Keele S W, Ivry R I, Pokorny R A
a University of Oregon.
J Mot Behav. 1987 Mar;19(1):96-114. doi: 10.1080/00222895.1987.10735402.
Previous work (Keele & Hawkins, 1982; Keele, Pokorny, Corcos, & Ivry, 1985) has suggested two general factors of coordination that differentiate people across a variety of motor movements, factors of timing and maximum rate of successive movements. This study provides comparable evidence for a third general factor of coordination, that of force control. Subjects who exhibit low variability in reproducing a target force with one effector, the finger, tend to show low variability with two other effectors, the foot and forearm. In addition, ability in force control cuts across different force ranges and across situations where force control is either the primary goal or the secondary goal. Force records obtained during a periodic tapping task show that, although force control is largely independent of timing, there are some interactions between the two factors. Force variation appears to distort timing a small amount in part because larger forces speed up implementation of movement, thereby shortening preceding intervals and lengthening following ones, and in part because force variation alters central-timing mechanisms.
先前的研究（基尔和霍金斯，1982年；基尔、波科尔尼、科科斯和伊夫里，1985年）表明，协调存在两个一般因素，这两个因素在各种运动动作中区分不同的人，即时间因素和连续动作的最大速率因素。本研究为协调的第三个一般因素，即力控制因素，提供了类似的证据。在用一个效应器（手指）再现目标力时表现出低变异性的受试者，在用另外两个效应器（脚和前臂）时往往也表现出低变异性。此外，力控制能力跨越不同的力范围以及力控制是主要目标或次要目标的不同情况。在周期性敲击任务中获得的力记录表明，尽管力控制在很大程度上独立于时间，但这两个因素之间存在一些相互作用。力的变化似乎会稍微扭曲时间，部分原因是较大的力会加快动作的执行速度，从而缩短之前的间隔并延长之后的间隔，部分原因是力的变化会改变中枢时间机制。
