Ephemeral Paths: Gradual Fade-In as a Visual Cue for Subgraph Highlighting

Ephemeral highlighting uses the temporal dimension to draw the user's attention to specific interface elements through a combination of abrupt onset and gradual fade-in. This technique has shown promise in adaptive interfaces, but has not been tested as a dynamic visual encoding to support information visualization. We conducted a study with 32 participants using subgraph highlighting to support path tracing in node-link graphs, a task abstracting a large class of visual queries. The study compared multiple highlighting techniques, including traditional static highlighting (using color and size), ephemeral highlighting (where the subgraph is emphasized by appearing first, and the rest of the graph fades in gradually), and a combination of static and ephemeral. The combination was the most effective visual cue: it always performed at least as well or better than static highlighting. Ephemeral on its own was sometimes faster than the combined technique, but it was also more error prone. Self-reported workload and preference followed these performance results.