Previous investigations have uncovered a strong visual bias toward the index finger when reaching and grasping stationary or horizontally moving targets. The present research sought to explore whether the index finger or thumb would serve as a significant focus for gaze in tasks involving vertically translating targets. Participants executed right-handed reach-to-grasp movements towards upward or downward moving 2-D targets on a computer screen. When the target first appeared, participants made anticipatory fixations in the direction of the eventual movement path (i.e. well above upwardly moving targets or well below downwardly moving targets) and upon movement onset, fixations shifted toward the leading edge of the target. For upward moving targets, fixations remained toward the leading edge upon reach onset, whereas for downward moving targets, fixations shifted toward the centre of the target. The same central fixation location was observed at the time of grasp for all targets. Furthermore, for downwardly moving targets, the placement of the thumb appears to have influenced fixation location in conjunction with, not replacement of, the influence of the index finger. These findings are indicative of the increasingly relevant role of the thumb in mediating reaching and grasping downwardly moving targets.

中文翻译：

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达到和掌握垂直移动目标时的眼手协调。

先前的研究发现，在到达并抓住静止或水平移动的目标时，食指会产生强烈的视觉偏见。本研究试图探索食指或拇指是否会成为涉及垂直平移目标的任务中凝视的重要焦点。参与者在计算机屏幕上向着向上或向下移动的2-D目标执行了惯用右手的伸手可及的动作。当目标首次出现时，参与者会沿最终移动路径的方向（即，远高于向上移动的目标或远低于向下移动的目标）进行预期的注视，并且在开始运动时，注视移向目标的前缘。对于向上移动的目标，在到达目标位置时注视保持在前缘，而对于向下移动的目标，注视转向目标的中心。抓住所有目标时，观察到相同的中央固定位置。此外，对于向下移动的目标，拇指的放置似乎与食指的影响结合在一起而不是代替了影响固定位置。这些发现表明拇指在调解到达和抓住向下移动的目标中的作用越来越重要。