Why are some representations (sometimes) more effective?

Graphical representations are used heavily in systems analysis and design without proper verification of their usability. However, different representations have varying impacts on the effectiveness of systems analysts. The objective of this study was to explore the effects of diagrammatic representations on task behavior and performance. A cognitive model of an analysis and design task using diagrams was proposed, from which hypotheses about the effects of diagrammatic representation on task behavior and performance were derived. A laboratory experiment was conducted to test the hypotheses. Results of the experiment show that the representational features of the diagrams induced subjects to adopt different problem solving strategies, which resulted in different task performances.