The Special Role of Distant Structures in Perceived Object Velocity

How do we judge an object's velocity when we ourselves are moving? Subjects compared the velocity of a moving object before and during simulated ego-motion. The simulation consisted of moving the visible environment relative to the subject's eye in precisely the way that a static environment would move relative to the eye if the subject had moved. The ensuing motion of the background on the screen influenced the perceived target velocity. We found that the motion of the "most distant structure" largely determined the influence of the moving background. Relying on retinal motion relative to that of distant structures is usually a reliable method for accounting for rotations of the eye. It provides an estimate of the object's movement, relative to the observer. This strategy for judging object motion has the advantage that it does not require metric information on depth or detailed knowledge of one's own motion.