Johnson Helen, Van Beers Robert J, Haggard Patrick
Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AR, England.
Exp Brain Res. 2002 Oct;146(4):451-9. doi: 10.1007/s00221-002-1200-z. Epub 2002 Sep 7.
Subjects' awareness of motor corrections was investigated in a double-step pointing task. An unpredictable lateral target displacement of 10 cm, either left or right, during an ongoing reaching movement led to corrections of the trajectory. Subjects were required either to follow the target (pointing) or move in the opposite direction (anti-pointing). The target jump elicited rapid corrections to the movement in the direction of the target shift. These corrections were in some sense involuntary as they sometimes occurred in anti-point trials, when subjects were instructed to correct in the opposite direction to the target jump. The instructed correction away from the target in anti-point trials occurred later than the correction towards the target in standard pointing. Subjects were also asked to report their awareness of the motor correction they had just made by immediately reproducing each movement. In normal pointing, subjects showed reduced and delayed awareness, suggesting that the corrections were at least partly automatic. Anti-pointing corrections did not show this dissociation between performance and awareness. We suggest that anti-point corrections, but not standard pointing corrections, involve an additional supervisory system. This system is characterised by its slow operation and its access to conscious awareness.
在一项双步指向任务中，研究了受试者对运动校正的意识。在持续的伸手动作过程中，不可预测地向左或向右横向目标位移10厘米会导致轨迹校正。受试者被要求要么跟随目标（指向），要么朝相反方向移动（反指向）。目标跳跃引发了朝着目标移动方向的快速校正。这些校正在某种意义上是不由自主的，因为它们有时会出现在反指向试验中，而此时受试者被指示朝与目标跳跃相反的方向校正。在反指向试验中远离目标的指示性校正比标准指向中朝着目标的校正出现得晚。还要求受试者通过立即重现每个动作来报告他们对刚刚进行的运动校正的意识。在正常指向下，受试者表现出意识减弱和延迟，这表明校正至少部分是自动的。反指向校正没有显示出表现与意识之间的这种分离。我们认为，反指向校正而非标准指向校正涉及一个额外的监督系统。该系统的特点是运行缓慢且可进入意识层面。
