The Rotating Glass Illusion: Material Appearance Is Bound to Perceived Shape and Motion

We report a novel illusion in which a rotating transparent and refractive triangular prism (glass object) is perceived as being made of a specular reflective material (mirror), and simultaneously, its direction of rotation (clockwise or anticlockwise) is also misperceived. Our findings suggest that physical motion strongly influences viewers' judgements of material in some situations.