Kirsh, D. & Maglio, P. (1994). On distinguish between epistemic from pragmatic action. Cognitive Science, 18, 513-549. Epistemic actions: physical actions that make mental computations easier, faster ore more accurate. They are external actions that an agent performs to change his/her own computational state.

Pragmatic actions: actions which create physical states which physically advance one towards goal.

So epistemic actions designate a physical action whose primary function is to improve cognition during computation by : -1) reducing cognitive load (space complexity) ; -2) reducing the number of steps required (time complexity) ; -3) reducing the probability of errors (unreliability).

David Kirsh seems to be the guy who is the closest to my research interest in the sense that he studied how distributed cognition rely on external things like use of space, movements and so forth. In another paper (Complenebtary strategies:why we use our hands when we think), he exemplified in which way people encode the state of a process or simplify perception: - pointing - arranging the position and orientation of nearby objects - writing things down - manipualting counters or rulers or other artifacts. - ...