Distributed cognition is not a hypothesis on human-machine interaction. It concerns all mechanisms, whether social or artificial, that have the ability to extend cognitive capacities beyond the limits of a natural organism. It is not limited to a type of technological paradigm; a wide range of contexts are concerned, from network computing to the organization of a fire station, a pedestrian crossing, the use of kitchen utensils or a hiking trail. The aim of the research programme considered here is to understand how human cognition functions, irrespective of the dominant paradigm.