Global broadcasting of local fractal fluctuations in a bodywide distributed system supports perception via effortful touch

Mangalam, Madhur; Carver, Nicole S.; Kelty-Stephen, Damian G.

doi:10.1016/j.chaos.2020.109740

Cited by 32 publications

(29 citation statements)

References 74 publications

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“…The strength of these exchanges of multifractal fluctuations amongst degrees of freedom indexed the accuracy of perception. These results strengthen the view that nonlinear interactions entailed by the bodywide MFT support the flow of mechanical information supporting the coordination of perceptual judgments of object heaviness and length [30].…”

Section: Discussionsupporting

confidence: 80%

“…Fractal fluctuations at any point in the body might spread through the rest of the body like contagion and this multifractal spread through the body matters for shaping perceptual judgments. Indeed, the bodywide flow of fractality indexes the flow of afferent information used to derive perceptual judgments for manually-hefted, visually-occluded objects, predicting individual differences in perceptual judgments from individual differences in bodywide flows of fractal fluctuations [30].…”

Section: Could Flow Of Multifractal Fluctuations Support Perception Vmentioning

confidence: 99%

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

Mangalam

Carver²,

Kelty-Stephen

2020

Preprint

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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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Section: Discussionsupporting

confidence: 80%

Section: Could Flow Of Multifractal Fluctuations Support Perception Vmentioning

confidence: 99%

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

Mangalam

Carver²,

Kelty-Stephen

2020

Preprint

Self Cite

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“…This organization entails a specifically multifractal geometry that embodies multiple scale-invariant patterns of behavior (e.g., microsaccades within the saccades that intersperse larger saccades by the eye and turns by the head) across time and across space. CoP fractality has repeatedly borne a consistent relationship to perceptual judgments of visual and haptic stimuli [24][25][26][27][28][29], and research into perceptual tasks (e.g., manually wielding an object to judge heaviness or length) while standing shows that a bodywide flow of fractal fluctuations precedes and shapes the verbal articulation of perceptual judgments [30,31]. Hence, a fractal flow within posture seems to support information flow and might provide a glimpse of the control policy emerging from bodily situation in task constraints.…”

Section: Perceptual Constraints On Postural Stability Could Reshape Imentioning

confidence: 94%

“…However, past evidence suggests that fluctuations in the upper body moderate the use of visual information beyond and possibly in collaboration with the retina's microsaccades. CoP and movements of the upper extremities exhibit a close mutual predictive relationship in fractal and multifractal fluctuations even without involving a significant role of torso fluctuations [30,31]. Indeed, should tensegrity-themed metaphors for the movement system be apt [18], then we can expect relatively less local relationships, and CoM may be one of the multiple intermediary links in the anatomical change that need not always participate in controlling posture.…”

Section: Glimpses Of a Possible Control Policy For Visually Guided Qumentioning

confidence: 99%

Multifractal roots of suprapostural dexterity

Kelty-Stephen¹,

Lee

Carver

et al. 2020

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A growing consensus across otherwise disparate perspectives on perception and action is that visually guided postural control emerges from within task constraints. Task constraints generate physiological fluctuations across various parts of the body. These fluctuations foster exploration of the available sensory information. For instance, standard deviation (SD) and temporal correlations of bodily sway can indicate how richly postural control samples available mechanical and visual information. Too much or too little SD entails destabilization of posture. Temporal correlations show a similar relationship, but they have also been shown to support carrying sampled information to other aspects of the postural system. The present study shows that increasing visual constraints on posture reveals an adaptive relationship between SD and temporal correlations of postural fluctuations. In short, changing the viewing distance of a fixation target shows that temporal correlations self-correct themselves across time and diminish SD across time as well. Notably, these relationships were strong for all viewing distances except the most comfortable viewing and reaching distance. This self-correcting relationship allows the visual layout itself to press the postural system into a poise for engaging with objects and events in the surrounding.

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“…Ultimately, this task-and anatomically-specific portrait of multifractal fluctuations rests on the even more generic facts that multifractal fluctuations spread across the body and that estimates of this spread predict the accuracy of the perceptual outcomes [89,90]. Hence, rather than inventorying body parts and task constraints prompting different values of multifractality, the longer view of investigating visually-guided aiming must examine the flow of multifractal fluctuations.…”

Section: The Value Of Multifractality Is Also Specific To Different Tmentioning

confidence: 99%

Multifractality in postural sway supports quiet eye training in aiming tasks: A study of golf putting

Jacobson¹,

Berleman-Paul²,

Mangalam

et al. 2020

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The 'quiet eye' (QE) approach to visually-guided aiming behavior invests fully in perceptual information's potential to organize coordinated action. Sports psychologists refer to QE as the stillness of the eyes during aiming tasks and increasingly into self- and externally-paced tasks. Amidst the 'noisy' fluctuations of the athlete's body, quiet eyes might leave fewer saccadic interruptions to the coupling between postural sway and optic flow. Multifractality in postural sway is a robust predictor of both visual and haptic perceptual responses. Postural sway generates optic flow centered on an individual's eye height. So, we manipulated the eye height part way through a golf-putting task for participants trained in QE or trained technically as per conventional golf putting. We predicted that perturbing the eye height by attaching wooden blocks below the feet would perturb the putting more so in QE-trained participants than in those trained technically. We also predicted that responses to this perturbation would depend on multifractality in postural sway. Specifically, we predicted that less multifractality would predict more adaptive responses to the perturbation and higher putting accuracy. Results supported both predictions. QE training and lower multifractality led to more frequent successful putts, and the perturbation of eye height led to less frequent successful putts, particularly for QE-trained participants. Models of radial error (i.e., the distance between the ball's final position and the hole) indicated that lower estimates of multifractality due to nonlinearity coincided with a more adaptive response to the perturbation. These results challenge the past suggestions that reduced multifractality might be a signature of diseased posture. Instead, they suggest that reduced multifractality may act in a context-sensitive manner to restrain motoric degrees of freedom to achieve the task goal.

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Global broadcasting of local fractal fluctuations in a bodywide distributed system supports perception via effortful touch

Cited by 32 publications

References 74 publications

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

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

Multifractal roots of suprapostural dexterity

Multifractality in postural sway supports quiet eye training in aiming tasks: A study of golf putting

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