Dijkstra T M, Schöner G, Giese M A, Gielen C C
Laboratory of Medical Physics and Biophysics, University of Nijmegen, The Netherlands.
Biol Cybern. 1994;71(6):489-501. doi: 10.1007/BF00198467.
When standing human subjects are exposed to a moving visual environment, the induced postural sway displays varying degrees of coherence with the visual information. In our experiment we varied the frequency of an oscillatory visual display and analysed the temporal relationship between visual motion and sway. We found that subjects maintain sizeable sway amplitudes even as temporal coherence with the display is lost. Postural sway tended to phase lead (for frequencies below 0.2 Hz) or phase lag (above 0.3 Hz). However, we also observed at a fixed frequency, highly variable phase relationships in which a preferred range of phase lags is prevalent, but phase jumps occur that return the system into the preferred range after phase has begun drifting out of the preferred regime. By comparing the results quantitatively with a dynamical model (the sine-circle map), we show that this effect can be understood as a form of relative coordination and arises through an instability of the dynamics of the action-perception cycle. Because such instabilities cannot arise in passively driven systems, we conclude that postural sway in this situation is actively generated as rhythmic movement which is coupled dynamically to the visual motion.
当站立的人体受试者暴露于移动的视觉环境中时，诱发的姿势摆动与视觉信息呈现出不同程度的相关性。在我们的实验中，我们改变了振荡视觉显示的频率，并分析了视觉运动与摆动之间的时间关系。我们发现，即使与显示的时间相关性丧失，受试者仍保持相当大的摆动幅度。姿势摆动倾向于相位超前（频率低于0.2Hz）或相位滞后（频率高于0.3Hz）。然而，我们还观察到，在固定频率下，相位关系高度可变，其中相位滞后的首选范围普遍存在，但会出现相位跳跃，使系统在相位开始偏离首选范围后返回首选范围。通过将结果与动力学模型（正弦圆映射）进行定量比较，我们表明这种效应可以理解为一种相对协调的形式，并且是通过动作-感知循环动力学的不稳定性产生的。由于这种不稳定性不会在被动驱动的系统中出现，我们得出结论，在这种情况下的姿势摆动是作为有节奏的运动而主动产生的，并且与视觉运动动态耦合。
