How do children control rate, amplitude, and coordination stability during bimanual circle drawing?

Coordination instability (e.g., weak coupling strength) in young children may cause them to control some aspects of coordination in a different manner than adults. This experiment investigated the influence of rate and amplitude on bimanual coordination stability across development (4-, 6-, and 8-year-olds, and adults). Participants traced circles of different amplitudes (5, 10, 15, and 20 cm) while increasing movement rate twice during the trial. The results revealed that 4- and 6-year-olds produced much larger amplitudes than required and increased the amplitude of their movements with increases in rate. Four- and 6-year-olds also produced higher standard deviation of relative phase at all rates than did adults. Discussion examines differences in movement control and the rate-amplitude relation as a consequence of weaker coupling strength in young children than in older children and adults.