The influence of advance information about target location and visual feedback on movement planning and execution.
ABSTRACT This study was designed to determine if movement planning strategies incorporating the use of visual feedback during manual aiming are specific to individual movements. Advance information about target location and visual context was manipulated using precues. Participants exhibited a shorter reaction time and a longer movement time when they were certain of the target location and that vision would be available. The longer movement time was associated with greater time after peak velocity. Under conditions of uncertainty, participants prepared for the worst-case scenario. That is, they spent more time organizing their movements and produced trajectories that would be expected from greater open-loop control. Our results are consistent with hierarchical movement planning in which knowledge of the movement goal is an essential ingredient of visual feedback utilization.
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ABSTRACT: This study examined if, and how, implicit advance knowledge of upcoming ball speed influences the interplay between arm movements and concomitant postural adjustments in one-handed catching. While standing, subjects were asked to catch balls that were presented with or without implicit advance knowledge of four different ball speeds. Full body kinematics and ground reaction forces were measured, which allowed the assessment of arm movements and postural adjustments through the momentum of the arm, rest of the body and whole body. Providing implicit advance knowledge induced a forward arm raising movement scaled to ball speed in the initial transport phase. However, the accompanying backward postural adjustments were unaffected, which is suggestive of a passive control mechanism. In the subsequent grasping phase, the scaling of arm raising movement exhibited in the presence of implicit advance knowledge resulted in a reduced need for postural adjustments, particularly at the highest ball speed. Together, these findings suggest that cortical involvement based on previous experience not only shapes the arm movements but also the subsequent interplaying postural responses.Neuroscience Letters 05/2012; 518(2):117-21. · 2.03 Impact Factor
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ABSTRACT: The online visual control of movement involves contributions from 2 processes: a process early in the trajectory concerned with comparisons between actual and expected sensory consequences and another process late in the trajectory that reduces the discrepancy between the position of the hand and the target. This experiment was designed to determine how early and late visual controls are impacted by the illusory characteristics of the target in a rapid reaching task. Participants performed 500 ms movements to the vertices of Müller-Lyer figures with the availability of full vision on the majority of trials. However, on a fraction of the trials, movements to the targets were performed with either early vision (first 200 ms of movement), late vision (last 200 ms of movement) or no vision. Although participants undershoot the targets under all target and visual conditions, the impact of the target configuration was greatest when vision was available during only the final portion of the movement trajectory and least when only early vision was available for limb regulation. Aiming bias under full-vision and no-vision conditions was intermediate. These findings indicate that visual context has a greater impact on late discrete limb regulation than on early dynamic control of the limb trajectory.Experimental Brain Research 06/2013; · 2.22 Impact Factor
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ABSTRACT: ABSTRACT Recently, D. Elliott et al. (2010) asserted that the current control phase of a movement could be segregated in multiple processes, including impulse and limb-target regulation processes. The authors aimed to provide further empirical evidence and determine some of the constraints that govern these visuomotor processes. In 2 experiments, vision was presented or withdrawn when limb velocity was above or below selected velocity criteria. The authors observed that vision provided between 0.8 and 0.9 m/s significantly improved impulse regulation processes while vision provided up to 1.1 m/s significantly increased limb-target regulation processes. These results lend support to D. Elliott et al. and provide evidence that impulse regulation and limb-target regulation can take place at different velocities during a movement.Journal of Motor Behavior 02/2013; · 1.04 Impact Factor