As a student of nonverbal communication, I'm always fascinated when a new tidbit comes along. It appears that there is one more universal microexpression to add to the current list of seven, and that is the "not" face, or the face that says "I don't agree". It isn't completely unique, instead it borrows from the expressions of digust, anger and contempt. The other four previously identified microexpressions are fear, sadness, surprise, and happiness. Here's a good explanation of all of this.