Hearing investigations were conducted for kindergarteners aged 3 to 6 to study their perceptions of images observed through a telescope. Three surveys provided us with voice samples from 149 kindergarten children. Children’s perceptions of objects observed through a telescope increased not only with age but with object type and their perceptions of image inversion and magnification also improved with age and object type. The inversion of an image of a popular animation character was recognized by 56% of younger children and 95% of older children, whereas the inversion of the lunar images was recognized by only 52% of older children. Our results show that a perception gap regarding images observed through a telescope exists among children aged around 4–5 years old.

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The present study was designed to investigate the development of a rapidly repeating movement of the whole body from ground reaction forces exerted during a side jump. Subjects were 246 healthy males aged 5-17 years, and their physique (body height, body mass,skinfold thickness) , muscular power (vertical jump, standing broad jump) and rapidly repeating movement (stepping, side jump) were measured. The procedure of the side jump were hopping between two parallel lines on the force plate from right to left alternately as quickly as possible. The distance between the lines was fixed at one third of the mean body height at each age. Force curves gained by using force plate were calculated using the jumping frequency per 1 second (the frequency calculated from the time required for one jump), the times on the ground and in the air, the maximum vertical and horizontal forces, the vertical and horizontal impulses and the kicking angle caluculated from maximum vertical and horizontal forces. The frequency of the side jump per 1 second increased significantly with age by 11 years. The time on the ground shortend significantly with age by 10 years. The time in the air shortened significantly with age by 7 years. The maximum vertical force per unit body mass did not change remarkably with age, but the maximum horizontal force per unit body mass increased significantly with age by 12 years. The kicking angle decreased significantly with age by 12 years. The vertical impulse per unit body mass decreased significantly with age by 11 years, but the horizontal impulse per unit body mass did not change remarkably with age. These results suggest that a rapid repeating ability of the whole body develops by increasing the horizontal force in compairison with vertical force and by decreasing the kicking angle and the vertical displacement of the center of gravity with age by about 12 years.

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