Interwoven fluctuations during intermodal perception: Fractality in head sway supports the use of visual feedback in haptic perceptual judgments by manual wielding.

2015

Ecological Psychology

Self Cite

Nesting is a major cornerstone in ecological theorizing about visual perception, through both nesting of surface layout in locomotory movements and nesting of visually available surfaces within each other, from focal to peripheral vision. This work sought to probe these nesting relationships by examining the effects of the visual periphery on the strength of interactions among nested time scales in head sway. That is, we tested whether spatial nesting of the focal within peripheral visual fields stimulated nonlinear interactions amid temporal nesting. We examined head sway during 2 variants of the Fitts task, one involving manual pointing by seated participants and another involving walking comfortably with upright standing posture. All participants completed both tasks but were randomly assigned to experience these tasks with or without the visual periphery available. Multifractal analysis of head sway revealed that visual availability of the periphery promoted nonlinear interactions across nested time scales, but this effect depended on how much head sway extended across a plane than more ballistically along a single axis of variability.

Section: Nesting Of Surfaces In the Visual Fieldmentioning

confidence: 99%

mentioning

confidence: 99%

Nesting of Focal Within Peripheral Vision Promotes Interactions Across Nested Time Scales in Head Sway: Multifractal Evidence From Accelerometry During Manual and Walking-Based Fitts Tasks

Eddy

2015

Ecological Psychology

Self Cite

“…The present results indicate that self-organization need not generate veridical responses. Self-organization may be an important framework in which to consider learning in general (Kelty- Stephen & Dixon, 2014;Spencer, Thomas, & McClelland, 2009;Thelen & Smith, 1994), but we should not forget that some of the most pioneering and programmatic work in applying self-organization to psychology dealt with a perceptual discrepancy, namely, the Piagetian A-not-B error in which the developing infant's mind systematically misaligns haptic coordination of infant reaching with visual information about target location, leading to a systematically non-zero discrepancy between reach and target (e.g., Clearfield, Dineva, Smith, Diedrich, & Thelen, 2009;Spencer, Dineva, & Smith, 2009;Spencer, Perone, & Buss, 2011). Individual participants' perceptual-discrepancy data in Interleaved group (black) compared to predicted perceptual discrepancy according to Model 2 (shown in Table 3; grey) for all judgments that they produced.…”

Section: Discussionmentioning

confidence: 99%

Self-trained perception need not be veridical: striking can exaggerate judgment by wielding and can transfer exaggeration to new stimuli

Atten Percept Psychophys

Eddy

2015

Self Cite

Previous literature on self-training dynamic touch suggested that haptic judgments of length following wielding might benefit from new information through participants' own striking actions with the same stimuli. However, the conclusion that this self-training tended towards a veridical outcome of zero discrepancy between actual length and judged length was premature. In this replication, we allowed adult participants (n = 15) to strike on each trial and changed the stimuli in mid-experiment to determine whether striking helped participants build more accurate perceptions of length transferrable from one stimulus scale to another. We predicted that, if selftraining led to better length judgments, the repeated striking would improve judgments and that, in turn, judgments following the switch of stimuli would show a good transfer of what participants had learned. On the other hand, self-training may simply exaggerate inertial properties of stimuli and may be sensitive to sudden changes in the scale of stimuli. Mixedeffect modeling of discrepancies show that striking only accentuated effects of inertial moment, producing exaggerated length judgments. Correlation between perceived length and actual length increased only for participants who experienced a switch in individual stimuli but not stimulus scale. We discuss the implications of these findings for any theoretical relationship between self-organization and veridicality.

“…of exploratory movements across the body [e.g., in hand, foot, head and postural center of pressure (henceforth, CoP)] all support the use of available mechanical information for generating perceptual judgments via dynamic touch [21][22][23][24][25][26]. The predictive role of fractal fluctuations appears to even extend across the body.…”

Section: Modulating the Bodywide Flow Of Mechanical Fluctuations To Imentioning

confidence: 94%

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

Mangalam

Carver²,

2020

Preprint

Self Cite

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...