[dstorrs]

>"Smile" is not an atomic face state, there are many > gradations within it.

You're not kidding! http://face.paulekman.com/default.aspx

Personally, I've never seen the Mona Lisa's smile as that complicated. Her mouth is smiling, her eyes are not. When you look at the bottom half of her face, you see a smile. When you look at the top half, you don't.