Dynamics of posture in 3- and 5-year-old children as a function of task constraints

The postural dynamics of 3- and 5-year-old children were examined under task constraints of one- and two-leg stance with and without vision. Force platform measures showed that motion of the center of pressure increased as the task constraints changed from bipedal to one-legged stance and vision available to no vision, and that this performance decrement was enhanced in the 3-year-old age group. Videotape analysis of the movement of the torso and limbs during the postural task showed that the children attempted to accommodate the decreased stability of the more difficult task conditions by introducing the control of more biomechanical degrees of freedom into the postural action, but systematic compensatory movement pattern strategies were only evident in the older 5-year-old group. These findings are consistent with the notion that compensatory movement strategies for the recovery of postural stability under more difficult task constraints are reflections of experience in exploiting the dynamics of the perceptual-motor workspace.