We used the theory of control with spatial referent coordinates (RC) to explore how young, healthy persons modify finger pressing force and match forces between the two hands. Three specific hypotheses were tested related to patterns of RC and apparent stiffness (defined as the slope of force-coordinate relation) used in the presence of visual feedback on the force and in its absence. The subjects used the right hand to produce accurate force under visual feedback; further the force could be increased or decreased, intentionally or unintentionally (induced by controlled lifting or lowering of the fingertips). The left hand was used to match force without visual feedback before and after the force change; the match hand consistently underestimated the actual force change in the task hand. The “inverse piano” device was used to compute RC and apparent stiffness. We found very high coefficients of determination for the inter-trial hyperbolic regressions between RC and apparent stiffness in the presence of visual feedback; the coefficients of determination dropped significantly without visual feedback. There were consistent preferred sharing patterns in the space of RC and apparent stiffness between the task and match hands across subjects. In contrast, there was much less consistency between the task and match hands in the magnitudes of RC and apparent stiffness observed in individual trials. Compared to the task hand, the match hand showed consistently lower magnitudes of apparent stiffness and, correspondingly, larger absolute magnitudes of RC. Involuntary force changes produced by lifting and lowering the force sensors led to significantly lower force changes compared to what could be expected based on the computed values of apparent stiffness and sensor movement amplitude. The results confirm the importance of visual feedback for stabilization of force in the space of hypothetical control variables. They suggest the existence of personal traits reflected in preferred ranges of RC and apparent stiffness across the two hands. They also show that subjects react to external perturbations, even when instructed “not to interfere”: Such perturbations cause unintentional and unperceived drifts in both RC and apparent stiffness.

我们使用带有空间参考坐标（RC）的控制理论来探索年轻健康的人如何改变手指的按压力并匹配两只手之间的力。测试了三个特定的假设，这些假设与存在和不存在力的视觉反馈时所使用的RC模式和表观刚度（定义为力-坐标关系的斜率）有关。受试者使用右手在视觉反馈下产生准确的力量；此外，可以有意或无意地增大或减小该力（由指尖的可控制举起或放下引起）。在改变力的前后，左手用来匹配力而没有视觉反馈；比赛手总是低估了任务手的实际力量变化。“反钢琴”设备用于计算RC和表观刚度。对于存在视觉反馈的情况下，RC与表观刚度之间的试验间双曲线回归，我们发现确定系数很高。在没有视觉反馈的情况下，确定系数显着下降。在RC空间中存在一致的首选共享模式，并且在跨主题的任务和匹配手之间存在明显的刚度。相反，任务和比赛手之间的RC大小和个别试验中观察到的刚度之间的一致性要差得多。与任务指针相比，匹配指针始终表现出较低的表观刚度大小，并且相应地具有较大的RC绝对大小。与基于视在刚度和传感器运动幅度的计算值可以预期的相比，通过提升和降低力传感器产生的非自愿力变化导致力变化明显更低。结果证实了视觉反馈对于假设的控制变量空间中的力稳定的重要性。他们认为个人特质的存在体现在RC的优选范围和两只手的明显僵硬感上。他们还表明，即使指示“不干扰”，受试者也会对外部干扰做出反应：此类干扰会导致RC和表观刚度的意外变化和意外变化。结果证实了视觉反馈对于假设控制变量空间中力稳定的重要性。他们认为个人特质的存在体现在RC的优选范围和两只手的明显僵硬感上。他们还表明，即使指示“不干扰”，受试者也会对外部干扰做出反应：此类干扰会导致RC和表观刚度的意外变化和意外变化。结果证实了视觉反馈对于假设的控制变量空间中的力稳定的重要性。他们认为个人特质的存在体现在RC的优选范围和两只手的明显僵硬感上。他们还表明，即使指示“不干扰”，受试者也会对外部干扰做出反应：此类干扰会导致RC和表观刚度的意外变化和意外变化。