Kelso J A, Southard D L, Goodman D
Science. 1979 Mar 9;203(4384):1029-31. doi: 10.1126/science.424729.
Movement time varies as a function of amplitude and requirements for precision, according to Fitts' law, but when subjects perform two-handed movements to targets of widely disparate difficulty they do so simultaneously. The hand moving to an "easy" target moves more slowly to accommodate its "difficult" counterpart, yet both hands reach peak velocity and acceleration synchronously. This result suggests that the brain produces simultaneity of action not by controlling each limb independently, but by organizing functional groupings of muscles that are constrained to act as a single unit.
根据菲茨定律，运动时间会随着幅度和精度要求而变化，但当受试者同时向难度差异很大的目标进行双手运动时，他们会同时完成。移向“简单”目标的手移动得更慢，以适应其“困难”的对应目标，但两只手会同时达到峰值速度和加速度。这一结果表明，大脑产生动作同步性并非通过独立控制每个肢体，而是通过组织受约束以作为单个单元起作用的肌肉功能组来实现的。
