The recent increase of interest in ‘affective computing’is probably due to two—apparently opposite—trends in HCI, On the one hand, the shift of hardware towards computers that are, in a way,‘closer’to the Users body, by being either wearable or ubiquitous, opens the opportunity to monitor new parameters about the Users state and to send them signals that they may seize with all their senses. On the other hand, the shifting of HCI metaphor from ‘using a tool’to ‘interacting with a friend” that takes the appearance of an Embodied Animated Agent that ‘gives the illusion of life” requires recognising the User’s affective state and reacting appropriately to this state, by showing an affectively compatible behavior (Bates, 1994).