Neurocognition and Action Research Group, Faculty of Psychology and Sport Sciences, Bielefeld University, Bielefeld, Germany.
PLoS One. 2012;7(9):e43015. doi: 10.1371/journal.pone.0043015. Epub 2012 Sep 6.
There is ample evidence that people plan their movements to ensure comfortable final grasp postures at the end of a movement. The end-state comfort effect has been found to be a robust constraint during unimanual movements, and leads to the inference that goal-postures are represented and planned prior to movement initiation. The purpose of this study was to examine whether individuals make appropriate corrections to ensure comfortable final goal postures when faced with an unexpected change in action goal. Participants reached for a horizontal cylinder and placed the left or right end of the object into the target disk. As soon as the participant began to move, a secondary stimuli was triggered, which indicated whether the intended action goal had changed or not. Confirming previous research, participants selected initial grasp postures that ensured end-state comfort during non-perturbed trials. In addition, participants made appropriate on-line corrections to their reach-to-grasp movements to ensure end-state comfort during perturbed trials. Corrections in grasp posture occurred early or late in the reach-to-grasp phase. The results indicate that individuals plan their movements to afford comfort at the end of the movement, and that grasp posture planning is controlled via both feedforward and feedback mechanisms.
有充分的证据表明，人们会规划自己的动作，以确保在动作结束时能舒适地抓住目标。在单手运动中，终态舒适效应被发现是一个强有力的约束条件，这表明目标姿势在运动开始前就已经被表示和规划好了。本研究的目的是检验当面临动作目标的意外变化时，个体是否会做出适当的调整以确保舒适的最终目标姿势。参与者伸手去够一个水平圆柱体，并将物体的左或右端放入目标盘。一旦参与者开始移动，就会触发第二个刺激，指示目标动作是否发生了变化。与之前的研究一致，参与者在未受干扰的试验中选择了初始抓握姿势，以确保终态舒适。此外，参与者在受干扰的试验中对伸手抓握动作进行了适当的在线修正，以确保终态舒适。在伸手抓握阶段，抓握姿势的修正发生在早期或晚期。结果表明，个体规划自己的动作以在运动结束时获得舒适感，并且抓握姿势的规划是通过前馈和反馈机制来控制的。
