In the previous work, we reported that tactile information (tactile slip) during finger sliding and reaching actions over a textured surface contributes to the control of the hand movement. More specifically, we observed a significant bias in the motion trajectories, which was explained by the tactile estimate accounted by the tactile flow model-i.e. a perceived motion direction always perpendicular to the ridge orientation, and its integration with the muscular-skeletal proprioceptive cues. However, to which extent this observed behavior also depends on the reaction force exerted by the surface ridges on the finger pad during the dynamic interaction still represents a largely unexplored research question. If not properly addressed, this point could rise the alternative explanation that the systematic bias is determined by the insufficient compensation of the reaction force by participants. In this article, we investigate the role of the lateral component of the reaction force on the surface plane (lateral force) in texture-related motion bias. We asked participants to slide their finger straight on a lubricated ridged plate towards a target goal displayed in a virtual reality environment. They exerted two different levels of normal force, which produced two different levels of lateral force during the finger interaction with the ridges. The effect of ridge orientation was found to be larger for the high compared to the low force level. However, also in the latter case, we still observed the same biased trajectories reported in our previous work, despite the negligible value of the lateral force. This supports our hypothesis that the motor bias arises from the integration of the tactile motion estimate, biased by the texture, and the other proprioceptive cues.

中文翻译：

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关于侧向力在执行任务期间纹理引起的运动偏差中的作用


在之前的工作中，我们报道了手指在纹理表面上滑动和到达动作期间的触觉信息（触觉滑动）有助于手部运动的控制。更具体地说，我们观察到运动轨迹存在显着偏差，这是通过触觉流模型所解释的触觉估计来解释的，即感知运动方向始终垂直于脊方向，及其与肌肉骨骼本体感觉线索的整合。然而，这种观察到的行为在多大程度上也取决于动态相互作用期间指垫上的表面脊施加的反作用力仍然是一个很大程度上尚未探索的研究问题。如果处理不当，这一点可能会产生另一种解释，即系统偏差是由参与者反作用力补偿不足决定的。在本文中，我们研究了表面平面上反作用力的横向分量（横向力）在纹理相关运动偏差中的作用。我们要求参与者将手指直接在润滑的脊板上滑动到虚拟现实环境中显示的目标。他们施加了两种不同水平的法向力，从而在手指与脊相互作用期间产生了两种不同水平的侧向力。研究发现，与低力水平相比，高力水平的脊方向的影响更大。然而，在后一种情况下，尽管侧向力的值可以忽略不计，但我们仍然观察到与我们之前的工作中报告的相同的偏置轨迹。这支持了我们的假设，即运动偏差来自于触觉运动估计的整合，受到纹理和其他本体感觉线索的偏差。