Ranganathan Rajiv, Newell Karl M
Department of Kinesiology, 266 Recreation Building, The Pennsylvania State University, University Park, PA 16802-6501, USA.
Exp Brain Res. 2008 Apr;186(4):561-70. doi: 10.1007/s00221-007-1259-7. Epub 2008 Jan 9.
The aim of the current study was to examine the influence of visual feedback on compensatory variations in force within and between trials. In Experiment 1, the task was to maintain a constant force of 5 N for 15 s using both index fingers. In Experiment 2, the task was to produce discrete force pulses such that the peak value of the sum of the two finger forces was 5 N. In both experiments, there were three conditions that manipulated the amount of visual feedback of the force trace. Results showed that the within-trial correlations between the finger forces increased when feedback was degraded, indicating that the two fingers were increasingly constrained toward acting as a single unit. Similarly, between-trial correlations showed that the amount of error compensation decreased when feedback was removed, indicating that participants produced a smaller set of goal equivalent solutions. It appears that feedback has a dual role in coordination-removing the constraints on the degrees of freedom within trials, and facilitating the utilization of redundancy between trials. The distinction between these two classes of variation is central to understanding the redundancy problem in motor control.
本研究的目的是检验视觉反馈对试验内和试验间力量代偿性变化的影响。在实验1中，任务是用两只食指维持5牛的恒定力量15秒。在实验2中，任务是产生离散的力量脉冲，使两只手指力量总和的峰值为5牛。在两个实验中，都有三种条件来操纵力量轨迹的视觉反馈量。结果表明，当反馈减弱时，手指力量之间的试验内相关性增加，这表明两只手指越来越受到限制，趋向于作为一个单一单元起作用。同样，试验间相关性表明，当反馈被去除时，误差补偿量减少，这表明参与者产生的目标等效解的集合更小。看来反馈在协调中具有双重作用——消除试验内自由度的限制，并促进试验间冗余的利用。这两类变化之间的区别对于理解运动控制中的冗余问题至关重要。
