Developmental research has focused on the visual control of posture by studying infants and children in a ``moving room.'' [FIGURE 1] In this paradigm, the child sits or stands on a stationary floor while the surrounding walls and ceiling move forward or backward. This movement produces visual information congruent with the head moving in the opposite direction. If the optical flow is perceived as specifying self-motion (and not object motion), then the infant will show a postural compensation.
Figure 1: Schematic representation of the moving room.
In the first study with this paradigm, Lee & Aronson (1974)  reported that infants who were just beginning to stand would sway or stagger when the walls moved. Additional evidence for the coupling between vision and posture was reported by Butterworth & Hicks (1977)  and Bertenthal & Bai (1989)  who showed that infants who could sit independently would produce postural compensations of their head and trunk when tested in the moving room. More recently, Jouen (1990)  reported that even newborn infants show postural compensations of their head when stimulated by an optical flow pattern.
In general, this research has been fairly successful in showing that postural control develops gradually in a head to toe direction. However, the approach has been restricted to measuring global responses with summary statistics. More specific questions concerning how infants use visual information to modulate the timing and force of their postural responses, or how the stability of the system changes over time, are left unanswered. In order to address these questions, it is necessary to modify the previous paradigm to allow for the collection of more detailed data over a longer period of time.