Danion Frederic R, Mathew James, Gouirand Niels, Brenner Eli
Aix Marseille Université, CNRS, Institut de Neurosciences de la Timone UMR 7289, Marseille, France.
Aix Marseille Université, CNRS, Institut de Neurosciences de la Timone UMR 7289, Marseille, France.
Cortex. 2021 Jan;134:30-42. doi: 10.1016/j.cortex.2020.10.001. Epub 2020 Oct 17.
When tracking targets moving in various directions with one's eyes, horizontal components of pursuit are more precise than vertical ones. Is this because horizontal target motion is predicted better or because horizontal movements of the eyes are controlled more precisely? When tracking a visual target with the hand, the eyes also track the target. We investigated whether the directional asymmetries that have been found during isolated eye movements are also present during such manual tracking, and if so, whether individual participants' asymmetry in eye movements is accompanied by a similar asymmetry in hand movements. We examined the data of 62 participants who used a joystick to track a visual target with a cursor. The target followed a smooth but unpredictable trajectory in two dimensions. Both the mean gaze-target distance and the mean cursor-target distance were about 20% larger in the vertical direction than in the horizontal direction. Gaze and cursor both followed the target with a slightly longer delay in the vertical than in the horizontal direction, irrespective of the target's trajectory. The delays of gaze and cursor were correlated, as were their errors in tracking the target. Gaze clearly followed the target rather than the cursor, so the asymmetry in both eye and hand movements presumably results from better predictions of the target's horizontal than of its vertical motion. Altogether this study speaks for the presence of anisotropic predictive processes that are shared across effectors.
当用眼睛追踪向各个方向移动的目标时，追踪的水平分量比垂直分量更精确。这是因为水平目标运动的预测更好，还是因为眼睛的水平运动控制得更精确呢？在用手追踪视觉目标时，眼睛也会追踪该目标。我们研究了在孤立的眼球运动中发现的方向不对称性在这种手动追踪过程中是否也存在，如果存在，个体参与者眼球运动的不对称性是否伴随着手部运动的类似不对称性。我们检查了62名使用操纵杆用光标追踪视觉目标的参与者的数据。目标在二维空间中遵循平滑但不可预测的轨迹。垂直方向上的平均注视目标距离和平均光标目标距离都比水平方向大约大20%。无论目标轨迹如何，注视和光标在垂直方向上跟随目标的延迟都比水平方向略长。注视和光标的延迟是相关的，它们追踪目标的误差也是相关的。注视明显跟随目标而不是光标，所以眼球和手部运动的不对称性大概是由于对目标水平运动的预测比对其垂直运动的预测更好。总的来说，这项研究表明存在跨效应器共享的各向异性预测过程。
