Examination of multi-optioning for cVEP-based BCI by fluctuation of indicator lighting intervals and luminance

In this study, brain-computer interfaces (BCIs) using visual evoked potentials (VEPs) induced by blinking light have been studied. We examined them to change the phase and frequency of the blinking light with variable onset intervals and changing luminance to realize multiple choices in the BCI based on code modulated visual evoked potentials (cVEP) using transient VEP. We used three types of blinking lights with fluctuation interval in addition to one blinking light with fixed interval and attempted to discriminate between the four blinking lights that a subject observed. The amplitude of averaged VEPs with fluctuation interval decreased when a subject did not observe the blinking light. The discrimination rate for the blinking lights was approximately 84%. In addition, we examined the changing luminance of the blinking stimulus to increase the number of multiple choices. In this study, we obtained VEPs based on synchronous addition method and verified the effects of changing luminance and lighting interval in indicators. In addition, our study aims to increase the number of simultaneous choices of cVEP-based BCI using blinking light with variable onset interval and changing luminance. In this paper, we report the possibility of multiple choices by conducting experiments for the estimation of proposed methods.