title: Haptic feedback attenuates illusory bias in pantomime-grasping: evidence for a visuo-haptic calibration.
abstract: Relative visual information has been shown to mediate grasping responses directed to an area previously occupied by a target object (i.e., pantomime-grasping) and is an information type functionally distinct from the absolute visual information supporting naturalistic grasping (i.e., grasping a physical target). Pantomime- and naturalistic grasps differ not only in terms of their visual properties, but also because the former lacks physical interaction with a target object (i.e., no-haptic feedback). The absence of haptic feedback may represent a reason why pantomime- and naturalistic grasps differ. To address this issue, participants completed pantomime-grasps to objects embedded in fins-in and fins-out configurations of the Müller-Lyer (ML) illusion following a 2000-ms visual delay when haptic feedback was unavailable (H- condition), and when experimentally induced (H+ condition). In particular, in the H+ condition the experimenter placed a physical target object between participants' thumb and forefinger after they completed their grasping response. H- and H+ conditions were performed when online vision was available (i.e., Experiment 1) and when withdrawn (i.e., Experiment 2). If haptic feedback influences grasping, then the absolute information afforded from physically touching a target object (i.e., the H+ condition) should result in aperture metrics that are refractory-or attenuated-to the relative properties of the ML figures. Grip apertures in H- and H+ conditions were "tricked" in a direction consistent with the perceptual effects of the ML illusion; however, Experiment 2 showed that illusory effects were attenuated in the H+ condition. In other words, responses without online vision showed evidence of a visuo-haptic calibration. These results provide convergent evidence that haptic and visual feedback play a salient role in considering the extant literature's documented report of kinematic differences between pantomime- and naturalistic grasps.
authors.affiliation: School of Kinesiology, The University of Western Ontario, London, ON, N6A 3K7, Canada.
authors.forename: Jillian
authors.initials: J
authors.lastname: Chan
authors.affiliation: School of Kinesiology, The University of Western Ontario, London, ON, N6A 3K7, Canada. mheath2@uwo.ca.|Graduate Program in Neuroscience, The University of Western Ontario, London, ON, Canada. mheath2@uwo.ca.
authors.forename: Matthew
authors.initials: M
authors.lastname: Heath
mesh_terms: D000704:Analysis of Variance; D015982:Bias; D001696:Biomechanical Phenomena; D002138:Calibration; D056228:Feedback, Sensory / Q000502:physiology*; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D007088:Illusions / Q000502:physiology*; D008297:Male; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D055815:Young Adult
keywords: Grasping; Haptic feedback; Müller–Lyer figures; Pantomime; Visuomotor