Claims for Effector Independence and Generalized Motor Programs: Evidence from Handwriting

人类的动作，从最简单的指向动作到更复杂的多手势动作，都遵循预先存在的心理计划（通常称为运动程序）所包含的方向。虽然我们很少意识到这样的程序的存在，但它们的目的是组织对肌肉的命令，以便运动可以在最小程度上依赖缓慢的、基于反馈的、纠错的过程。虽然在这一点上有普遍的共识，但运动程序的结构还远不清楚。运动控制理论家推测运动程序可以普遍化。这一想法源于对计算机编程子程序的类比，它表明，当一个动作即将发生时，内存中的运动程序具有形式参数，这些参数被实际的、特定于情境的值所取代。本研究将探索电机程序概括的经验现实，以及描述如何实现这种概括的各种建议的含义。这些问题将在书写和绘图运动领域得到解决。虽然本研究将研究跨几个运动参数的运动程序泛化，例如，运动速度或大小，但特别强调的是一种特殊形式的运动程序泛化，称为效应器独立性。这个术语描述了单个运动程序驱动几个效应器系统中的任何一个产生与该程序相关的运动的能力。效应器独立性声称从几个非正式的比较中得到了经验支持，这些比较是用手腕和手指书写的单词与用整个手臂（如黑板上）书写的相同单词的形状。在这种情况下，不同的效应器系统可能包括右手、左手、整个右臂，甚至一只脚。正是这种运动系统的多样性，以及它们不同的关节结构、肌肉系统和神经支配类型，使得效应器独立性的主张如此诱人。这项研究将沿着两条路线进行。第一部分将考察先前学过的动作，对动作的形状、时间、力和速度的破坏性影响，这些影响是由操纵实验情境的许多方面引起的。在第二项研究中，人们将在一组条件下学习新的动作，并研究他们将所学知识转移到新条件下的能力。从这项研究中获得的关于运动程序的结构和功能的见解将有潜在的应用于需要协调运动的技能训练，运动障碍的诊断和治疗，以及机器人系统中运动的规划和表示。

Human movements, from the simplest pointing movement to more elaborate multi-gesture movements, follow directions contained in pre-existing mental plans, often called motor programs. Although we are seldom aware of the existence of such programs, their purpose is to structure commands to the muscles so that movements can be made with minimal reliance on slow, feedback-based, error- correcting processes. While there is general agreement on this point, the structure of motor programs is far from clear. Motor control theorists have speculated that motor programs can be generalized. This idea, which stems from an analogy to subprograms in computer programming, suggests that motor programs in memory have formal parameters that are replaced with actual, situation-specific values when a movement is about to be made. This research will explore the empirical reality of motor-program generalization as well as the implications of various proposals describing how such generalizations might be implemented. These issues will be addressed in the domains of handwriting and drawing movements. While this research will investigate motor program generalization across several movement parameters, e.g., movement speed or size, special emphasis will be given to a particular form of motor- program generalization known as effector independence. This term describes the ability of a single motor program to drive any of several effector systems to produce movement associated with that program. Effector independence is claimed to draw empirical support from several informal comparisons of the shapes of words written using only the wrist and fingers versus those same words written with the whole arm, as on a chalkboard. In this context, different effector systems might include the right hand, the left hand, the whole right arm, or even a foot. It is this diversity of the movement systems involved, with their different joint configurations, muscle systems, and types of nerve innervation, that makes the claim of effector independence so tantalizing. This research will proceed along two lines. The first will examine, for previously learned movements, the disruptive effects on the movement's shape, timing, force, and velocity caused by manipulating a number of aspects of the experimental situation. In the second line of research, people will learn novel movements under one set of conditions, and their ability to transfer that learning to new conditions will be studied. The insights about the structure and function of motor programs gained from this research will have potential application to the training of skills requiring coordinated movement, the diagnosis and treatment of movement disorders, and the planning and representation of movements in robotic systems.