Visual transformations underlying apparent movement

Apparent movement of a rigid object is seen when two different views of the same object are separated by relatively long distances and times. In a series of experiments, the minimum stimulus-onset asynchrony (SOA) required for the apparent form-preserving movement of an object was recorded. In Experiment 1, an object was alternately displayed in two positions obtained by displacing and rotating the object about the center of the display screen. In Experiment 2, objects varying in size were presented in alternate positions, again differing by both location and orientation. In Experiment 3, stimulus location and orientation were varied orthogonally. In all three experiments, the minimum SOA was predicted by a linear combination of the distance separating the two locations of the object and the angle separating the two orientations of the object. The results support the hypothesis that the long-range apparent movement of a rigid object may be constructed by internal processes corresponding to rotation and translation of the object.