Cognition in the head and in the world is the title of the paper Norman wrote to introduce the special issue on situated action (Norman 1993).
a cognitive process can be distributed
among an actor and the environment
external representation
artifacts as cultural embodiment
among many actors
actors co-located in a shared physical space;
situatedness without co-location;
1a and 1b are not mutually exclusive, but 1a is mainly focused on the cognitive, computational aspect of the representation, whereas 1b emphasize that cultural and cognitive artifacts have a particular status: not only physical but also social.
External representation (1a)
In terms of (Zhang, Norman, 1994) distributed cognition is focused mainly on the relationship among internal and external representation:
"The basic principle of distributed representations is that the representational system of a distributed cognitive task can be considered as a set, with some members internal and some external. Internal representations are in the mind, as propositions, productions, schemas, mental images, connectionist networks, or other forms. External representations are in the world, as physical symbols or as external rules, constraints, or relations embedded in physical configurations. Generally, there are one or more internal and external representations involved in any distributed cognitive task."
The material world provides opportunities to reorganize the distributed cognitive system to make use of a different set of internal and external processes. (Hollan et al., 2000).
Artifacts as embodied culture (1b)
All artifacts, the Internet included, are embodied social projects. ... Cultural artifacts are simultaneously ideal (conceptual) and material. They are ideal in that they contain in coded form the interactions of which they were previously a part and which they mediate in the present. They are material in that they exist only insofar as they are embodied in material artifacts. (Mantovani, 2001)
According to this view, an artifact is an aspect of the material world that has been modified over the history of its incorporation in goal directed human action. By virtue of the changes wrought in the process of their creation and use, artifacts are simultaneously ideal (conceptual) and material. Artifacts are material objects, created in the process of goal directed human actions. They are ideal in that their material form has been shaped by their participation in the interactions of which they were previously a part and which they mediate in the present. (Cole, 1997)
Every feature of a book, from the table of contents to the index and footnotes has evolved over the centuries, and readers of early books faced some of the same organizational problems facing the users of hypermedia documents today. Gutenberg's bible of 1456 is often cited as the first modern book, yet even after the explosive growth of publishing that followed Gutenberg it took more than 100 years for page numbering, indexes, tables of contents, and even title pages to become routine features of books. (Lynch et al., 1999).
Social shared knowledge (2a)
Cognition can be distributed among many actors for many reasons:
a single actor can't perform a complex task alone;
a single actor don't know the entire knowledge to accomplish the task;
distributed, overlapping knowledge is less vulnerable, as the organization can survive when one or some actors become absent;
within a cooperative work there are more opportunity to discover and correct errors.
Actors have usually a considerable amount of shared prior knowledge, as members of a community of practice, about how things are supposed to go and how they typically go. In the course of their interactions, they use that shared knowledge as a resource to negotiate or construct a shared understanding of a particular situation.
(Decortis et al., 2000)
Situatedness without co-location
In the traditional working environments communities of practice shares a common physical space, where formal and informal communication take place. Communities of practice not co-located exist far before the advent of internet: big companies and organizations used more traditional technologies, like the mail and the phone, to organize a geographically distributed working community. The internet dramatically accelerated such a process, and nowadays geographically distributed communities are becoming common.
In communities of practice without co-location, the mediation of cultural artifacts becomes explicit.