Department of Psychology, Grinnell College, Grinnell, IA 50112, USA.
UNC-NC State Joint Department of Biomedical Engineering, UNC-Chapel Hill, Chapel Hill, NC 27514, USA.
Hum Mov Sci. 2021 Apr;76:102771. doi: 10.1016/j.humov.2021.102771. Epub 2021 Feb 15.
Visually guided postural control emerges in response to task constraints. Task constraints generate physiological fluctuations that foster the exploration of available sensory information at many scales. Temporally correlated fluctuations quantified using fractal and multifractal metrics have been shown to carry perceptual information across the body. The risk of temporally correlated fluctuations is that stable sway appears to depend on a healthy balance of standard deviation (SD): too much or too little SD entails destabilization of posture. This study presses on the visual guidance of posture by prompting participants to quietly stand and fixate at distances within, less than, and beyond comfortable viewing distance. Manipulations of the visual precision demands associated with fixating nearer and farther than comfortable viewing distance reveals an adaptive relationship between SD and temporal correlations in postural fluctuations. Changing the viewing distance of the fixation target shows that increases in temporal correlations and SD predict subsequent reductions in each other. These findings indicate that the balance of SD within stable bounds may depend on a tendency for temporal correlations to self-correct across time. Notably, these relationships became stronger with greater distance from the most comfortable viewing and reaching distance, suggesting that this self-correcting relationship allows the visual layout to press the postural system into a poise for engaging with objects and events. Incorporating multifractal analysis showed that all effects attributable to monofractal evidence were better attributed to multifractal evidence of nonlinear interactions across scales. These results offer a glimpse of how current nonlinear dynamical models of self-correction may play out in biological goal-oriented behavior. We interpret these findings as part of the growing evidence that multifractal nonlinearity is a modeling strategy that resonates strongly with ecological-psychological approaches to perception and action.
视觉引导的姿势控制是对任务约束的反应。任务约束会产生生理波动，从而促进在多个尺度上探索可用的感觉信息。使用分形和多重分形度量来量化的时间相关波动已被证明可以在整个身体中传递感知信息。时间相关波动的风险在于，稳定的摆动似乎取决于标准偏差（SD）的健康平衡：SD 过多或过少都会导致姿势不稳定。本研究通过提示参与者在舒适观看距离内、小于舒适观看距离和大于舒适观看距离处安静站立并固定注视，进一步推动了姿势的视觉引导。对固定更近和更远距离时与视觉精度相关的需求的操作，揭示了 SD 和姿势波动时间相关之间的自适应关系。改变固定目标的观察距离表明，时间相关和 SD 的增加预测了彼此的后续减少。这些发现表明，在稳定范围内的 SD 平衡可能取决于时间相关在整个时间内自我纠正的趋势。值得注意的是，这些关系在距离最舒适的观看和到达距离越大时变得更强，这表明这种自我纠正关系允许视觉布局将姿势系统置于与物体和事件接触的平衡状态。纳入多重分形分析表明，归因于单分形证据的所有效应都可以更好地归因于跨尺度非线性相互作用的多重分形证据。这些结果提供了一个线索，说明当前用于自我纠正的非线性动力模型如何在生物目标导向行为中发挥作用。我们将这些发现解释为越来越多的证据的一部分，即多重分形非线性是一种与生态心理学方法对感知和行为产生强烈共鸣的建模策略。
