In Depth

Which monster is larger?

To most people, the one in the background seems larger, though in fact they are exactly the same size. But the depth cues in the picture (the receding tunnel) gives the 2D image a 3D feel. Although both monsters create the same size image in our eyes, our brains take the depth cues into account, which results in a perception of the upper monster as further away—making it seem larger.