GUIs scaffold novice performance by surfacing command options. Hotkeys enable expert performance by obviating the need for menu search and finicky mouse selections. Though complementary, they are also independent: learning one teaches little about the other. Here, we introduce ExNovo, a hierarchical ternary-branching tree menu interface that unifies GUI and hotkey ideas such that using the interface as a novice leads directly to expert performance. Command selection is done through a memorizable sequence (e.g., 23211) input with a stationary hand and independent from the visualized command options. Experiments 1 and 2 test ExNovo vs a right-click menu system, demonstrating ExNovo is faster. Experiment 3 scales command quantity to ∼400, with sequences up to length six. We find this impacts performance, but that performance improves with practice, ameliorating the interface complexity. We discuss ExNovo's accessibility benefits, applications to games and mixed reality environments, and questions for future research.
Blair et al. (Mon,) studied this question.