In this photo, actress Anna Paquin is displaying the classic (although in a mild to moderate amount in this example) expression of contempt. This is an extremely important expression - always accurate and always with consequences. If you see it - there's a problem, either in your marriage or perhaps in your employment.
The fact is most people don't notice this emotion - even in retrospect. It often appears on the face for just an instant - as little as 1/40th of a second. This display is known as a microexpression. It is entirely subconscious. Of course, there are many other emotions which are displayed as briefly. Only about one in 300 people can see microexpressions naturally, but virtually everyone can be taught to see them.