Edinburgh Napier University

  Linear diagrams have been shown to be an effective method for representing set-based data. Moreover, design principles have been empirically developed that, when followed, improve the efficacy of linear diagrams. These principles are task-independent. However, linear diagrams may be produced to aid with a variety of tasks, for which different representations may be more effective. In this paper, we introduce simple interactivity into linear diagrams. Namely, we gave users: the ability to move sets; the ability to move overlaps (set-intersections); and the ability to focus the diagram on a particular group of sets. Whether these interactions improved cognition was investigated via two empirical studies. In the first, we observed that interactivity improved participants' accuracy, confidence and speed. In the second, we observed that these improvements were based on the diagrams participants produced in the first study, rather than being an artefact of interactivity itself. We conclude that adding simple interactivity is useful in the case of linear diagrams.