Modulation of perceived motion by illusory contours, and the rigidity assumption

Here we present demonstrations that combine illusory edge motion with Kanizsa figures. The key observation is that even though each local edge of a Kanizsa square signals a vertical or horizontal shift, the global percept is that of rotation. The conflict between the global percept and local motion information is at odds with the observers’ assumption that the perceived figure is rigid and unlikely to deform. The local/global conflict creates a bistable percept that allows an exploration of the relationships between perceptual modes. Variants of the original figure were created to identify and assess critical factors of this phenomenon, including changes in temporal phase and amodal completion of motion.