Perception and Action Lab, Department of Psychology, 190 Dysart Rd, University of Manitoba, Winnipeg, MB R3T-2N2, Canada.
Hum Mov Sci. 2020 Jun;71:102625. doi: 10.1016/j.humov.2020.102625. Epub 2020 May 3.
While much has been learned about the visual pursuit and motor strategies used to intercept a moving object, less research has focused on the coordination of gaze and digit placement when grasping moving stimuli. Participants grasped 2D computer generated square targets that either encouraged placement of the index finger and thumb along the horizontal midline (Control targets) or had narrow "notches" in the top and bottom surfaces of the target, intended to discourage digit placement near the midline (Experimental targets). In Experiment 1, targets remained stationary at the left, middle, or right side of the screen. Gaze and digit placement were biased toward the closest side of non-central targets, and toward the midline of center targets. These locations were shifted rightward when grasping Experimental targets, suggesting participants prioritized visibility of the target. In Experiment 2, participants grasped horizontally translating targets at early, middle, or late stages of travel. Average gaze and digit placement were consistently positioned behind the moving target's horizontal midline when grasping. Gaze was directed farther behind the midline of Experimental targets, suggesting the absence of a flat central grasp location pulled participants' gaze toward the trailing edge. Participants placed their digits at positions closer to the horizontal midline of leftward moving targets, suggesting participants were compensating for the added mechanical constraints associated with grasping targets moving in a direction contralateral to the grasping hand. These results suggest participants minimize the effort associated with reaching to non-central targets by grasping the nearest side when the target is stationary, but grasp the trailing side of moving targets, even if this means placing the digits at locations on the far side of the target, potentially limiting visibility of the target.
虽然人们已经了解了很多关于追踪移动物体和使用运动策略来拦截移动物体的知识，但对于在抓取移动刺激物时眼球运动和手指放置的协调，研究得还比较少。参与者抓取 2D 计算机生成的正方形目标，这些目标要么鼓励食指和拇指放在水平中线（对照目标）上，要么在目标的上表面和下表面有狭窄的“凹口”，旨在阻止手指靠近中线（实验目标）放置。在实验 1 中，目标固定在屏幕的左侧、中间或右侧。当目标不在中心时，眼球运动和手指放置会偏向最近的一侧，而当目标在中心时，会偏向中线。当抓取实验目标时，这些位置会向右移动，这表明参与者优先考虑目标的可见性。在实验 2 中，参与者抓取水平平移的目标，目标在运动的早期、中期或晚期。当抓取时，平均眼球运动和手指放置位置始终位于移动目标的水平中线之后。当抓取实验目标时，眼球被引导到更远的中线后面，这表明没有平坦的中央抓取位置会将参与者的目光拉向目标的拖尾。参与者将手指放置在更靠近左移目标的水平中线的位置，这表明参与者通过在目标静止时抓取最近的一侧来补偿与抓取与抓取手相反方向移动的目标相关的额外机械约束，从而最小化与到达非中心目标相关的努力。这些结果表明，参与者通过在目标静止时抓取最近的一侧来最小化到达非中心目标的努力，但会抓取移动目标的拖尾侧，即使这意味着将手指放置在目标远侧的位置，这可能会限制目标的可见性。
