Abstract
This study investigated developmental changes in choices of action, particularly with regard to participants' leg length. Each of 128 children and 18 adult participants was asked to walk beyond a rope by either stepping over it or passing under it. The rope height was changed up and down from a point half of each participant's height. The highest rope height over which a participant stepped was called one's 'transition point.' Additionally, we called the highest stepping-over rope for which individuals did not touch the rope the 'success point.' Dividing each of these heights by the person's leg length, we calculated a 'transition ratio' and a 'success ratio.' The transition ratio and success ratio value became almost equal after age 7. The transition ratio value of males was higher than that of females. It follows from these results that stepping-over or passing-under was chosen based on the relation between leg length and the rope height. Humans apparently gain such a perception at age 6 or 7. The discussion also considered that 4-6-year old children can perceive their leg length and physical ability, and that the lower transition ratio of females is related to their avoidance of the risk of falling down.
