There are basically two kinds of people in this world: People who love to look at optical illusions, and people who don’t. The people that hate them find them endlessly frustrating, while the ones who love them enjoy challenging their brains and training their eyes. Images like this differ from objective reality, and they are effective (not to mention challenging) because our minds automatically try to find the easiest way to look at things.
At first glance, your brain will try to find the least difficult interpretation of what you see before you. After a few seconds, though, things begin to change. Suddenly, the image doesn’t make sense and you’re questioning everything you’ve ever known. And the best part of these particular optical illusions? They’re all totally accidental. #39 is the best mistake ever.