Masticatory movement was investigated by using the simple motion-picture method for 125 subjects consisted of four groups, 1) 38 young adult males (aged 19-29 years), 2) 45 young adult females (aged 19-29 years), 3) 24 adult males (aged 40-59 years) and 4) 18 adult females (aged 40-59 years). Test foods consisted of hard jelly and boiled carrot having four different size. Duration and frequency of mastication were counted by observation of the picture which had recorded the eating subjects on video tape. The results were as follows.
1. Mean chewing frequencies obtained by counting the number of masticatory cycle for hard jelly was significantly large than that of carrot. The mean rate of masticatory cycle of hard jelly also significantly slow than that of carrot.
2. Decreasing the carrot in size caused increase in masticatory frequencies and decrease in the rate of masticatory cycle.
3. The group of young adult male showed significantly smaller frequencies and more quickly cycle for mastication of hard jelly than the young adult female group.
4. The rate of masticatory cycle of the small size carrot showed significantly difference among male and female.
5. Correlation between the masticatory movement and sensation of hardness was not appeared.