Endo Satoshi, Wing Alan M, Bracewell R Martyn
Behavioural Brain Sciences Centre, School of Psychology, The University of Birmingham, England, UK.
J Mot Behav. 2011;43(6):427-31. doi: 10.1080/00222895.2011.621996. Epub 2011 Oct 17.
When using precision grip to pick up objects, there are many possible pairs of grasp points that permit the thumb and index finger to exert opposed forces for secure grip. Previously, it was shown that individuals select grasp points so that the line between them (grasp axis) passes through or near the center of mass (CoM), thus minimizing the torque around the grasp axis during lifting. The accuracy of grasp axis selection depended on object spatial symmetry, indicating the importance of vision. The authors investigated how grasp point selection is influenced by haptic as well as visual information. Ten participants lifted cuboids whose CoM was located either symmetrically in the geometric center or asymmetrically toward one end. Results for the asymmetric cuboid revealed that grasp points migrated toward the asymmetric CoM from the geometric center. This was more pronounced in the presence of visual cues that reliably indicated the location of CoM. The results suggest that grasp point selection is influenced by a multimodal representation of CoM.
当使用精确抓握来拿起物体时，有许多可能的抓握点对，可使拇指和食指施加相反的力以实现稳固抓握。此前的研究表明，个体选择抓握点时会使它们之间的连线（抓握轴）穿过或靠近质心（CoM），从而在提起物体时使围绕抓握轴的扭矩最小化。抓握轴选择的准确性取决于物体的空间对称性，这表明视觉的重要性。作者研究了触觉信息以及视觉信息如何影响抓握点的选择。10名参与者拿起长方体，这些长方体的质心要么对称地位于几何中心，要么不对称地偏向一端。对于不对称长方体的结果显示，抓握点从几何中心向不对称的质心迁移。在存在可靠指示质心位置的视觉线索时，这种情况更为明显。结果表明，抓握点的选择受到质心的多模态表征的影响。
