Eloka Owino, Franz Volker H
Department of Psychology, Justus-Liebig-University Giessen, Germany.
Vision Res. 2011 Apr 22;51(8):925-31. doi: 10.1016/j.visres.2011.02.002. Epub 2011 Feb 12.
Little is known of how visual coding of the shape of an object affects grasping movements. We addressed this issue by investigating the influence of shape perturbations on grasping. Twenty-six participants grasped a disc or a bar that were chosen such that they could in principle be grasped with identical movements (i.e., relevant sizes were identical such that the final grips consisted of identical separations of the fingers and no parts of the objects constituted obstacles for the movement). Nevertheless, participants took object shape into account and grasped the bar with a larger maximum grip aperture and a different hand angle than the disc. In 20% of the trials, the object changed its shape from bar to disc or vice versa early or late during the movement. If there was enough time (early perturbations), grasps were often adapted in flight to the new shape. These results show that the motor system takes into account even small and seemingly irrelevant changes of object shape and adapts the movement in a fine-grained manner. Although this adaptation might seem computationally expensive, we presume that its benefits (e.g., a more comfortable and more accurate movement) outweigh the costs.
关于物体形状的视觉编码如何影响抓握动作，目前所知甚少。我们通过研究形状扰动对抓握的影响来解决这个问题。26名参与者抓握一个圆盘或一根杆，选择这两种物体是为了原则上可以用相同的动作抓握（即相关尺寸相同，使得最终的抓握由手指相同的间距组成，并且物体的任何部分都不会对动作构成障碍）。然而，参与者会考虑物体形状，抓握杆时的最大抓握孔径比抓握圆盘时更大，且手部角度也不同。在20%的试验中，物体在运动过程中的早期或晚期从杆变成圆盘，或者反之。如果有足够的时间（早期扰动），抓握动作通常会在运动过程中适应新形状。这些结果表明，运动系统会考虑到物体形状即使是微小且看似无关紧要的变化，并以精细的方式调整动作。尽管这种调整在计算上可能代价高昂，但我们推测其好处（例如，更舒适、更准确的动作）超过了成本。
