Right-front Direction in Parabolic Flight

The goal of this study is to objectively determine the perceived direction of the right-front by the subjects in weightlessness. The direction of the right-front has not been investigated to date with the measurements of the position of the eyes. The investigators will compare the intersection of the horizontal and vertical saccadic trajectories (jerky) with the apparent direction of the right-front indicated by the subjects when they look right front in the dark (LOOK) and that they indicate when they determine whether a visual target through the right-front apparent (PERCEPTION). Then, the investigators will compare these measurements between normal gravity and microgravity hypergravity during parabolic flight.