Models of human gait are based on adult locomotion. C. E. Bauby and A. D. Kuo (2000) proposed that adults rely on passive mechanisms at the spinal level to control motion in the anteroposterior direction and rely on direct monitoring of postural control in the lateral direction. The authors' purpose in this study was to determine if that model applies to control at the onset of walking in typically developing toddlers (n = 9) and in toddlers with Down syndrome (n = 6). Their longitudinal data suggested that toddlers control gait in a distinctly different manner than adults do. An adult pattern of control emerges with experience. In addition, the effect of experience on the emergence of that pattern is magnified by task-specific early intervention. The present data support the emergence and discovery of efficient patterns of control in this fundamental human behavior. KeywordsDown syndrome; early intervention; gait; variability Control mechanisms of steady-state, stable gait are complex. The goal of understanding those control mechanisms is to recognize how to change or improve performance. To gain an appreciation of the complexity of stable, mature control, one must understand how gait progresses or develops from the earliest, unstable performance toward steady, efficient behavior.

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