Department of Biomedical Engineering, Shinshu University, Ueda, Nagano, Japan; Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA.
Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA; Escuela Kinesiología, Facultad de Ciencias de la Rehabilitación, Universidad Andres Bello, Calle Quillota 980, Viña del Mar, Chile.
Hum Mov Sci. 2020 Dec;74:102714. doi: 10.1016/j.humov.2020.102714. Epub 2020 Nov 6.
We explored the phenomenon of unintentional finger force drift by using visual feedback on the force produced either by explicitly instructed (master) finger pairs or by non-instructed (enslaved) finger pairs. In particular, we drew contrasting predictions from two hypotheses: that force drifts represented consequences of drifts in effector referent coordinates at the level of individual fingers vs. at the level of finger modes (hypothetical variables accounting for the finger force interdependence). Subjects performed accurate force production with two fingers of a hand, index-ring or middle-little. They received visual feedback on the force produced either by the master fingers or by the other two, enslaved, fingers. The feedback scale was adjusted to ensure that the subjects did not know the difference between these two, randomly presented, conditions. Under feedback on the master finger force, enslaved force showed a consistent drift upward. Under feedback on the enslaved finger force, master force showed a consistent drift downward. The subjects were unaware of the force drifts, which could reach over 35% of the initial force magnitude. The data support the hypothesis on drifts in the referent coordinate at the level of individual digits, not finger modes, as the origin of unintentional force drifts. The consistent increase in the relative amount of force produced by the enslaved fingers suggests that the commonly used methods to quantify enslaving should include relatively brief force production tasks.
我们通过对明确指令的（主）手指对或非指令的（从）手指对产生的力提供视觉反馈，探索了无意手指力漂移现象。具体来说，我们从两个假设中得出了对比预测：力漂移代表了个体手指水平上的效应器参照坐标漂移的结果，还是代表了手指模式（假设变量解释了手指力的相互依存性）的结果。受试者用一只手的食指、中指和无名指进行了准确的力产生任务。他们接受了来自主手指或其他两个被奴役手指产生的力的视觉反馈。反馈刻度被调整，以确保受试者无法区分这两种随机呈现的情况。在主手指力的反馈下，从手指力表现出一致的向上漂移。在从手指力的反馈下，主手指力表现出一致的向下漂移。受试者没有意识到力的漂移，这些漂移可能达到初始力大小的 35%以上。数据支持了关于个体手指水平上参照坐标漂移的假设，而不是手指模式，这是无意力量漂移的起源。从手指产生的力的相对量持续增加，表明通常用于量化奴役的方法应该包括相对短暂的力产生任务。
