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Karen Lau, Eric Roy, Genevieve Desmarais; Effects of experience and amount of visual feedback when pointing to visible and remembered targets. Journal of Vision 2008;8(6):49. doi: 10.1167/8.6.49.
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© ARVO (1962-2015); The Authors (2016-present)
Most studies involving pointing to present and remembered targets tend to report situations when both the limb and target are present (closed loop-target present), or when both the limb and target are occluded (open loop-target absent). This neglects conditions where only 1 of the above 2 variables is available. There may exist differences between these 2 variables so that unique information for a particular visual condition is utilized while pointing to targets in space. To address this, we asked young (N=10, mean age=22.9 years) right-handed participants to point to targets in a virtual aiming task. Six movements were performed to each of six targets while manipulating whether participants had vision of their pointing limb, the target, or both. In target-absent trials, the time between target occlusion and movement initiation were changed to examine mental target representation. To do so, there were 2 delay times: 0 and 2 seconds. To investigate the effect of experience, performance was also compared before and after a practice period. Half of the participants received open loop feedback first; the other half received closed loop feedback initially. Results indicate open loop aiming tasks are more dependent on the delay periods between target occlusion and movement onset. Only block effects (that is, before or after practice) affected closed loop results. This suggests the use of a time sensitive ([[lt]]2 seconds) stored visual representation of the environment available only when vision of the limb is absent. Implications of initial visual condition exposure and kinematic and accuracy differences between open and closed loop aiming conditions with the target present or absent will be discussed.
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