Focus-sensitive dwell time in EyeBCI: Pilot study

In past decades, eye-tracking (ET) became one of the most widespread communication strategies for people with severe motor impairments (as in locked-in syndromes, LIS). ET cameras enable paralyzed patients to move a cursor across a user interface (UI) by means of their gaze, and to activate a selectable UI object after looking at it for a certain dwell time. This procedure is definitely intuitive and acceptable for many users. Nevertheless, such control function of gaze can become prone to errors if the dwell time duration is too short, not customized for each specific user. Considering such issue and the potential of brain-computer interface (BCI) systems in monitoring user's parameters like attention, it is possible to design hybrid ET-BCI solutions - labeled as EyeBCI in this paper - in order to improve the performance and the usability of ET. In this paper, a novel interaction concept is introduced to adapt the duration of the dwell time to the level of mental focus of the user of EyeBCI when he/she wants to select and activate a UI item: the dwell time shortens according to the raise of the observer's concentration, improving the system precision and responsiveness. In order to evaluate this solution, a pilot study was performed to compare different control conditions in terms of task performance and user experience: 3 ET conditions (different by duration of dwell time) and 2 EyeBCI conditions (BCI-triggered activation of UI items and BCI-modulated dwell time). The results demonstrated promising levels of performance and user experience when using the tested implementation of the novel EyeBCI. In addition, the capability of this new interaction paradigm to be self-adaptable to the user's goals has the potential to greatly enhance the usability of ET solutions for patients with LIS.