Gradual molding of the hand to object contours
Gradual molding of the hand to object contours
复制标题
DOI：
10.1152/jn.1998.79.3.1307
复制
发表时间：
1998-03-01
影响因子：
2.5
通讯作者：
Soechting, JF
中科院分区：
文献类型：
--
作者：
Santello, M;Soechting, JF
受试者被要求用与拇指相对的脏手指伸手抓住 15 个类似大小的物体。这些物体的轮廓各不相同：有些对手指来说是凹面，有些是平坦的，还有一些是凸面。在伸手运动期间记录手指的掌指关节和近端指间关节的屈曲/伸展。我们使用判别分析、聚类分析和信息论来确定手部形状沿凸/凹梯度受物体形状影响的程度。在伸手动作的中间大约达到手的最大光圈。当时，手的姿势受到要抓握物体形状的影响，但并不完善。随着手接近物体，手势传递的有关物体形状的信息逐渐单调增加，在手握住物体时达到最大值。我们还要求受试者塑造手的形状，以便在不移动手臂的情况下抓住物体。他们在这项任务上的表现较差，因为手的形状可以区分较少的物体，并且试验间的变异性比运动的远端和近端分量相连时更大。结果表明，手只是逐渐适应要抓握的物体的轮廓。由于运动的其他参数（例如运动方向）在运动的早期就已经被完全指定，因此结果还表明运动不同方面的指定并不是以统一的速率发展的。
Subjects were asked to reach to and to grasp 15 similarly sized objects with the foul fingers opposed to the thumb. The objects' contours differed: some presented a concave surface to the fingers, others a flat one, and yet others a convex surface. Flexion/extension at the metacarpal-phalangeal and proximal interphalangeal joints of the fingers was recorded during the reaching movement. We used discriminant analysis, cluster analysis, and information theory to determine the extent to which the shape of the hand was affected by the objects' shapes along a convexity/concavity gradient. Maximum aperture of the hand was reached about midway in the reaching movement. At that time, the hand's posture was influenced by the shape of the object to be grasped but imperfectly. The information transmitted by hand posture about object shape increased gradually and monotonically as the hand approached the object, reaching a maximum at the time the object was in the grasp of the hand. We also asked subjects to shape the hand so as to grasp the object without moving the arm. Their performance was poorer on this task in the sense that hand shape discriminated among fewer objects and that trial-to-trial variability was greater than when the distal and proximal components of the motion were linked. The results indicate that the hand is molded only gradually to the contours of an object to be grasped. Because other parameters of the motion, such as movement direction, for example, already are specified fully early on in a movement, the results also suggest that the specification of diverse aspects of a movement does not evolve at a uniform rate.