The developmental origins of bimanual coordination: a dynamic perspective.

Patterns of interlimb coordination associated with infant reaching fluctuate frequently over developmental time. This study investigated whether these fluctuations are related to coordination tendencies. Interlimb patterns were studied in reaching and nonreaching movements in 4 infants, which were followed through their 1st year. Each week, reaching and nonreaching endpoint kinematics were recorded in both arms during multiple 14-s trials. It was found that patterns of interlimb coordination in reaching matched coordination tendencies in nonreaching. Reaching fluctuated between uni- and bimanual periods. During the bimanual periods, nonreaching interlimb activity tended to be synchronous. During the unimanual periods, nonreaching activity revealed no predominant form of interlimb coordination. It is argued that changing coordination tendencies may influence the organization of specific goal-oriented behaviors from early in life.