Distributed Cognition is probably one of the most important concepts related to network culture and information architecture. I've been doing a good bit of reading & note-taking on the subject for class & research, so I think it's past time for me to type out some musings on DC. Maybe this will even receive some feedback... nah. Nobody reads these things, at least not mine.
1. D. C. is an old concept that has been revamped in recent discussions, especially those concerned with the effects of networked activity and collaborative space upon cognitive achievements. According to Cole and Engestrom, it was Goethe who supposedly first remarked that everything has been thought of before, and nothing is new under the sun. I know that Roland Barthes made a similar assessment in "The Death of the Author," when he labeled all authors scriptors, or cultural scribblers who write down collective ideas into texts.
Barbara Winsor gives an activity-based definition of distributed cognition in her article "Learning to Do Knowledge Work in Systems of Distributed Cognition" (Journal of Business & Technical Communication 15.1, 2001): "Distributed cognition treats thinking not as an action that takes place wholly inside an individual's head but rather as an activity that is distributed among the individual, other people, the physical environment, and the tools the person uses, including language and such language structures as genres" (p. 6). Language and language structures being socially constructed, this makes sense. Simply put, new knowledge depends upon old. Thinking does not occur in a vaccuum (unless you're vacuous, in which case we don't want to know).
2. Applying this to networks is a simple and necessary step in developing our information structures, which are slowly filling all knowledge spaces. People constantly communicate. Teams are broken up over the information network, and collaboration is an increasingly instantaneous mode of development. Human-computer interaction is becoming more and more network mediated human-human-human (ad infinitum) communication. Computer networks allow for instant feedback and cumulative development: the open-source software movement is a glaring example of this. At my university, D.C. and open-source are important facts of life: Red Hat's headquarters is on our campus, and our colleges of engineering and design are among the best in the world.
3. Taking all of this into account, it follows that future information design and evaluation must evaluate the effects of distributed cognition. How are users interacting with the tools presented by technological factors? This is something that designers have not considered as much in the past - engineers are usually poor evaluators of usability and human factors.