“By closing one eye, you removed binocular vision, the slight variance in images, called “binocular disparity,” that occurs when we view an object with both eyes open. Binocular vision – sometimes called “depth perception” – allows us to see the world as three-dimensional. When you close one eye, the single image is two-dimensional – that is, it is flat, like a photograph, and therefore can be “copied” onto flat paper.”
