www.theguardian.com/childrens-books-site/gallery/2015/sep/25/the-worlds-most-brain-twisting-puzzles-in-pictures

Your brain makes use of remembered data and patterns in memory to find matches or identify when it encounters something new or unfamiliar. Take a good look at the image above. At first glance it just looks like a random collection of black splodges, but look longer and your brain may begin assembling a pattern familiar to it from memory.