title: Touch uses frictional cues to discriminate flat materials.
abstract: In a forced-choice task, we asked human participants to discriminate by touch alone glass plates from transparent polymethyl methacrylate (PMMA) plastic plates. While the surfaces were flat and did not exhibit geometric features beyond a few tens of nanometres, the materials differed by their molecular structures. They produced similar coefficients of friction and thermal effects were controlled. Most participants performed well above chance and participants with dry fingers discriminated the materials especially well. Current models of tactile surface perception appeal to surface topography and cannot explain our results. A correlation analysis between detailed measurements of the interfacial forces and discrimination performance suggested that the perceptual task depended on the transitory contact phase leading to full slip. This result demonstrates that differences in interfacial mechanics between the finger and a material can be sensed by touch and that the evanescent mechanics that take place before the onset of steady slip have perceptual value.
authors.affiliation: Institute of Neuroscience, Université catholique de Louvain, B-1200, Brussels, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Gueorguiev
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 7222, ISIR, F-75005, Paris, France.
authors.forename: Séréna
authors.initials: S
authors.lastname: Bochereau
authors.affiliation: Institute of Neuroscience, Université catholique de Louvain, B-1200, Brussels, Belgium.
authors.forename: André
authors.initials: A
authors.lastname: Mouraux
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 7222, ISIR, F-75005, Paris, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Hayward
authors.affiliation: Institute of Neuroscience, Université catholique de Louvain, B-1200, Brussels, Belgium.|Cliniques Universitaires Saint-Luc, Physical and Rehabilitation Medicine Department, Université catholique de Louvain, B-1200, Brussels, Belgium.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Thonnard