Dr. Paul Eckman has classified six basic emotions happiness,surprise,anger,disgust ,fear and sadness. they are controlled by facial muscles above your eyes. People can tell when u are fake smiling or making a fake facial exspression. There is a new technology called the facial Action coding system enables computers to identify humans emotions. They also exsplain how people can tell what your emotion is by your facial exspressions. They can tell if you are happy or sad just by looking at you also when u fake smile specialist can tell because it streches your mouth sideways using the zygomatic major and a different muscle. A muscle called orbicularis oculi pars palpabraesus makes crow's feet around your eyes which is also a sign that u have a fake smile. They also explain the steps you can do to show what they are talking about with having "crows feet" when you are fake smiling. moving your facial muscles not only exspressses emotion, but also helps produce them and putting on a happy face eventaully works. some actors have to use these emotions and facial expressions when they are on stage. its crazy how making faces could show so much about emotions.