Tresilian J R
Department of Human Movement Studies, University of Queensland, Brisbane, Australia.
Exp Brain Res. 1998 Jun;120(3):352-68. doi: 10.1007/s002210050409.
Obstacle avoidance strategies are of two basic but interrelated types: moving around an obstacle to that body parts do not come too close, and slowing down. In reaching-to-grasp, avoidance may involve the transport component, the grasp formation component, or both. There has been little research that has directly examined obstacle avoidance strategies during reaches-to-grasp. Several recent reports describe experiments in which reaches-to-grasp were made when nontarget objects were present in the workspace. The effects of these nontargets were interpreted as being due to their distracting effects rather than their obstructing effects. The results of these studies are reinterpreted as being due to the non-target's obstructing effects. The obstacle interpretation is more parsimonious and better predicts the pattern of results than the distractor interpretation. Predictions of the obstacle interpretation were examined in an experiment in which participants were required to reach to grasp a target in the presence of another object in various locations. The results were exactly in line with the interpretation of the object as an obstacle and the data show how grasp and transport movements are subtly adjusted so as to avoid potential obstacles. It is proposed that people move so as not to bring body parts within a minimum preferred distance from nontarget objects within the workspace. What constitutes the preferred distance in a particular context appears to depend upon the speed of movement and a variety of psychological factors related to the cost that a person attaches to a collision.
绕过障碍物以使身体部位不会靠得太近，以及减速。在伸手抓握时，避障可能涉及运输部分、抓握形成部分或两者。很少有研究直接考察伸手抓握过程中的避障策略。最近的几份报告描述了在工作空间中存在非目标物体时进行伸手抓握的实验。这些非目标物体的影响被解释为是由于它们的干扰作用而非阻碍作用。这些研究的结果被重新解释为是由于非目标物体的阻碍作用。与干扰物解释相比，障碍物解释更简洁，并且能更好地预测结果模式。在一项实验中检验了障碍物解释的预测，在该实验中，要求参与者在不同位置存在另一个物体的情况下伸手去抓握一个目标。结果与将该物体视为障碍物的解释完全一致，数据显示了抓握和运输动作是如何巧妙调整以避免潜在障碍物的。有人提出，人们移动的方式是为了不让身体部位与工作空间内的非目标物体保持在最小偏好距离之内。在特定情境中构成偏好距离的因素似乎取决于运动速度以及与人们赋予碰撞的代价相关的各种心理因素。
