ABSTRACT
This paper proposes that a novel form of cognitive analysis for diagrammatic representations is in terms of the functional roles that they can play in problem solving. Functional roles are capacities or features that a diagram may possess, which can support particular forms of reasoning or specific problem solving tasks. A person may exploit several functional roles of a single diagram in one problem. A dozen functional roles have been identified, which can be considered as a framework to bridge the gulf between (i) studies of the properties of diagrams in themselves and (ii) investigations of human reasoning and problem solving with diagrammatic representations. The utility of the framework is demonstrated by examining how the functional roles can explain why certain diagrams facilitate problem solving in thermodynamics. The thermodynamics diagrams are interesting, in themselves, as examples of complex cognitive artefacts that support a variety of sophisticated forms of reasoning.
