Towards gaze-independent c-VEP BCI: A pilot study
S. Narayanan S. Ahmadi P. Desain J. Thielen
A limitation of brain-computer interface (BCI) spellers is that they require
the user to be able to move the eyes to fixate on targets. This poses an issue
for users who cannot voluntarily control their eye movements, for instance,
people living with late-stage amyotrophic lateral sclerosis (ALS). This pilot
study makes the first step towards a gaze-independent speller based on the
code-modulated visual evoked potential (c-VEP). Participants were presented
with two bi-laterally located stimuli, one of which was flashing, and were
tasked to attend to one of these stimuli either by directly looking at the
stimuli (overt condition) or by using spatial attention, eliminating the need
for eye movement (covert condition). The attended stimuli were decoded from
electroencephalography (EEG) and classification accuracies of 88% and 100% were
obtained for the covert and overt conditions, respectively. These fundamental
insights show the promising feasibility of utilizing the c-VEP protocol for
gaze-independent BCIs that use covert spatial attention when both stimuli flash
simultaneously.