Abstract
Vection is dominated by retinal image motion of the static external scene. If object motion is perceived, rather than environment motion, vection is not strongly induced. Previous research has indeed suggested that the allocation of motion to the object can typically occur for meaningful stimuli, such as feathers, petals or leaves, which cannot induce stronger vection. However, still few studies have focused on this relationship between stimulus meaning and vection. The present study examined how and whether stimulus meaning influences vection by using more informative meaningful animations. In Experiment 1, we presented 9 movies to the participants consisting of two lines of cars (with or without wheel rotations) that moved forward, backward, or upward. Each movie lasted for 30 seconds. We also presented inverted cars and black ovals that moved forward as control conditions. In Experiment 2, we further investigated the effect of the meaning of the background added to the moving cars. We presented 6 movies consisting of two lines of cars that moved forward with a static background or a moving background in the same or opposite direction. Participants were required to press the button if they were perceiving vection and rated the subjective vection strength by using a 101-point rating scale. The results of Experiment 1 showed that in conditions with forward- and backward-moving cars, vection was stronger than in conditions with upward-moving and inverted cars. The results of Experiment 2 showed that vection became the weakest in the static background condition and that the cars’ wheel rotations could facilitate vection. We thought that the more natural the stimulus meanings were (forward- and backward-moving cars), the stronger the vection was, following the “naturalness-hypothesis” (Nakamura, 2013). The relationship between the effects of stimulus meaning and naturalness on vection should be further examined in the future.