Multifractal signatures of perceptual processing on anatomical sleeves of the human body

Abstract

Research into haptic perception typically concentrates on mechanoreceptors and their supporting neuronal processes. This focus risks ignoring crucial aspects of active perception. For instance, bodily movements influence the information available to mechanoreceptors, entailing that movement facilitates haptic perception. Effortful manual wielding of an object prompts feedback loops at multiple spatiotemporal scales, rippling outwards from the wielding hand to the feet, maintaining an upright posture, and interweaving to produce a nonlinear web of fluctuations throughout the body. Here, we investigated whether and how this bodywide nonlinearity engenders a flow of multifractal fluctuations that could support perception of object properties via dynamic touch. Blindfolded participants manually wielded weighted dowels and reported judgments of heaviness and length. Mechanical fluctuations on the anatomical sleeves, from hand to the upper body, as well as to the postural center of pressure, showed evidence of multifractality arising from nonlinear temporal correlations across scales. The modeling of impulse-response functions obtained from vector autoregressive (VAR) analysis revealed that distinct sets of pairwise exchanges of multifractal fluctuations entailed accuracy in heaviness and length judgments. These results suggest that the accuracy of perception via dynamic touch hinges on specific flowing patterns of multifractal fluctuations that people wear on their anatomical sleeves.Research into haptic perception typically concentrates on mechanoreceptors and their supporting neuronal processes, such as mechanoreceptor physiology and neuronal processing of passive somatosensory feedback [1,2]. Despite the significant insights of this research, this focus risks ignoring crucial aspects of active perception. For instance, bodily movements influence the information available to mechanoreceptors, entailing that movement facilitates haptic perception [3][4][5]. The present work investigated how bodywide mechanical interactions facilitate "dynamic" or "effortful" perception of heaviness and length of manuallywielded, visually-occluded objects. Specifically, we test two possibilities: first, that statistical structure in mechanical fluctuations flows across disparate anatomical locations (i.e., beyond the wielding hand) to coordinate perceptual judgments and, second, that the structure of this flow of statistical regularities impacts the accuracy of these judgments. The bodywide multifractal tensegrity (MFT) may simplify the degrees-of-freedom problem of spatiotemporally organizing afferent activityThe human body is highly complex, consisting of an enormous number of components, connected, interacting, and evolving via networks spanning multiple space and time scales. In traditional treatments of nervous-system networks, mechanoreceptor activity specifying the states of joints, muscles, and tendons flow through the spinal neurons to the brain. The challenge for this treatment is how the central executive can organize spati...

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