There's a famous optical illusion you've probably seen at some point. It's called "My Wife and My Mother-in-Law," and it either shows a young woman looking away . . . or an old woman looking straight ahead. A new study looked into WHY you see the young woman or the old woman. And the researchers found it has to do with your subconscious bias toward your own age. They found that people under 30 saw the young woman the first time they looked at the picture . . . while people over 30 were more likely to see the old woman.