Abstract

In order to investigate the development of cooperatively responsing ability the subjects were made to carry out synchronous and altenate beating of colateral or contralateral hand and foot 1. The synchronous beating of colateral hand and foot developed earlier than of contralateral hand and foot. In addition, handfoot cooperative response developed to higher degree at the right side than at the left. 2. The hand - foot cooperative movement developed later in altenate beating with hand and foot than synchronous one. Development of altenate movement was earlier in the contralateral hand and foot than in the colateral and foot. Twenty percent of the adult subjects could not carry out altenate beating with colateral hand and Foot. 3. A coefficient of variation in time intervals of beating was decreased with advanced age, but smaller in the synchronous movement than in the alternate one. The coefficient was the largest in the alternate movement of colateral hand and foot in little child. However, it was smaller in both synchronous and altenate movementin the subjects older than 13 years old. The above finding indicates that the beat movement differs in difficulty depending upon different combinations of hand-s and feet. This may be determined by the relationship between spinal reflex of four limbs and inhibition of it by the higher system. A movement which needs stronger inhibition and selection of a greater number of reflexes needs a longer time to be mastered. Children can not perform the most difficult colateral altenate movement untill the age of14 or 15 years. Verf.-Referat