Riddles are an excellent way to examine how someone thinks and what their preconceptions are, according to researchers. That’s why you can hear many different answers to the same question based on who is standing in front of you. Mike had a concussion. His wife is about to give birth. Can you help him remember which one is his pregnant wife?

But, at the end of the day, there is only one answer to most riddles and especially those that require the full attention of your eyes. Sometimes we look at an image and something immediately catches our attention because it is not where it should be. Other times we feel that something is wrong, but we don’t understand exactly what it is and so we have to look more closely.

Then we notice details that we haven’t seen before and find more and more inconsistencies. Okay, that doesn’t usually happen in everyday life, but it does happen in our selection of images with strange errors that are difficult to detect.