Parallel Arc Diagrams: Visualizing Temporal Interactions

This paper introduces a new computer-based visualization method, the parallel arc diagram (PAD), which is capable of uniquely representing 2-mode temporal relationships in a manner that assists in highlighting simple features of the network. The PAD approach relies on a computer’s ability to render link lines adjacent to each other with orderly precision, resulting in features that facilitate preattentive processing of simple network characteristics and providing the ability to discern patterns of interactions over time. PADs supplement existing methods such as node-link diagrams by offering a simple alternative visualization without the computational complexity of graph layout algorithms and the additional issues that animation introduces. This paper subjectively evaluates the PAD approach using low level task taxonomies developed for assessing adjacency matrix and node-link visualization effectiveness. We argue based on those taxonomies that the PAD approach is as effective or in some cases more effective than existing approaches except for tasks requiring the identification of structural groups or middle-man nodes. This paper also demonstrates how the PAD approach can be utilized in a software application. The TIPAD (Temporal Interactive Parallel Arc Diagram) uses character participation in movie scenes as a test-bed for exploring social interactions over time and provides the ability to compare a PAD based visualization with traditional visualizations of the same network.