Perceived orientation, motion, and configuration of the body during viewing of an off-vertical, rotating surface.

Abstract

Dynamic patterns of activity from multiple receptor systems, as well as efferent signals associated with voluntary movements, influence perceived body motion. The experiment to be described explored how these factors interrelate in influencing apparent body motion. It involved exposing stationary, reclining subjects to a patterned surface which rotated around a vertical or an off-vertical axis. We were able to create situations in which the combined patterns of visual, otolithic, somatosensory, and semicircular canal stimulation actually present were not consistent with body motion in a terrestrial environment. Nevertheless, all of our subjects experienced self-rotation and displacement around a vertical axis. A variety of changes in apparent body orientation, body configuration, and slant of the visual surface occurred concurrently with the elicitation of apparent body rotation. These perceptual remappings were such as to be consistent both with the rotary visual stimulation present and with the absence of changes in otolithic and somatosensory inputs. They were achieved through a reinterpretation of the static otolithic, somatosensory, and proprioceptive signals present. Our findings demonstrate that perceived body motion also depends on representations of what combinations of sensory input are possible in a terrestrial environment.