Abstract
The objective of this study was to assess the development of visuo-motor integration across life-span by measuring the postural reactivity in response to an immersive moving virtual tunnel. Seventy participants whose ages ranged from 5 to 75 years old were tested. They had a normal or corrected to normal visual acuity and a normal stereoscopic vision. Each participant was placed in a virtual tunnel that oscillated in an anterior-posterior fashion at 0.125 Hz, 0.25 Hz and 0.5 Hz. Participants' Body Sway (BS) and Instability Index (II) were measured with a magnetic motion sensor located at the head level. The same two measures were also taken during the fixation of the static tunnel condition and during the eyes closed condition (no visual cues available). A significant main effect of age was found for both BS and II, where children (5 to 16 year-old) and the elderly (65 year-old onward) were more reactive to the stimulation than were the adults (17 to 60 year-old) for all dynamic conditions. Our results suggest that visuo-motor integration, as defined by postural reactivity is not fully developed until 16 to 19 years old as indicated by younger than 16 year-old children's over-reliance on vision to control their posture. This over-reliance on vision disappears during adulthood but seems to come back at an advanced age (65 years onward). Possible explanations are that children over-rely on vision because the primary elements for postural control are not fully developed; whereas in aging it might be explained by a degradation of these systems forcing observers to “spread the load” across alternate sensory systems.
Supported by: NSERC, NSERC-Essilor Chair, CFI and CIHR.