text: Then, this software technology has a constructs a 3-D computer model of the face. All 44 majors muscles in the model must move like human muscles. Movement of one or more muscles is called an "action unit". Then Dr. Hunag relies on the work of psychologists, such as Dr. Paul Eckman, creator of FACS ( Facial Action Coding System. Using video imagery, the new emotion-recognition software tracks these facial movements in a real face or in the painted face of Mona Lisa. By weighting the different units, the software can even identify mixed emotions ( as in da Vinci's masterpiece). Each expression is compared against a neutral face (showing no emotion). The new computer software stores similar anatomical information as electric code. This technology can read people's emotions by raising your lips at the corners of your mouth. Then squirt your eyes slightly, to produce wrinkiling. Holding that, raise the outer parts of your cheeks up, toward your eyes.