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Valentin Crainic, John de Grosbois, Tifanny Lung, Arindam Bhattacharjee, Luc Tremblay; Limb-target regulation processes: Further evidence for a sweet spot.. Journal of Vision 2014;14(10):415. doi: 10.1167/14.10.415.
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Recently, we proposed that limb-target regulation processes are primarily based on visual feedback that is available when the limb travels between 1.0 and 1.1 m/s (Tremblay et al. 2013a). We have also observed that perceptual judgments of endpoint accuracy are better when a brief visual window (20 ms) is provided when the limb travels at 1.0 m/s, compared to faster and slower limb velocity criteria (Tremblay et al. 2013b). In this study, we implemented a target jump procedure. We reasoned that if limb-target regulation processes are more likely to take place at limb velocities neighbouring 1.0 m/s, then participants should more effectively amend their trajectory to a target jump presented at 1.0 m/s, compared to other limb velocities. Thirteen participants were asked to maintain their gaze on their finger until a go signal (target and brief tone, presented for 20 ms), which prompted them to perform a reaching movement as accurately as possible while maintaining a 325-375 ms movement time bandwidth. Participants performed 20 control trials with vision throughout the movement (full vision). In addition, they performed reaching movements with 20 ms of vision combining 3 limb velocity conditions (0.6, 1.0, 1.4 m/s: before peak velocity) with 2 target conditions (no-jump: 30 cm, jump: 27 cm). Participants performed 30 trials under each velocity condition while the target jump occurred on 10 of these 30 trials. By contrasting the no-jump and jump trials separately for each velocity condition, we observed that participants exhibited longer movement times, longer times spent in the deceleration phase, and shorter reaching amplitudes with the 1.0 m/s condition only. Therefore, we provide further evidence for the predominance of limb-target regulation processes when the limb velocity reaches 1.0 m/s (or the corresponding time or position of the trajectory) compared to other limb velocities.
Meeting abstract presented at VSS 2014
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