Bouni Alix, Arsac Laurent M, Chevalerias Olivier, Deschodt-Arsac Véronique
University of Bordeaux, CNRS, Laboratoire IMS, UMR 5218, 33405 Talence, France.
Centre Aquitain des Technologies de l'Information et Electroniques, 33400 Talence, France.
Sensors (Basel). 2025 May 7;25(9):2942. doi: 10.3390/s25092942.
Hand displacements during task-directed movements are not random, but exhibit fractal behavior. Wearable sensing e.g., accelerometer-derived hand movement fluctuations, could add a significant contribution to cognitive and behavioral sciences, by accounting for fractal dynamics. In particular, multifractal testing of fluctuation time series has been shown to reflect the adaptive use of cognition, i.e., cognitive flexibility. This important property might be enhanced by an improved mental state. Here, an experimental group (16 participants, 3 females) practiced 5 min cardiac coherence (CC) prior to a cognitive flexibility task and was compared to a control group (13 participants, 4 females). Accelerometer-derived hand motion was analyzed using multifractal-multiscale detrended fluctuation analysis (MFMS-DFA) during a task involving cognitive flexibility, the Wisconsin Card Sorting Test (WCST). WCST included four phases alternating the use of cards with original shapes or animal pictures developed for children in previous research. Hand behavioral time series derived from the wearable accelerometer effectively exhibited nonlinear multifractality as shown using linearized surrogates testing. Multifractal-multiscale metrics revealed significant effects of pre-task CC practice, specifically during WCST shape condition where CC participants showed lower multifractal degree despite similar performances (perseverative errors). We conclude that multifractal-multiscale testing of accelerometer-derived hand motion could make a significant contribution to interpreting changes in cognitive flexibility.
在任务导向运动过程中的手部位移并非随机的，而是呈现分形行为。可穿戴传感技术，例如由加速度计得出的手部运动波动，通过考虑分形动力学，可为认知科学和行为科学做出重大贡献。特别是，波动时间序列的多重分形测试已被证明能够反映认知的适应性使用，即认知灵活性。这种重要特性可能会因改善的心理状态而增强。在此，一个实验组（16名参与者，3名女性）在进行认知灵活性任务之前进行了5分钟的心脏相干性（CC）练习，并与一个对照组（13名参与者，4名女性）进行比较。在一项涉及认知灵活性的任务——威斯康星卡片分类测试（WCST）中，使用多重分形-多尺度去趋势波动分析（MFMS-DFA）对由加速度计得出的手部运动进行分析。WCST包括四个阶段，交替使用先前研究中为儿童开发的具有原始形状的卡片或动物图片。如通过线性化替代测试所示，从可穿戴加速度计得出的手部行为时间序列有效地呈现出非线性多重分形性。多重分形-多尺度指标揭示了任务前CC练习的显著影响，特别是在WCST形状条件下，尽管表现相似（持续性错误），但CC参与者的多重分形程度较低。我们得出结论，对由加速度计得出的手部运动进行多重分形-多尺度测试可为解释认知灵活性的变化做出重大贡献。
