Visual brain teasers are not only a fun way to pass the time, but they also stimulate your brain and can be beneficial to your intelligence. These “optical illusions” demonstrate that not everything you see is true! According to Susana Martinez-Conde, director of the visual neuroscience laboratory at Barrow Neurological Institute in Phoenix, Arizona, they are important tools in visual research as they help us understand how visual processing works in both normal and diseased brains.