The theory of distributed cognition is recognised as being relevant to system analysis
and design but it has lacked visibility for practice. In this paper I develop a codified
method of analysis based on distributed cognition which provides both structure and
guidance in the use of the theory. The method developed comprises a systematic
exploration and description of three functional levels of a system, namely, the
information flow model, physical model, and artefact model. These levels are
analytically separate but integrate in modelling the propagation and transformation of
information within a system. The approach to developing this method has been
exploratory and iterative: developing the understanding of distributed cognition and
contextual study literature, with practical application to the London Ambulance Service
Central Ambulance Control room context. The application of the method to this context
reveals a number of design issues and concerns lending support to its use in these
situations. Furthermore, this paper introduces a conception of how distributed cognition
can be used to deliberate about potential design scenarios, which is a use of distributed
cognition that has been alluded to but has not been explained elsewhere. This paper
makes progress in narrowing the gap between distributed cognition theory and practice
by adding guidance through a structured codified methodology. The method provides
an accessible, practical approach to analysing team based systems using distributed
cognition
