Distributed cognition is an emerging perspective in cognitive sciences, where the importance of the environment, the social context and the culture is emphasized. The approach of distributed cognition extends the reach of what is considered cognitive beyond the individual to encompass interactions between people and with resources and materials in the environment. In a distributed perspective a cognitive process is delimited by the functional relationships among the elements that participate in it, rather than by their physical boundaries.
As distributed cognition considers artifacts as elements of cognitive processes, it is gaining an increasing interest in human computer interaction studies.
There are three ways cognition and knowledge can be distributed:
artifacts embody a part of the intellectual story of a culture and are the expression of a implicit theory on the human activity: culture is distributed among artifacts;
cognitive and computational work can be delegated to artifacts;
knowledge can be distributed across the members of a social group.
All these kinds of distributedness could play an important role in increasing the usefulness and usability of web sites and web based appliances, because all are present in the web environment:
web is, nowadays, a cultural artifact with its own semiotic and some wide accepted design conventions; such conventions are the result of a form of "natural selection" and can accomplish the "zero learning time" for new users interacting with the site;
the web is an external artifact that can change the nature of a task being done: well designed web sites could reduce the cognitive load of user, whereas badly designed sites increases the knowledge demands made on the user;
net technologies can often be used to create a space for "communities of practice", using discussion groups, e-mail, chat.
Viewing the interaction between people and the web in a distributed cognition perspective could provide useful insights about usability of web sites and internet based services.