Gaze Stability of Visually Trained and Non-Visually Trained Athletes During a Sport-Like Postural Task

Abstract

During object tracking, reflexive eye movements away from the target object or directional errors occur in order to capture visual field information. These ‘off-target’ visual data aid the brain in determining the velocity, location, and orientation of the objects in motion. However, an excessive amount of movement is classified as pro-saccade errors and can disrupt gaze stability. Little is known about how these errors differentiate between athletes who participate in object tracking sports versus those that do not in object tracking sports. PURPOSE: The aim of this study was to compare gaze stability of athletes who train and perform in visually (VT) and non-visually (NVT) rich environments during a sport-like postural anti-saccade task, the Wii Fit Soccer Heading Game (WFS). METHODS: 12 NCAA Division I VT (17.91 ± 0.51 years of age) and 12 matched (NVT) athletes (18.08 ± 0.51 years of age) wore a monocular eye tracker (240 Hz) while participating in two WFS trials of approximately 60 s. Athletes were instructed to maintain their gaze on the center of the screen during play. Motion capture was synced during the postural task to determine instantaneous gaze coordinates. Multivariate ANOVAs assessed gaze by direction (horizontal and vertical) for excursion and peak velocity, while an independent t-test assessed pro-saccade errors. RESULTS: A significant group difference was observed in vertical gaze (p<.05). Follow up assessments indicated greater gaze excursions (VT = 871.74 ± 446.23 pixels; NVT = 554.79 ± 220.54 pixels; p=0.038) and vertical peak velocities (VT = 1660.25 ± 860.78 pixels/s; NVT = 711.01 ± 551.45 pixels/s; p=0.004). No significant differences were observed in the horizontal direction. There were no significant differences in pro-saccade errors between the groups (p=0.96; VT SE=2.64; NVT SE=1.63). CONCLUSION: These results suggest that VT athletes’ gaze moved more and had greater velocity in the vertical direction when compared to NVT. This could indicate that VT use a vertical scanning visual strategy to locate and determine velocity of the object during a sport-like anti-saccade postural task. This could suggest that VT use different motor control strategies to maintain gaze stability during anti-saccade task than NVT.