The head movement keyboard that saved the most effort was not the one users preferred.
It is easy to optimise for the thing you can count. In an interface driven by head movement, the countable thing is movement itself, so a layout that shaves gestures off a sentence looks like the better layout. A study of head controlled typing shows why that number is not the whole decision.
Measured purely in motion, the frequency arrangement came first. It took 99 head movements on average, against 106 for alphabetical order and 119 for QWERTY. The gap between the best and the worst is twenty movements, which is a real cost for someone typing with their neck.
Respondents still preferred QWERTY, and the reason they gave was familiarity rather than comfort. The frequency layout was judged easier to use, so users could feel the difference, but habit weighed more. The same split appeared in the control styles. Linear movement, where gestures step the pointer around, was preferred to free movement, where the head acts as a mouse and a key is chosen by holding still for three seconds.
That strain note matters for the accessibility case behind this work. Hands free input is often proposed for drivers, for industrial workers, and for people who cannot use a keyboard at all, and for the last group physical effort is not a footnote but a central design constraint. A layout that saves movements while demanding more concentration may be the wrong trade.
The prototype ran on iPhone sensors through CoreMotion, with iOS 7.1 as the floor, and the authors point to a full application as the next step. The lesson to carry forward is that the fastest layout and the preferred layout are two different questions, and a design has to answer both.
Herman Tolle et al. (2016). Design of keyboard input control for mobile application using Head Movement Control (HEMOCS). 2016 International Conference on Advanced Computer Science and Information Systems (ICACSIS).
