In general, these results suggest that the dynamic system responsible for the control of sitting does not change its basic organization between 5 and 13 months of age, but that the system shows improvements in its consistency and coordination during this period of time. Currently, we are investigating additional nonlinear tests of the postural control system to learn more about how the dynamics underlying this process changes with age.
We would like to conclude with three generalizations from this research. First, postural control is a dynamic process involving sensory-motor transformations that are responsive to local conditions. Second, the study of the process of postural control requires quantitative assessments of time- sampled behavior in different stimulus conditions. Third, postural control is a complex dynamic process that most likely cannot be completely modeled by a set of linear equations, but instead demands nonlinear analyses. Recent developments in the field of nonlinear dynamics are making these analyses more accessible to behavioral researchers, and our preliminary findings are encouraging in suggesting that these analyses offer a new level of precision and insight into dynamic processes.