Silent agents: From observation to tacit communication

Observation is the basis of a very crucial form of Communication without words or special protocols. Efficient coordination - in humans but also in artificial Agents - exploits or should exploit not just 'observation' but more precisely this form of silent communication: when Agent X relies on the fact that Agent Y is observing her in order to let Y understand that p, i.e. for communicating to Y that p. The general theory of behavioral implicit communication (BIC) is presented. Its importance in social interaction is discussed. We will illustrate why this is crucial for mutual understanding and for comitment and norms keeping, imitation and learning, etc. The message-sending paradigm dominating CSCW, MAS, HCI, and H-Robot-I, is criticized. The relationship with the ill-defined but important notion of stigmergy (very used in ALife Agents) is analyzed.