Extended Mind

  • paper by Andy Clark and David Chalmers
  • propose idea that objects in the environment are part of the mind
  • thought experiment:
    • Otto and Inga are going to a museum
    • Otto has Alzheimer's disease
    • both have a belief of where the museum is
    • Inga consults her memory to know
    • Otto consults his notebook to know (his mind is extended to include the notebook as memory)
    • the only difference in these two cases is that Inga's memory is being internally processed by the brain, while Otto's memory is being served by the notebook
  • this could be extended to also hold parts of memory/thinking in other agents (people, computers, etc...)
  • important to note that "extended mind" is mainly based on language, so other forms of thinking are harder/impossible? (body-thinking, etc.)
  • related to:

The cockpit, with its pilots and instruments forming a single cognitive system, can only be understood when we understand, as a unity, the contributions of the individual agents in the system and the coordination necessary among the agents to enact the goal, that is, to achieve "the successful completion of a flight."

A Small Matter of Programming - Bonnie Nardi

Embodied cognition is the theory that many features of cognition, whether human or otherwise, are shaped by aspects of the entire body of the organism. The features of cognition include high level mental constructs (such as concepts and categories) and performance on various cognitive tasks (such as reasoning or judgment). The aspects of the body include the motor system, the perceptual system, bodily interactions with the environment (situatedness) and the assumptions about the world that are built into the structure of the organism.


The Extended mind thesis, in contrast with the Embodiment thesis, limits cognitive processing neither to the brain nor even to the body, but extends it outward into the agent's world. Situated cognition emphasizes that this extension is not just a matter of including resources outside the head, but stresses the role of probing and modifying interaction with the agent's world.


Epistemic actions alter the world so as to aid and augment cognitive processes such as recognition and search.

Merely pragmatic actions, by contrast, alter the world because some physical change is desirable for its own sake (e.g., putting cement into a hole in a dam).

In Tetris, falling geometric shapes must be rapidly directed into an appropriate slot in an emerging structure. A rotation button can be used. David Kirsh and Paul Maglio (1994) calculate that the physical rotation of a shape through 90 degrees takes about 100 milliseconds, plus about 200 milliseconds to select the button. To achieve the same result by mental rotation takes about 1000 milliseconds. Kirsh and Maglio go on to present compelling evidence that physical rotation is used not just to position a shape ready to fit a slot, but often to help determine whether the shape and the slot are compatible.

— Andy Clark, David Chalmers - The Extended Mind

  • thinking by writing is an example of Extended Mind notion, where thinking happens partially outside of the brain
Szymon Kaliski © 2021