On-line utilization of visual and proprioceptive information during manual aiming

Luc Tremblay, University of Toronto

Abstract
Movement endpoint accuracy requires extensive use of sensory information during movement execution. Interestingly, studies on the on-line control of goal-directed movements focused primarily on visual information (see Elliott, et al., 2001; cf. Adams et al., 1977) and assumed that effects of visual feedback withdrawal on endpoint accuracy merely reflect its importance (e.g., Proteau et al., 1987). In this study, the hypothesis that visual feedback withdrawal alters proprioceptive information utilization was tested. Sixteen participants completed 20 discrete aiming movements (25 cm) in each of the sixteen conditions: 2 Vision (Full, No) X 3 Tendon Vibration (Triceps, Biceps, None) X 3 Galvanic Vestibular Stimulation (Left, Right, Neutral). Conditions were presented in a random order and triggered at movement initiation. The dependent variables were Constant Error (CE) and Variable Error (VE) for movement extent and direction. As expected, vision availability significantly affected aiming accuracy. Interestingly, there were significant interactions between Vision and Tendon Vibration for CE and VE in movement direction. Finally, there was an interaction involving all factors for CE in movement direction. These results support the hypothesis that proprioceptive information utilization is affected by visual feedback availability and that such interaction is also present between sources of proprioceptive information.

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