CHANGES IN THE SEQUENCING AND TIMING OF MUSCLE RESPONSE COORDINATION ASSOCIATED WITH DEVELOPMENTAL TRANSITIONS IN BALANCE ABILITIES

It has been hypothesized that animals go through phases in behavioral development where movements initially show excessive degrees of freedo m, then are simplified with skill mastery, and are Te-elaborated with learning to reach the same goal through variable means. To determine i f this is true for stages seen in children's balance development we ex plored changes in balance abilities in infants (7-15 months) during th e transition to independent stance. With the emergence of 'pull to sta nd' behavior infants showed excessive movement at the ankle, knee and hip joint and postural muscle responses were disorganized, with delaye d and variable onset latencies. Response organization improved with ex perience in dependent stance. At the onset of independent stance, resp onse patterns again showed increased variability. However, with increa sed experience and the onset of independent walking the response organ ization became consistent and latencies were shortened to more mature levels. With continued experience children began to experiment with al ternate strategies of balance adjustments.