Effects of design features in gaze-based use of speech-generating devices

Objectives: The design and layout of grid displays can substantially impact the usability of augmentative and alternative communication devices. This study examined effects of two design features, display size and background colours, when gaze control is used for operating a speech-generating device. Methods: Participants selected pictorial symbols on a computer screen to construct three-word messages. The symbols were presented in either a small grid (32 icons) or a large grid (50 icons). They were organised by word categories, with either distinct background colours or a uniform white background. Results and Conclusions: Consistent with studies involving manually operated speech-generating devices, our results showed a significant interaction between grid size and background colour, reflected that background colours reduced the impact of grid size. The advantage of faster selection speed in a small grid weakened by the presence of background colours. In addition, the advantage of a small grid did not affect selection speed of the first word in a sentence, but the second and third word.