Walter C B, Swinnen S P, Corcos D M, Pollatou E, Pan H Y
School of Kinesiology, University of Illinois at Chicago 60680-1516, USA.
Psychol Res. 1997;60(4):202-13. doi: 10.1007/BF00419405.
The present studies examined the nature of kinematic interlimb interference during bilateral elbow movements of 1:1, 2:1 and 3:1 frequency ratios and the manner in which subjects cope with coordination bias. Analysis of movement trajectories in the first experiment indicated progressively greater angular velocity assimilation across 2:1 and 3:1 conditions. The desired temporal relationship was maintained by slowing or pausing the low-frequency movement at peak extension while the high-frequency arm produced intervening cycles. An increase in amplitude was also evident for concurrent, homologous cycles. Movement smoothness was emphasized and additional practice was provided in a second experiment. This resulted in dissociated peak angular velocity between limbs and eliminated hesitations and amplitude effects. Bias was still evident, however, as an intermittent approach toward a 1:1 ratio within each cycle. This systematic tendency was somewhat greater at the lower of two absolute frequency combinations but was not influenced by the role of each arm in producing the higher or lower frequency movement. The findings from the first experiment suggest that subjects initially accommodate interlimb kinematic assimilation, while producing the intended timing ratio, by intermittently slowing or pausing the lower-frequency movement. This attenuates the need for bilaterally-disparate movement parameters and provides additional time for organizing residual kinematic differences, perhaps reducing "transient coupling." Evidence from the second experiment indicates that subtle relative motion preferences are still evident following sufficient practice to perform the movements smoothly. The within-cycle locations of the points of greatest interlimb bias for the 2:1 rhythms were positively displaced from those previously observed for 1:1 oscillations. The persistent coordination tendencies noted in both experiments perhaps reflect an assimilation/compensation cycle and constitute one potential source of the systematic error that often emerges during the acquisition of complex skills.
本研究考察了在频率比为1:1、2:1和3:1的双侧肘部运动过程中运动学肢体间干扰的本质，以及受试者应对协调偏差的方式。第一个实验中对运动轨迹的分析表明，在2:1和3:1的条件下，角速度同化逐渐增强。通过在峰值伸展时减慢或暂停低频运动，同时高频手臂产生中间周期，从而维持所需的时间关系。同时出现的同源周期的振幅也明显增加。在第二个实验中强调了运动的平滑性并提供了额外的练习。这导致了肢体间峰值角速度的分离，并消除了犹豫和振幅效应。然而，偏差仍然明显，表现为每个周期内间歇性地趋向于1:1的比例。这种系统趋势在两个绝对频率组合中较低的那个频率下略强，但不受每只手臂在产生较高或较低频率运动中所起作用的影响。第一个实验的结果表明，受试者最初通过间歇性地减慢或暂停低频运动来适应肢体间的运动学同化，同时产生预期的时间比例。这减少了对双侧不同运动参数的需求，并为组织剩余的运动学差异提供了额外的时间，可能减少了“瞬时耦合”。第二个实验的证据表明，在经过足够的练习以平稳执行运动之后，细微的相对运动偏好仍然明显。2:1节奏下肢体间偏差最大点在周期内的位置相对于之前观察到的1:1振荡时的位置有正向偏移。在两个实验中都观察到的持续协调趋势可能反映了一个同化/补偿周期，并且构成了在复杂技能习得过程中经常出现的系统误差的一个潜在来源。
