In this paper we examine two long-standing assumptions of the information processing perspective of perceptual-motor development, namely that: (1) the amount of noise in children's sensori-motor system decreases with increases in age up to adulthood; and (2) this age-related reduction in noise level leads to associated improvements in the accuracy and variability of performance. We show that the age-related differences in the amount and structure of performance variability are influenced by many factors, including task goals, task relevant information, body scale, and practice. White Gaussian noise does not appear to play a role in driving the age-related differences in performance variability. The reduction in children's performance variability with advancing age is primarily due to the evolving constraints of development and experience driven changes in the adaptive structure of their sensori-motor output.