Usability of the super-vowel for gaze-based text entry

We tested experimentally the idea of reducing the number of buttons in the gaze-based text entry system by replacing all vowels with a single diamond character, which we call super-vowel. It is inspired by historical optimizations of the written language, like Abjar. This way, the number of items on the screen was reduced, simplifying text input and allowing to make the buttons larger. However, the modification can also be a distractor that increases the number of errors. As a result of an experiment on 29 people, it turned out that in the case of non-standard methods of entering text, the modification slightly increases the speed of entering the text and reduces the number of errors. However, this does not apply to the standard keyboard, a direct transformation of physical computer keyboards with a Qwerty button layout.