PERCEPTUAL SCALING OF WHOLE-BODY LOW-FREQUENCY LINEAR OSCILLATORY MOTION

Evidence that Z-axis oscillation in the Earth more provocative of moti on sickness than the equivalent imposed oscillation acting in the Eart h-horizontal raises the Possibility that horizontal oscillation is per ceived as less intense than equivalent vertical oscillation. In Experi ment 1, subjects (n = 8) were oscillated through their head Z-axis in both the Earth-vertical and horizontal planes. In Experiment 2, anothe r group (n = 10) were oscillated through their head Y-axis in the Eart h-horizontal. Stimuli were 5 cycles of motion at 0.3 Hz ranging in 3.5 dB intervals from 0.19 to 2.15 m . s-2 (Expt. 1) and from 0.1 to 3.98 m . s-2 (Expt. 2). Perceptual scaling of intensity against accelerati on was similar irrespective of direction of oscillation in the Earth-p lane or head-body axis. Displacement tended to be overestimated, this being most marked for the lower acceleration levels in the horizontal condition. Results supported the notion that Stevens' Power Law expone nts decrease as a function of increasing stimulus range. Differences i n perception of oscillation intensity and displacement do not seem to explain the markedly greater nauseogenic potential of vertical oscilla tion.