In 2008, Rutger’s professor Thomas V. Papathomas won the Best Illusion of the Year contest for his rolling eyes on a hollow mask illusion. The hollow mask appears to be a regular 3 dimensional face. You can see the eyes rolling around as the mask is rotated. Illusionary motion occurs because of the depth inversion of the mask as it is rotated. When a 3 dimensional item is added, such as the nose ring he uses in the attached video, the item appears to be moving in the direction opposite of the mask. He created the mask illusion to prove his theory regarding the way people perceive their environment and stimuli within their environment as they move throughout it. His theory states that our visual systems operate by creating a 3-D depiction of the environment while using vestibular and proprioceptive inputs to calculate the predicted retinal flow under self-motion. This retinal flow is used to determine the objects motion by using the degree to which the objects actual versus predicted retinal flow differ. The attached article offers a more detailed explanation of his theory and how the illusion supports it.