Learning to bounce: first lessons from a bouncing robot

Abstract

Introduction Ten years ago, Goldfield and colleagues [1] performed a longitudinal study in which eight 6-months old infants were strapped in a harness attached to a spring of known stiffness and damping, and were observed once each week for a period of several weeks, while they learned to bounce. At the onset of each experimental session, it was made sure that the soles of their feet could just touch the floor. Goldfield et al. found that in the course of learning to bounce, the infants' motor activity could be decomposed into an initial assembly phase in which kicking was irregular and variable in period, and a subsequent tuning phase characterized by bursts of more periodic kicking and long bouts of sustained bouncing, during which infants seemed to explore the mechanical properties of the mass-spring system. A third phase was initiated by a sudden doubling of the bout length, and was characterized by oscillations of the mass-spring system at its resonant frequency, a sensible rise