Research Institute MOVE, Faculty of Human Movement Sciences, VU University, Van der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands.
Exp Brain Res. 2010 Mar;201(2):221-7. doi: 10.1007/s00221-009-2032-x. Epub 2009 Oct 9.
When searching for a target with eye movements, saccades are planned and initiated while the visual information is still being processed, so that subjects often make saccades away from the target and then have to make an additional return saccade. Presumably, the cost of the additional saccades is outweighed by the advantage of short fixations. We previously showed that when the cost of passing the target was increased, by having subjects manually move a window through which they could see the visual scene, subjects still passed the target and made return movements (with their hand). When moving a window in this manner, the eyes and hand follow the same path. To find out whether the hand still passes the target and then returns when eye and hand movements are uncoupled, we here compared moving a window across a scene with moving a scene behind a stationary window. We ensured that the required movement of the hand was identical in both conditions. Subjects found the target faster when moving the window across the scene than when moving the scene behind the window, but at the expense of making larger return movements. The relationship between the return movements and movement speed when comparing the two conditions was the same as the relationship between these two when comparing different window sizes. We conclude that the hand passing the target and then returning is not directly related to the eyes doing so, but rather that moving on before the information has been fully processed is a general principle of visuomotor control.
当通过眼球运动搜索目标时，眼跳在视觉信息仍在处理时就已被规划和启动，因此实验对象通常会将眼跳偏离目标，然后不得不进行额外的返回眼跳。据推测，额外眼跳的代价超过了短注视的优势。我们之前曾表明，当通过目标的成本增加时，通过让实验对象手动移动一个窗口，他们可以通过该窗口看到视觉场景，实验对象仍然会通过目标并进行返回运动（用手）。以这种方式移动窗口时，眼睛和手会沿着相同的路径移动。为了查明当眼动和手动分离时，手是否仍会通过目标然后返回，我们在这里比较了在场景中移动窗口与在固定窗口后面移动场景。我们确保在两种情况下，手的所需移动是相同的。与在窗口后面移动场景相比，实验对象在通过窗口移动场景时更快地找到了目标，但代价是更大的返回运动。当比较两种情况时，返回运动与运动速度之间的关系与比较不同窗口大小时这些关系相同。我们得出结论，手通过目标然后返回与眼睛这样做并没有直接关系，而是在信息尚未完全处理之前就继续移动是视动控制的一般原则。
