The Effects of Visual Parabolic Motion on the Subjective Vertical and on Interception

Observers typically present a strong bias in estimating the orientation of visual bar when their body is tilted >60° roll plane and absence background information. Known as A-effect, this phenomenon likely results from under-compensation tilt. Static cues can reduce such perceived vertical. Yet, it unknown whether dynamic would be also effective. Here we presented projectile motions target along parabolic trajectories with different orientations relative to physical gravity. The aim experiment was twofold: First, assessed could estimation bar, measured classical subjective vertical (SVV) task. Second, evaluated ability estimate time-to-contact an interception task influenced by these trajectories. Two groups participants performed experiment, either head 90° or upright position. We found that SVV affected This result but not participants. In task, timing error increased linearly function parabola. These support hypothesis gravity vector estimated stimuli contributes