Abstract
Self-motion perception refers to the ability to perceive egocentric speed and direction of movement through space and is typically informed by several different sensory systems. Currently, little is understood about how aging and experience affect self-motion perception when walking under reduced sensory conditions. Therefore, this experiment compared the spatial updating performance of healthy younger adults (ages 20-25), healthy older adults (ages 60-72), and high-level, large-area, team sport athletes, under sighted walking, blind-walking, and imagined walking conditions using a previously described continuous pointing task (Campos et al., PLoSOne, 2009). Participants viewed a target positioned in front and to the right of them. Then, with eyes open or closed, they pointed continuously towards the target as they walked past it, or imagined walking past it along a straight, forward path. Pointing behaviour was tracked using an Optotrak motion capture system (NDI, Waterloo, ON), which provided 3D tracking of the head, trunk and pointing hand at 60Hz. It was expected that, if accurate spatial updating occurred, the maximum arm azimuth velocity should be observed upon target passage when the arm azimuth angle was zero degrees. Results showed that younger and older adults demonstrated this characteristic pattern of pointing during both sighted and blind-walking (95-98% of maximum arm azimuth velocities occurred at zero deg.), but not during imagined movement; particularly in older adults (80% and 62% for younger and older adults respectively). Interestingly, for athletes, pointing during imagined walking resulted in responses that were much more consistent with responses during actual self-motion (88% of maximum arm azimuth velocities occurred at zero deg). Overall, this study suggests that older adults can spatially update using non-visual inputs during walking, but demonstrate clear failures in motor imagery in the absence of relevant sensory inputs. In contrast, athletes demonstrated a superior ability to perform locomotor mental imagery.
Meeting abstract presented at VSS 2012