Figure 2.

(A) Motor reactions of the mean body excursions of young and elderly subjects in relation to platform tilts. Shown are motor reactions in degrees of the upper body (angle UB), lower body (angle LB), and platform movements (sample stimulus, black bottom line). The traces of the young and elderly groups represent means across all subjects at 1° stimulus amplitude with eyes closed (s, seconds). (B) Experimental setup. Picture of a subject standing on the platform. For safety reasons subjects held ropes in their hands which hung loosely from the ceiling. The six linear motors created platform tilts with the axis running through the ankle joints. Angular excursions of the platform, the upper body (UB) and the lower body (LB) in space were quantified with an optoelectronic device using markers attached to shoulder, hip, and a rigid bar on the platform.