The 'Ames'ing Room

Ever since I was a kid, I've been fascinated by the Ames Room. I had a couple of old psychology text books (from the fifties) and they reproduced strange pictures like the one here. The people appear to be very different sizes, and yet, we know that it isn't realistic. So what's going on?

As usual, Wikipedia has much more to say on the matter, but simply put, you have learnt that walls are normally to be trusted (and that people come in a variety of sizes). Your brain looks at the scene and ignores the possibility that the walls are somehow not as they seem, for the cheaper conclusion that we're being presented with a very short and very tall person.

But we've been tricked. The walls are distorted so that the person on the left, is much further away than the person on the right. It is the distance which is different, not their height. You can remove the illusion by familiarising yourself with the layout of the room (after which you see the scene correctly). Funny eh?