Sophie is at the stage where she thinks that if she can't see you, obviously you can't see her, either. It is pretty humorous to watch her employ this device in order to be sneaky and do things she shouldn't be doing.
Last week, I was rehearsing for my recital with Jackie, and I noticed Sophie getting into my purse, right in front of my very eyes. Well, she started to pull out my wallet as sloooooooooowly as she possibly could, all the while with her head down and looking at the floor. As soon as she had the contraband securely in her adorable little hands, she closed her eyes and ran to hide under a chair. She totally thought she got away with it, because I would rather let her pull all my money and credit cards out than have to hold her while singing.
Another couple funny instances happened this last couple days while my parents were here visiting (they came to see me sing!). My dad is a pretty tall guy, and while Sophie adores him, I can see how he might be a bit scary if she's doing something a little bit naughty. But then, she becomes invisible if anyone catches her doing something a little bit naughty, no matter how big they are.
Anyway, she got a barstool like she always does and started climbing up to the microwave. My dad saw her and asked her what she was doing. She immediately put her ever present blanket right on her head, effectively disappearing. Not much longer after that, my dad caught her getting into the fridge and foraging for eggs. This time, all he did was say her name, and she looked at him and covered her eyes with her hands.
Man, I sure wish I had her super powers of becoming invisible as soon as someone catches me with my hand in the cookie jar. That would be awesome.