我们测试了数字大小对抓握的影响是源于动作规划还是动作执行。参与者在短暂视觉呈现（实验1）或听觉呈现（实验2）小数字（1/2）或大数字（8/9）之后被要求抓握一个物体。抓握在闭环（CL）或开环（OL）视觉运动控制条件下进行，在动作执行过程中这两种条件均阻止在线视觉反馈。当允许在线视觉反馈时，数字大小在CL条件下影响抓握张度。然而，数字大小在OL条件下对抓握张度没有影响。这种结果模式强烈表明，数字大小的处理源于在线运动执行过程中数字大小与真实物体大小之间的相互作用。与之前的假设不同，研究结果还表明，大小对视觉运动控制的影响不太可能归因于动作发起之前的运动规划阶段。
