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Noura Alomawi, Joost C. Dessing, Xiaogang Yan, J. Douglas Crawford; Influence of Visual Feedback on Gaze-Dependent and Location-Dependent Errors in Grasp Location and Orientation. Journal of Vision 2014;14(10):411. doi: https://doi.org/10.1167/14.10.411.
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Previous studies have shown that visual feedback from the target and the hand is important to plan, guide, and enhance the accuracy of pointing and reaching movement (e.g. Berkinblint et al. 1995; Blohm et al. 2007). A recent study showed that providing visual feedback about the hand supresses gaze dependent errors (Dessing et al. 2012). In a previous report (AlOmawi et al. 2013) we used a reach to grasp task that involves precision grip and hand orientation during open loop condition to investigate the influence of gaze and target positions on the transport and orientation components of the hand. This paradigm utilized rectangular 'virtual' targets presented at 3 orientations, 3 locations, and with 3 gaze fixation positions. Here we altered this paradigm to investigate the influence of visual feedback (VF) from the target, hand, or both on gaze- and location- dependents errors. Seven subjects reached to grasp the target during four VF conditions; brief target presentation with no further feedback (No VF), prolonged vision of the target (Target VF), the prolonged vision of the hand (Hand VF), or both (Full VF), all semi randomized within the testing blocks. We found that reach location errors related to gaze and target location were highly correlated for all subjects (0.622 <0.96, P <.001) between the No VF and Target VF, whereas, Full VF errors correlated to Hand VF errors (0.472 <0.99, P<.001). Hand VF increased the variability of reach location errors, while Target VF reduced the variability. However, the modulation of Hand and Target VF was dependent on the direction of the reach stimulus and gaze. In contrast, there was no influence of VF in grasp orientation errors. Our results suggest that grasp location and orientation are controlled separately, and are differentially influenced by hand position and target feedback, respectively.
Meeting abstract presented at VSS 2014
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