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Role of arm reaching movement kinematics in friction perception at initial contact with smooth surfaces

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posted on 2024-05-13, 11:28 authored by Naqash Afzal, Sophie du Bois de Dunilac, Alastair J. Loutit, Helen O'SheaHelen O'Shea, Pablo Martinez Ulloa, Heba Khamis, Richard M. Vickery, Michaël Wiertlewski, Stephen J. Redmond, Ingvars Birznieks

When manipulating objects, humans begin adjusting their grip force to friction within 100 ms of contact. During motor adaptation, subjects become aware of the slipperiness of touched surfaces. Previously, we have demonstrated that humans cannot perceive frictional differences when surfaces are brought in contact with an immobilised finger, but can do so when there is submillimeter lateral displacement or subjects actively make the contact movement. Similarly, in, we investigated how humans perceive friction in the absence of intentional exploratory sliding or rubbing movements, to mimic object manipulation interactions. We used a two-alternative forced-choice paradigm in which subjects had to reach and touch one surface followed by another, and then indicate which felt more slippery. Subjects correctly identified the more slippery surface in 87 ± 8% of cases (mean ± SD; n = 12). Biomechanical analysis of finger pad skin displacement patterns revealed the presence of tiny (<1 mm) localised slips, known to be sufficient to perceive frictional differences. We tested whether these skin movements arise as a result of natural hand reaching kinematics. The task was repeated with the introduction of a hand support, eliminating the hand reaching movement and minimising fingertip movement deviations from a straight path. As a result, our subjects’ performance significantly declined (66 ± 12% correct, mean ± SD; n = 12), suggesting that unrestricted reaching movement kinematics and factors such as physiological tremor, play a crucial role in enhancing or enabling friction perception upon initial contact.

Funding

The secret of tiny hand movements to feel and manipulate objects

Australian Research Council

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The role of spike patterning in shaping human perception of tactile stimuli

Australian Research Council

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History

Publication

The Journal of Physiology, 2024, 602, pp. 2089-2106

Publisher

Wiley and Sons Ltd

Department or School

  • Psychology

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