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Gavin P. Lawrence, Michael A. Khan, Stuart Mourton and Pierre-Michel Bernier

The objective of the current study was to determine whether the reliance on visual feedback that develops with practice is to due utilizing vision to adjust trajectories during movement execution (i.e., online) and/or to enhance the programming of subsequent trials (i.e., offline). Participants performed a directional aiming task with either vision during the movement, dynamic feedback of the trajectory of the movement or the movement endpoint. The full vision condition was more accurate during practice than the other feedback conditions but suffered a greater decrement in performance when feedback was removed. In addition, the reliance on trajectory feedback was greater compared with the endpoint feedback. It appears that the reliance on visual feedback that develops with practice was due to both online and offline processing.

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Jeremy W. Noble, Janice J. Eng and Lara A. Boyd

This study examined the effect of visual feedback and force level on the neural mechanisms responsible for the performance of a motor task. We used a voxelwise fMRI approach to determine the effect of visual feedback (with and without) during a grip force task at 35% and 70% of maximum voluntary contraction. Two areas (contralateral rostral premotor cortex and putamen) displayed an interaction between force and feedback conditions. When the main effect of feedback condition was analyzed, higher activation when visual feedback was available was found in 22 of the 24 active brain areas, while the two other regions (contralateral lingual gyrus and ipsilateral precuneus) showed greater levels of activity when no visual feedback was available. The results suggest that there is a potentially confounding influence of visual feedback on brain activation during a motor task, and for some regions, this is dependent on the level of force applied.

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Michael A. Khan, Gavin P. Lawrence, Ian M. Franks and Digby Elliott

The purpose of the present study was to establish the contribution of visual feedback in the correction of errors during movement execution (i.e., online) and the utilization of visual feedback from a completed movement in the programming of upcoming trials (i.e., offline). Participants performed 2 dimensional sweeping movements on a digitizing tablet through 1 of 3 targets, which were represented on a video monitor. The movements were performed with and without visual feedback under 4 criterion movement times (150, 250, 350, 450 msec). We analyzed the variability in directional error at 25%, 50%, 75%, and 100% of the distance between the home position and the target. There were significant differences in variability between visual conditions at each movement time. However, in the 150-msec condition, the form of the variability profiles did not differ between visual conditions, suggesting that the contribution of visual feedback was due to offline processes. In the 250-, 350-, and 450-msec conditions, there was evidence for both online and offline control, as the form of the variability profiles differed between the vision and no vision conditions.

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Jeff E. Goodwin

Participants were randomly assigned to one of four groups. The fade group received 100% concurrent visual feedback on acquisition trials 1–4, 75% on trials 5–8 (concurrent feedback on trials 5, 6, and 7), 50% on trials 9–12 (concurrent feedback on trials 10 and 12), 25% on trials 13–16 (concurrent feedback on

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Marcie Fyock, Nelson Cortes, Alex Hulse and Joel Martin

investigating real-time visual feedback as an intervention choice for the treatment of PFP in adult recreational runners. Focused Clinical Question In adult runners diagnosed with PFP, does gait retraining with real-time visual feedback lead to a decrease in pain? Summary of Search, “Best Evidence” Appraised

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Patrice R. Rougier and Samir Boudrahem

Past studies have emphasized the beneficial effect of additional visual feedback (VFB) on the capacity of healthy adults to decrease the amplitudes of the center-of-pressure minus center-of-gravity (CP-CGv) movements. To better assess these capacities, 56 subjects were asked to stand still on a force platform and to use the visual information provided. Dependency coefficients, based on their capacity to lower their CP-CGv movements and therefore relax their lower limb muscles, as well as parameters aimed at characterizing their postural strategies were measured across VFB conditions including (1) CP displacements in real time (VFBCP0), (2) CP displacements with a 600-ms delay (VFBCP600), and (3) CP-CGv displacements with a 600-ms delay (VFBCP-CG600). A non-VFB condition (eyes open) was also included. Several linear correlations were used to specify the relation between subjects’ capacity to relax, compared with the VFBCP0 condition, across the three remaining conditions. The data highlight the complementary nature of the VFB conditions and establish the postural control behaviors necessary to use these VFB protocols efficiently.

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Marlene Luis and Luc Tremblay

We aimed to determine if visual feedback use during aerial skills is more efficient at low angular head velocity (AHV; i.e., <350 deg/s) than at high AHV. Twelve experienced female acrobats performed 20 back tuck somersaults under four experimental conditions: full-vision (FV), vision at AHV below 350 deg/s (VBelow), vision at AHV above 350 deg/s (VAbove), and no-vision (NV). AHV was calculated in real time, and liquid crystal goggles were used to manipulate vision. Two gymnastics judges scored landing stability using a four-point scale. All vision conditions that allowed some vision yielded significantly better landing scores than in the NV condition. Furthermore, a nonparametric test revealed that VBelow yielded a better performance ranking than the FV condition. We conclude that visual feedback during a back tuck somersault is used for landing stability at all angular head velocities, but optimal feedback use occurs when there is retinal stability.

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Christina Olbrantz, Jamie Bergelin, Jill Asmus, Thomas Kernozek, Drew Rutherford and Naghmeh Gheidi

performance-based feedback is frequently attempted to alter movements such as drop landings that increase the risk of PFP. 1 , 10 A recent review on various forms of movement-based feedback concluded that a combination of verbal and visual feedback may have the greatest effect on reducing GRF during a drop

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Gabriel Andrade Paz, Lohanne Almeida, Larissa Ruiz, Sabrina Casseres, Giovanna Xavier, João Lucas, Haroldo Gualter Santana, Humberto Miranda, Scott Bonnette and Jeffrey Willardson

that can deliver feedback independent of an expert. The feedback system provides visual feedback from a laser sensor (VFLS), and it has been implemented with the purpose to guide joint movement and enhance the acquisition of proper motor patterns. Although it has been shown that directing one

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Job Fransen, Thomas W.J. Lovell, Kyle J.M. Bennett, Dieter Deprez, Frederik J.A. Deconinck, Matthieu Lenoir and Aaron J. Coutts

The aim of the current study was to examine the influence of restricted visual feedback using stroboscopic eyewear on the dribbling performance of youth soccer players. Three dribble test conditions were used in a within-subjects design to measure the effect of restricted visual feedback on soccer dribbling performance in 189 youth soccer players (age: 10–18 y) classified as fast, average or slow dribblers. The results showed that limiting visual feedback increased dribble test times across all abilities. Furthermore, the largest performance decrement between stroboscopic and full vision conditions was in fast dribblers, showing that fast dribblers were most affected by reduced visual information. This may be due to a greater dependency on visual feedback at increased speeds, which may limit the ability to maintain continuous control of the ball. These findings may have important implications for the development of soccer dribbling ability.