The Effect of Stimulus-Onset Asynchrony on Audiovisual Brain-Computer Interface System

Recent years, researches on ERP-based brain computer interface (BCI) were increasingly popular. Visual and auditory based multimodal stimuli paradigms have attracted more and more attention, while studies on the effect of experimental parameters on system performance of them were rarely reported. This study aims at investigating the effects of stimulus-onset asynchrony (SOA) on audiovisual stimuli based BCI system. Therefore, paradigms with different SOA were conducted with long SOA (1000ms), medium SOA (500ms) and short SOA (200ms) paradigms. Visual stimuli paradigms, auditory stimuli paradigms and audiovisual bimodal stimuli paradigms were also included in the study of SOA effect on BCI system. Fifteen healthy subjects participated in the experiment. We analyzed event-related potential (ERP) of mono-visual paradigm and audiovisual paradigm. Results revealed that SOA has no significant effect discrimination of target and non-target stimuli. We found that there is little difference in the latencies of the early components among distinct paradigms, but the difference is reflected in the amplitude which is mainly related to the type of stimulus. This study could provide theoretical guidance for the design of new paradigms on audiovisual bimodal BCI system.