Abstract
In this paper, hybrid brain-computer interface (BCI) that merges event related potentials (P300) and steady state visual evoked potentials (SSVEP) simultaneously is proposed to enhance the performance of four-choice command system. Here we integrate human facial structure in external visual stimulus to evoke stronger cortical responses in hybrid SSVEP+P300 BCI and compare it with non-face stimuli. We also addressed question of feasibility of eliciting one potential by face and other by non-face stimuli. To evoke SSVEP and P300 responses, paradigms with non-face stimuli, neutral face stimuli, and facial expression changes stimuli are proposed. We also projected additional paradigm where SSVEP is elicited by non-face and P300 by flashing different facial expressions. Results proved the last paradigm evoke stronger cortical potentials and thereby improve system accuracy and ITR than other paradigms. We discuss external stimulus parameters that might affect simultaneous evocation of multiple brain potentials and their deterioration effect on individual potentials. Ten healthy volunteers (seven male, aged 22-28 years, mean 25.6 years) contribute in our experiment. LCD screen with refresh rate of 60 Hz is used for external stimulus and all trials are performed in darkened room. The ideal BCI system should have maximum ITR and comfortable rating. We have proven among our paradigms, face emotional and flickering paradigm has maximum comfortableness with highest ITR. In this paper, we have proposed four paradigms as non-face paradigm, face neutral paradigm, face emotional paradigm, and face-emotional and flicker paradigm. We have tested all paradigms and compared them with each other about potential response strength, accuracy, ITR and comfortableness. Result show that face-emotional and flicker paradigm performed better in all aspects than all four paradigms.
Published Version
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