title: Distinct visual cues mediate aperture shaping for grasping and pantomime-grasping tasks.
abstract: The authors examined whether the top-down requirements of dissociating the spatial relations between stimulus and response in a goal-directed grasping task renders the mediation of aperture trajectories via relative visual information. To address that issue, participants grasped differently sized target objects (i.e., grasping condition) and also grasped to a location that was dissociated from the target object (i.e., pantomime-grasping condition). Just noticeable difference (JND) values associated with the early through late stages of aperture shaping were computed to examine the extent to which motor output adhered to, or violated, the psychophysical principles of Weber's law. As expected, JNDs during the late stages of the grasping condition violated Weber's law: a result evincing the use of absolute visual information. In contrast, JNDs for the pantomime-grasping condition produced a continuous adherence to Weber's law. Such a result indicates that dissociating a stimulus from a response is a perception-based task and results in aperture shaping via relative visual information.
authors: School of Kinesiology, The University of Western Ontario, London.
authors: Scott A
authors: SA
authors: Holmes
authors: Jennifer
authors: J
authors: Lohmus
authors: Shelby
authors: S
authors: McKinnon
authors: Ali
authors: A
authors: Mulla
authors: Matthew
authors: M
authors: Heath
mesh_terms: D000293:Adolescent; D000465:Algorithms; D003463:Cues; D003627:Data Interpretation, Statistical; D004056:Differential Threshold / Q000502:physiology; D005260:Female; D005868:Gestures; D006040:Goals; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011601:Psychophysics; D013028:Space Perception; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult