Discrete and cyclical units of action in a mixed target pair aiming task
Discrete and cyclical units of action in a mixed target pair aiming task
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DOI：
10.1007/s00221-003-1471-z
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发表时间：
2003-06-01
影响因子：
2
通讯作者：
Shea, CH
中科院分区：
文献类型：
--
作者：
Buchanan, JJ;Park, JH;Shea, CH
两个实验解决了离散和循环单元作为可能的基本动作单元的问题，可用于根据任务约束构建复杂的动作。实验研究了低精度和高精度约束对有节奏的瞄准运动中末端执行器运动的影响。两个实验都在三个精度约束下使用了 Fitts 型任务：（1）大目标配对 - 低运动难度指数（ID），（2）小目标配对 - 高 ID，以及（3）混合目标配对 - 一个目标高 ID，另一个目标低 ID。实验 I 是一项 1 自由度 (df) 任务，要求受试者使用肘部屈曲-伸展运动跨越一对目标中的目标的内边缘。实验 II 使用 2-df 任务，要求受试者使用手持式触控笔在目标对中的目标之间来回敲击。在这两个实验中，低 ID 条件下的末端执行器运动是循环的，末端执行器的运动与极限循环吸引子描述一致，而在高 ID 条件下，末端执行器运动是离散的，与定点吸引子描述一致。混合目标配对在末端执行器的动力学中产生了离散和循环特征，这表明离散和循环动作单元的功能链接作为最佳运动解决方案。支持上述陈述的证据可见于运动时间 (MT)、停留时间、MT 加速和减速比例的运动学测量以及和谐性测量中 (Guiard 1993, Acta Psychol 82:139-159; Guiard 1997, Hum Mov Sci 16:97-131)。在混合目标条件下的扩展练习揭示了练习中对循环运动的偏见。结果表明，以极限环和定点吸引子表示的离散和循环运动是运动系统用于构造更复杂的动作序列的基本动作单位。参考协调结构和广义运动程序作为基本动作单位来讨论结果。还讨论了与快速瞄准任务中的视觉反馈处理和运动制动有关的问题。
Two experiments addressed the issue of discrete and cyclical units as possible basic units of action that might be used to construct complex actions based on task constraints. The experiments examined the influence of low and high accuracy constraints on the end-effector's motion in rhythmical aiming movements. Both experiments utilized a Fitts-type task under three accuracy constraints: (1) big target pairing-low index of movement difficulty (ID), (2) small target pairing-high ID, and (3) mixed target pairing-one target high ID and the other target low ID. Experiment I was a 1-degree-of-freedom (df) task that required subjects to crossover the inside edge of targets in a target pair using elbow flexion-extension motions. Experiment II used a 2-df task that required subjects to tap back and forth between targets in a target pair using a hand-held stylus. In both experiments, end-effector motion in the low ID condition was cyclical with the end-effector's motion consistent with a limit-cycle attractor description, while in the high ID condition end-effector motion was discrete and consistent with a fixed-point attractor description. The mixed target pairing produced both discrete and cyclical features in the end-effector's dynamics that suggested a functional linking of discrete and cyclical units of action as the optimal movement solution. Evidence supporting the above statements was found in the kinematic measures of movement time (MT), dwell time, proportion of MT accelerating and decelerating, and in a measure of harmonicity (Guiard 1993, Acta Psychol 82:139-159; Guiard 1997, Hum Mov Sci 16:97-131). Extended practice in the mixed target condition revealed a bias towards cyclical motion with practice. The results demonstrate that discrete and cyclical motion, represented as limit-cycle and fixed-point attractors, are basic units of action that the motor system uses in constructing more complex action sequences. The results are discussed with reference to coordinative structures and the generalized motor program as basic units of action. Issues pertaining to visual feedback processing and movement braking in rapid aiming tasks are also discussed.