A Usability Study of Nomon: a Flexible Interface for Single-Switch Users

Nicholas Bonaker, Emli-Mari Nel, Keith Vertanen, Tamara Broderick

ASSETS '23: Proceedings of the ACM SIGACCESS Conference on Computers and Accessibility, 2023.

Many individuals with severe motor impairments communicate via a single switch - which might be activated by a blink, facial movement, or puff of air. These switches are commonly used as input to scanning systems that allow selection from a 2D grid of options. Nomon is an alternative interface that provides a more flexible layout, not confined to a grid. Previous work suggests that, even when options appear in a grid, Nomon may be faster and easier to use than scanning systems. However, previous work primarily tested Nomon with non-motor-impaired individuals, and evaluation with potential end-users was limited to a single motor-impaired participant. We provide a usability study following seven participants with motor impairments and compare their performance with Nomon against a row-column scanning system. Most participants were faster with Nomon in a picture selection task, while entry rates varied more in a text-entry task. However, we found participants had to click more times per selection using Nomon, motivating future research into mitigating this increased click load. All but one participant preferred using Nomon; most reported it felt faster and had better predictive text.