Mrotek Leigh A, Flanders Martha, Soechting John F
Department of Neuroscience, University of Minnesota, 6-145 Jackson Hall, 321 Church Street S E, Minneapolis, MN 55455-0250, USA.
Exp Brain Res. 2004 May;156(1):94-103. doi: 10.1007/s00221-003-1764-2. Epub 2004 Jan 13.
There are time delays in visuomanual and oculomotor pathways, and some of these time delays may be due to the finite time required to process visual motion signals and to extract accurate information about the speed and direction of the motion. The present experiments were designed to ascertain the time required to obtain a reliable estimate of the direction of target motion. Subjects were asked to indicate the final direction of a moving target, which abruptly changed direction and shortly thereafter disappeared, by pointing to its expected emergence at the boundary of an occlusion. Subjects made small but consistent errors that overestimated the target's change in direction. These errors depended little on the amount of time the target was visible (ranging from 50 to 400 ms) after it changed direction. Pointing direction was strongly correlated with gaze, which was dominated by a saccade initiated shortly after the target changed direction. The pointing errors were explained by the fact that the saccade always intercepted the (occluded) target, but then continued in the same direction toward the boundary of the occlusion. The analysis reveals that target direction was estimated accurately even at the shortest viewing time.
视觉手动和动眼神经通路中存在时间延迟，其中一些时间延迟可能是由于处理视觉运动信号以及提取有关运动速度和方向的准确信息所需的有限时间。本实验旨在确定获得目标运动方向可靠估计所需的时间。受试者被要求通过指向目标在遮挡边界处预期出现的位置，来指示突然改变方向并在不久后消失的移动目标的最终方向。受试者出现了虽小但一致的错误，高估了目标的方向变化。这些错误几乎不依赖于目标改变方向后可见的时间量（范围从50到400毫秒）。指向方向与注视密切相关，注视主要由目标改变方向后不久发起的一次扫视主导。指向错误可以解释为扫视总是拦截（被遮挡的）目标，但随后继续朝着遮挡边界的相同方向移动。分析表明，即使在最短的观察时间内，目标方向也能被准确估计。
