Our discussion has to start with this seminal article. The extended mind hypothesis seems to have generated a mini-industry.
*Clark, A., & Chalmers, D. (1998). The extended mind. Analysis, 7-19.
An elaboration of Andy Clark’s ideas on the topic can be found in Chapter 3 of his book Supersizing the Mind. And here is Dave Chalmers’ foreword to that book.
F. Adams and K. Aizawa, (2004?) “Defending the bounds of cognition” In Menary, R., The Extended Mind, Cambridge, MA: MIT Press.
And Andy Clark’s response: Memento’s Revenge, from the same volume. This discussion ain’t over yet.
A blog post by Andy Clark himself, reviewing Adams and Aizawa’s recent book.
Here is a very cogent criticism: The Extended Breath account of respiration, by Paul Thagard, one of the central figures to classical cognitive science. Discuss this.
Finally, my own contribution to this debate is the Brain in the Ass hypothesis.