Sensory coupling in tool use

关于我们手的位置的感觉信息通常是多模式的，特别是视觉和本体感觉。不同形式的感觉整合导致单只手在一个位置上的感知。在工具使用中，视觉和本体感觉信息通常不再与单一对象手相关，而是与不同的对象相关，分别是工具和手的有效部分。工具有效部分的运动通过所谓的运动学变换与手的运动联系在一起。在最流行的研究适应新运动学变换的实验范式中，计算机显示器上光标的运动方向是相对于手运动的方向旋转的。对这一范式进行修正的初步研究揭示了光标和手方向的感觉耦合，即手和光标移动的感知方向的相互偏差，尽管不同位置的不同物体在不同的平面上移动。该项目的目的是促进对这种特殊类型的感觉耦合的了解。第一系列实验用于测试被广泛接受的近最佳感觉整合模型的扩展。这些模型是针对不同感觉模式涉及单个对象的单个属性的情况而开发的。它们应被推广到这样的情况，其中不同的感觉形式指的是两个不同对象的属性，其运动通过运动学变换而联系在一起。进一步的一系列实验用来确定决定工具使用中感觉耦合的强度和不对称性的因素。这些系列中的第一个系列用于比较不同的运动学转换，第二个系列用于评估学习运动学转换的效果，不同的练习方案可能会有所不同。在第三个系列中，测试了可能影响联轴器强度的其他因素。这些因素包括关于手运动的本体感觉信息和关于光标运动的视觉信息之间的时间延迟，以及手运动的速度曲线和伴随的光标运动之间的相关性。最后，作为几个计划实验的副产品，基于明确的心理物理判断的感觉耦合的估计将与基于一种特定的间接测量感知的手位置的估计进行比较。

Sensory information on the position of our hand is typically multimodal, visual and proprioceptive in particular. Sensory integration of the different modalities results in the perception of a single hand in a single position. In tool use, visual and proprioceptive information typically relate no longer to a single object, the hand, but to different objects, the effective part of the tool and the hand, respectively. Movements of the effective part of the tool are related to hand movements by the so-called kinematic transformation. In the most popular experimental paradigm for the study of adaptation to novel kinematic transformations, the direction of the motion of a cursor on a computer monitor is rotated relative to the direction of hand movement. Preliminary studies with a modification of this paradigm revealed sensory coupling of cursor and hand direction, that is, mutual biases of the perceived directions of hand and cursor movements, in spite of different objects in different locations that move in different planes. The purpose of the proposed project is to advance knowledge of this particular type of sensory coupling.A first series of experiments serves to test extensions of widely accepted models of near-optimal sensory integration. These models have been developed for situations in which different sensory modalities refer to a single property of a single object. They shall be generalized to situations, in which the different sensory modalities refer to a property of two different objects, the movements of which are related by a kinematic transformation. Further series of experiments serve to identify factors which determine the strength and the asymmetry of sensory coupling in tool use. The first of these series is designed to compare different kinematic transformations, the second series to assess the effects of learning the kinematic transformation which might differ for different practice regimen. In the third series additional factors are tested that are likely to affect coupling strength. Among these factors are temporal delays between proprioceptive information on hand movements and visual information on cursor motions, and the correlations between the velocity profiles of hand movements and accompanying cursor motions. Finally, as a by-product of several of the planned experiments, estimates of sensory coupling based on explicit psychophysical judgements will be compared with estimates based on a particular kind of indirect measure of the sensed hand position.