Perceiving Structure From Motion: Failure Of Shape Constancy

Four experiments are reported on human perception of structure from motion that show systematic failures of shape consi:ancy as a function of object motion. Two of these experiments show that the perceived depth of an object undergoing sinusoidal oscillation about a vertical axis increases monotonically with the amplitude of oscillation. The other two experiments show how the shape of an object varies in the neighborhood of a degeneracy within the stimulus domain, at which shape information is absent. These systematic failures of shaps constancy are considered for their implications about the process underlying human perception of structure from motion.