Developmental changes in motor control: insights from bimanual coordination.

Manual dexterity is known to gradually progress with developmental age. In this study, we evaluate the performance of unimanual and bimanual actions under perturbed and unperturbed conditions in children between 4 and 10 years of age. Behavior was assessed by means of trajectory measurements and degree of bimanual coupling. The results showed that the younger children performed less successfully than the older children in the unimanual and bimanual tasks, with a plateau occurring around the age of 8 years. The SWAN rating scale of inattention and hyperactivity/impulsivity correlated with bimanual behavior at this particular age, suggesting that these traits are predictors of intricate skill performance during a critical developmental phase when significant refinement of control mechanisms occurs. The data furthermore revealed that a rebalancing of the between-hand performance asymmetries enabled superior bimanual coordination patterns in the older children. This suggests that progress in bimanual behavior relies on essential changes in unimanual processing and points to a dynamic interplay of circuitry. Overall, the data highlight a progressive change and integration of control systems due to developmental age with behavioral performance being guided by the existing constraints.