Abstract

It was investigated whether the perceived size of biological motion differs depending on the walking direction, approaching or away. In experiment 1a, the stimulus used for the size determination task was a point-light walker that added shaded information that could emphasize the perception of an object approaching or moving away. It was found that the stimulus was perceived larger in the approaching direction than in the away direction. In Experiment 1b, the difference in size perception depending on the walking direction was reaffirmed when the order of reference and test stimulus presentation were counterbalanced. Especially, this difference in size perception was observed under conditions in which the stimulus was presented at a relatively long period of time (1000 ms). In Experiment 2, it was investigated whether an implied approaching motion in a single frame image could cause a difference in size perception, and it was confirmed. This suggests that size perception can be influenced by the representation of the implied motion. This study shows that the sociobiological value of walking direction can influence the size of the object represented by the biological motion to be perceived differently, suggesting that this effect may have occurred at the level of motion representation rather than the level of perception of physical motion.