Visual-Vestibular Interaction: Effects on Self-Motion Perception and Postural Control

The sensation of self-motion is a common visual illusion which allows inferences concerning visual-vestibular interaction. It may be perceived while gazing at moving clouds, streaming water, or when a train moves on the adjacent track in a railway station. This compelling sensation of body movement can even affect postural balance. On first approaching the problem, a psychologic explanation could be suggested in the sense of Helmholtz’s (1896) Urteilstauschung. One might assume that these illusions are inferences based upon the conscious or unconscious assumption of a stable environment, so that when the environment does in fact move, the observer infers that he himself is moving. This interpretation would be consistent with the individual’s past experience as the entire visual surround seldom moves uniformly under natural conditions unless the body moves relative to the earth.