2020 年 20 巻 p. 18-25
This study elucidates the developmental characteristics of orientation and differentiation abilities of jumping motion in early childhood. Therefore, we conducted the Moving Target Jump (MTJ) test to predict the target movement and jumping in a timely manner. The test was conducted twice per person. On examining the characteristics of changes on the basis of gender, age, and the number of trials, the following results were obtained. (1) With respect to the difference in the absolute value between the first and second tests, the absolute value in the second test was significantly smaller in the late three-year-old children, suggesting a learning effect due to the repetition of the task. (2) In the distribution of movement angles, a large variation was observed between the late three-year-old and the early four-year-old children; however, beyond the late four years of age, there was a tendency to gather around 360°, the reference value. (3) With respect to the gender characteristics, a study of the proportion of premature reaction (355° > movement angle) and delayed reaction (365° < movement angle) suggested that girls had a greater proportion of delayed reactions than boys. Hence, the development of orientation and differentiation abilities to predict the moving targets and time their landing and jumping in early childhood revealed different developmental tendencies between boys and girls, suggesting that the prediction of the moving target or the start of the jump motion tended to be delayed in girls. Additionally, it was suggested that the learning effect of the test task appeared in the late three-year-olds and that orientation and differentiation abilities necessary for the MTJ test were acquired in the late four-year-olds.