Abstract
This study attempted to classify the normal hand movement patterns frequently seen during handling objects. Five normal subjects, ranging in age from 20 to 45 years, handled 93 objects one at a time in the predetermined situations. The movements of the hands and their projected images in the mirror were recorded using 16mm movie film at the rate of 32 times per second. Slow projection of the film, approximately 1 or 2 frames per second, allowed to devide the process of the movements into minimal movement units, which consisted of the motions of five fingers of a hand. Each movenent unit was coded as to finger motion, hand movement pattern, function and other related factors. The movement patterns were classified using the data base management system. Finally, 7781 units were analysed.
It was found that 88.5 percent of the movement units were consisted of 1 or 2 types of finger motion. In 24% of all the units, the finger motions differed between the thumb and the index finger, and between the index and the other ulnar fingers. The movement pattern “OXOOO”, in which only the index finger moved, was the most typical one of this type, and constituted 9% of all the movement units. In about 21% of all the units, the finger motion differed between the thumb and the other fingers. The typical patterns of this type were “XOOOO”, in which only the thumb moved, and “XYYYY”, in which the thumb and the other fingers moved differently. Each of these two patterns occupied another 9% of all the units. The pattern “XXXXX”, in which all the finger motions were identical, was seen in 9% of all the units too. The above four patterns as well as the other 12 patterns constituted 68% of all the movement units. The relations of these 16 typical movement patterns with the functions were also examined.
