Conceptual Diagrams: Representing Ideas in Design

Studies in cognition [1, 2] have investigated the role of external visual representations in different domains in supporting reasoning, problem solving, and communication. These studies often are confined to domains that pose relatively well-defined problems [3], such as geometry [4] and physics [2], with fewer studies in domains where the problems are ill-defined [3], such as meteorology [5] and architecture [6]. In many studies of well-defined problems, diagrammatic representations illustrate either causal or temporal relationships between parts of entities and phenomena that the diagram represents. In architecture, diagrams are used to represent causal relationships , such as with orientation diagrams, or temporal relationships, such as with circulation diagrams. There is, however, another kind of diagram that is used to represent the main idea or the core of a design. We call these diagrams conceptual diagrams. They differ, potentially, from other diagrammatic representations studied thus far in that they represent an abstract conceptualization of a potential problem solution. Diagrams in other fields can be interpreted as conceptual diagrams as well, such as a diagram that shows the electron orbiting around a nucleus in atomic physics, or the supply-demand diagram in economics. In the domain of scientific discovery, Nerses-sian [7] has shown how the use of conceptual diagrams helped Maxwell to construct and communicate his representation of the electromagnetic field concept. Conceptual diagrams are abstract representations that embed the core of a concep-tualization of a problem solution. They are concise, yet powerful aids in problem solving in that they provide high-level commitments constraining solutions. In architecture , they embed the core of a design solution encapsulating its generic characteristics and constraints and conveying the form of possible specific solutions. That they are not detailed prevents early commitment to a specific design solution and, thus, they facilitate exploratory reasoning. At the same time they are not ambiguous in the way sketches are in that they fix meaning and define a set of related solutions. This latter is important because design problems are ill-defined in that either the initial state, the goal state, or the operators-or all of them-require further specification. With ill-defined problems there exists a set of potential goal states instead of one goal state. One way that architects delimit the range of alternatives is by analogy. Conceptual diagrams function in a way similar to analogies in that they provide constraints that restrict the set of specified goal states. We propose salient …