Quantifying variability in phase portraits: Application to gait ontogeny

We describe new Fourier- and shape-based methods for quantifying variation in phase-portraits, and re-analyze previously-published ontogenetic and adult data [Clark, J. E., & Phillips, S. J. (1993). A longitudinal study of intralimb coordination in the first year of independent walking: A dynamical systems approach. Child Development, 64, 1143–1157]. Results show considerable variation between individuals and through development, but after 6 months of walking some gait patterns stabilize.