Sublime: a hands-free virtual reality menu navigation system using a high-frequency SSVEP-based brain-computer interface

In this work we present Sublime, a new concept of Steady-State Visually Evoked Potential (SSVEP) based Brain-Computer Interface (BCI) where brain-computer communication occurs by capturing imperceptible visual stimuli integrated in the virtual scene and effortlessly conveying subliminal information to a computer. The technology was tested in a Virtual Reality (VR) environment, where the subject could navigate between the different menus by just gazing at them. The ratio between the stimuli frequencies and the refresh rate of the VR display creates an undesired perception of beats for which different solutions are proposed. To inform the user of target activation, real-time feedback in the form of loading bars is incorporated under each selectable object. We conducted experiments with several subjects and though the system is slower than a conventional joystick, users reported a satisfactory overall experience, in part due to the unexpected responsiveness of the system, as well as due to the fact that virtual objects flickered at a rate that did not cause annoyance. Since the imperceptible visual stimuli can be integrated unobtrusively to any element of the virtual world, we conclude that the potential applications of Sublime are extensive, especially in situations where knowing user's visual focus can be relevant.