Although the argument was not made in these terms at the time, the concept of interactional expertise is important here. In the original critique of AI research, Collins distinguished between behaviour-specific action (capable of being encoded and reproduced by machines) and natural action (what humans do the rest of the time and which machines cannot reproduce). In a later work with Martin Kusch, this same distinction was re-cast as the distinction as mimeomorphic action (action performed in the same way each time and thus amenable to mechanical reproduction) and polimorphic action (actions that depend on context and local convention for their correct interpretation and continuation and thus not reproducible by machines, however sophisticated).