views updated

vection is the sensation of movement of the body in space produced purely by visual stimulation. Everyone is familiar with the impression of self-motion experienced when watching a moving train through the windows of a stationary train. Powerful experiences of this kind occur when viewing surround cinema (IMAX) and virtual reality displays, which fill much of the visual field. Vection can be linear (apparent forward or backward motion) or angular (corresponding to angular body motion). The basis of vection lies in the close association between the processing of visual and vestibular motion in the brain. In part, this perceptual response to sustained visual motion has probably evolved as an adaptation to the fact that signals from the vestibular apparatus in the inner ear decay quite quickly during constant rotation or linear movement of the head. The sensation of vection produced purely by visual stimulation tends to build up fairly slowly, in a way that complements the decay of the vestibular sensation of movement. So, when we rotate with respect to a stationary visual world, the vection reinforces the sense that it is we who are moving, not the visual world itself, which we expect to be stable.

Graham Barnes, and Colin Blakemore

See also vestibular system; vision.