Egomotion and vection in young and elderly adults

Elderly people tend to rely upon their visual input more than upon that from other sensory systems due to age-related declines. This reliance upon vision places older adults at risk for falls because they are often not aware of the magnitude of their body motion.

The purpose of this prospective study was to determine the influence of stationary anchors and vection upon egomotion in young, young-old and old adult age groups using the moving room paradigm.

Forty-five healthy participants separated into 3 age groups (young, 18-20 years; young-old, 60-69 years; old, 70-79 years) were tested. Participants stood on a force platform in front of an oscillating virtual moving room. Optical flow fields were presented to the central and peripheral areas of the retina, individually and jointly. Postural motion was assessed through center of pressure (COP). There were 5 room conditions used to evaluate the role of central and peripheral vision upon postural motion. Participants rated their vection, perceived amount of motion, and the magnitude of the visual scene motion following each condition.

In all optical flow conditions, old adults produced more postural motion than the young and young-old adults. Participants were quite accurate at rating their postural motion and vection with their COP displacement; however, young adults rated their vection higher, yet produced significantly less COP displacement than the older adults. Postural responses were also decreased in both age groups when portions of the visual scene were occluded in central or peripheral vision. These findings indicate visual sensitivity to visual scene motion as a function of age when information is available to all areas of the retina. Static images in the visual scene provide a reference point which was found to assist in the stabilization of body position, decreasing fall risk.

Older adults exhibited increased egomotion, yet decreased vection in response to visual scene motion. It is likely that the reduction in proprioceptive feedback due to healthy aging induces greater COP motion in the older adults before they perceive visual scene motion, placing them at an increased risk for incurring falls.