These images of the Leaning tower of Pisa are identical, but the one on the right seems to lean more. This is because the brain treats them as a single scene. Usually when you look up to two adjacent towers they appear to converge near the top due to perspective. However, in this case the two towers have parallel outlines. As a result, your brain assumes the towers are diverging. This illusion demonstrates how your visual system tends to treat two side-by-side images as if part of the same scene.