Abstract
The present study aims at clarifying developmental changes in motor function of the arm during early childhood when manipulating a drawing device. 214 children (105 boys and 109 girls), ranging from 30 to 69 months of age, were asked to fill a circle with a pen, and their behavior was monitored through 4 video cameras simultaneously. The following motor aspects of drawing behavior were evaluated: prehension of the drawing device, joint motion in the arm, and the portion of the body contacting the desk. In the younger children, drawing behavior was governed by motions of the proximal joint. As age increased, the moving joint was switched to more distal joints. A dynamic tripod grip was observed in older children who moved their finger joints. The change in which joint moves might be achieved by reducing the degree of freedom of the hand -arm system. These results suggest that acquisition of the dynamic tripod grip and stable suspension of the arm might make it possible to manipulate a drawing device effectively during early childhood.
