Purchase this article with an account.
Brian Rogers, Katherine Young, Shelley Tootell; Optic flow and the maintenance of balance. Journal of Vision 2007;7(9):1023. doi: 10.1167/7.9.1023.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Using their swinging room, Lee and Lishman (1975) reported that vision plays a dominant role in the maintenance of balance: observers swayed in synchrony with the room as if “hooked like puppets”. While the optic flow from nearby surfaces does induce sway, we found that the induced sway was small when the swinging room had more typical room dimensions and observers stood on a firm surface (Rogers and Richards, Perception 2005). The first objective of the present study was to assess the relative effectiveness of the optic flow created by different surrounding surfaces: the floor, the side-walls and the facing-wall. Body sway was monitored using an overhead camera while observers stood in a real (suspended) swinging room (3m by 3m). The frequency content of sway patterns was analysed using discrete Fourier analysis. The gain of flow-induced sway (amplitude of body sway@room frequency ÷ amplitude of room movement) was found to be [[lt]] 0.4 when the floor and walls were visible. When only the floor surface was visible, (i) gains averaged ∼ 0.2, (ii) sway was not always maximal at the room oscillation frequency and (iii) the phase of the sway was not closely coupled to the room movement. Our second objective was to investigate flow-induced sway under open loop conditions. Body sway was monitored while observers stood in a virtual swinging room (floor only) that could either (i) remain stationary or (ii) move in synchrony with the observer's natural sway (open loop condition), or (iii) move in the opposite direction to the observer's sway (enhanced flow condition). In Experiment 2, sway was only slightly greater under open loop conditions and only slightly less with enhanced feedback. Taken together, these results provide further evidence that optic flow is not necessarily the most important factor in the maintenance of balance.
This PDF is available to Subscribers Only