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134 Chapter 4 Design for collaboration and communication I

Air traffic controller
(ATC)

control center

alert
aob

Propagation of representational states:
1 ATC gives clearance to pilot to fly to higher altitude (verbal)
2 Pilot changes altitude meter (mental and physical)
3 Captain observes pilot (visual)
4 Captain flies to higher altitude (mental and physical)
Figure 4.1 6 A cognitive system in which information is propagated through different media.

they use, and the environment they are working in. An example of a cognitive sys-
tem is an airline cockpit, where a top-level goal is to fly the plane. This involves:
the pilot, co-pilot and air traffic controller interacting with one another
the pilot and co-pilot interacting with the instruments in the cockpit
the pilot and co-pilot interacting with the environment in which the plane is
flying (e.g., sky, runway).

A primary objective of the distributed cognition approach is to describe these
interactions in terms of how information is propagated through different media. By
this is meant how information is represented and re-represented as it moves across
individuals and through the array of artifacts that are used (e.g., maps, instrument
readings, scribbles, spoken word) during activities. These transformations of infor-
mation are referred to as changes in representational state.
This way of describing and analyzing a cognitive activity contrasts with other
cognitive approaches (e.g., the information processing model) in that it focuses not
on what is happening inside the heads of each individual but on what is happening
across individuals and artifacts. For example, in the cognitive system of the cockpit,
a number of people and artifacts are involved in the activity of "flying to a higher
altitude." The air traffic controller initially tells the co-pilot when it is safe to fly to
a higher altitude. The co-pilot then alerts the pilot, who is flying the plane, by mov-
ing a knob on the instrument panel in front of them, indicating that it is now safe to
fly (see Figure 4.16). Hence, the information concerning this activity is transformed