For simulating communicative behavior, realistic appearance and plausible behavior is important. Postures and mimics also reflect emotional behavior. There exist various models of emotion, like the psycho-evolutionary theory developed by Plutchik [1], or Ekman's FACS. But most models are only suited for muscular expressions. A more unattended field however, also in graphics, is the change in color. Also, other physiological symptoms like crying are left unconsidered. Read more