title: The spatial relations between stimulus and response determine an absolute visuo-haptic calibration in pantomime-grasping.
abstract: Pantomime-grasps entail a response to an area adjacent to (i.e., spatially dissociated pantomime-grasp), or previously occupied by (i.e., no-target pantomime-grasp) a target. Previous work has reported that pantomime-grasps differ kinematically from naturalistic grasps (i.e., grasping a physical target object) - a result taken to evince that pantomime-grasps are perception-based and mediated via relative visual information. However, such actions differ not only in terms of their visual properties, but also because the former precludes haptic feedback related to a target's absolute size. The current study provides four experiments examining whether experimenter-induced haptic feedback influences the information mediating spatially dissociated and no-target pantomime-grasps. Just-noticeable-difference scores were computed to determine whether grasps adhered to, or violated, the relative psychophysical properties of Weber's law. Spatially dissociated pantomime-grasps performed with haptic feedback adhered to Weber's law (Experiments 1-3), whereas their no-target pantomime-grasp counterparts violated the law (Experiment 4). Accordingly, we propose that the top-down demands of decoupling stimulus-response relations in spatially dissociated pantomime-grasping renders aperture shaping via a visual percept that is not directly influenced by the integration of haptic feedback. In turn, the decreased top-down demands of no-target pantomime-grasps allows haptic feedback to serve as a reliable sensory resource supporting an absolute visuo-haptic calibration.
authors.affiliation: School of Kinesiology, University of Western Ontario, Canada.
authors.forename: Shirin
authors.initials: S
authors.lastname: Davarpanah Jazi
authors.affiliation: School of Kinesiology, University of Western Ontario, Canada; Graduate Program in Neuroscience, University of Western Ontario, Canada. Electronic address: mheath2@uwo.ca.
authors.forename: Matthew
authors.initials: M
authors.lastname: Heath
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D004056:Differential Threshold; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D000072458:Orientation, Spatial / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D055815:Young Adult
keywords: Allocentric; Egocentric; Grasping; Haptic feedback; Pantomime; Weber’s law