It's easy to not think about how hard your eyes and brain work around the clock. The brain is processing an incredible amount of sensory information all the time and, for the most part, everything ends up looking "normal." But what if you could mess with that a bit and maybe "confuse" the brain? In this video from Braincraft, you can learn a simple visual illusion that helps you better understand how our eyes and brain take in the world around us -- even when it can be confusing. All you need is a sheet of paper.