by Jesse Hoey
Facial expression is an important element in human communication. The dominant school of thought is that the human face expresses the underlying emotion of the human (the Emotion View). That is, a person is in an emotional state, and this state is expressed in their face. They can attempt to hide the emotion, but there is often some detectable leakage. The emotion view has recently been challenged by a number of authors. They propose an alternative view of facial displays are signals of social intent (the {\em Behavioral Ecology View}). Behavioural ecologists believe that facial expressions have arisen through natural selection because they have proven useful for survival. This implies then, not only that humans would use their faces for purposes other than expression of emotion, but also that humans would refrain from displaying their emotions in their face. I will discuss these two views, and the implications of the ecological view for human-computer interaction using facial expression. I will then describe a model for facial expression recognition based on these implications.