ABSTRACT
We need to locate objects not only in space but also in time. Without the temporal dimension spatial location alone would be of little use to us. Of course, change in spatial location over time is motion. Retinal image motion can be a consequence of displacement either of an object relative to a stationary environment or of an observer relative to a stationary object. In addition both object and observer could move together. All these conditions result in changes in the pattern of stimulation at the eyes, but despite these we retain an appropriate representation both of our position in space and that of the object. Occasionally, errors do occur in our perception of motion, and these can be very instructive in understanding the nature of motion perception.
