TRANSITIONS IN VISUAL PROPRIOCEPTION - A CROSS-SECTIONAL DEVELOPMENTAL-STUDY OF THE EFFECT OF VISUAL FLOW ON POSTURAL CONTROL

In the present study, a moving room paradigm was used that characteriz ed the developmental progression of the effects of visual perturbation s on stance control in subjects (N = 39) from 5 months to 10 years of age, Kinematic (probability of recording sway, magnitude of sway respo nse) and electromyographic (probability and patterns of muscle activat ion, muscle onset latencies) data were found that suggested that visua l flow simulating sway activates organized postural muscle responses a nd results in subsequent sway in standing infants as young as 5 months of age, well before they are able to stand independently. In new walk ers, there was an increase in the magnitude of the effect of the visua l perturbation, suggesting a possible increase in reliance on visual i nformation. The magnitude of sway decreased to very low levels in olde r children and adults. The large-amplitude responses observed in the y oungest age groups may indicate an inability to switch from an unrelia ble to a reliable source of perceptual information or an inability to modulate the responses produced following the perturbations. With incr easing age and experience, the ability to resolve the conflict increas ed, with adult subjects demonstrating little sway response.