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

J Physiol. 2024 Mar 28. doi: 10.1113/JP286027. Online ahead of print.ABSTRACTWhen 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, mea...

Source: The Journal of Physiology - March 28, 2024 Category: Physiology Authors: Naqash Afzal Sophie du Bois de Dunilac Alastair J Loutit Helen O Shea Pablo Martinez Ulloa Heba Khamis Richard M Vickery Micha ël Wiertlewski Stephen J Redmond Ingvars Birznieks Source Type: research