A Novel Oddball Paradigm for Affective BCIs Using Emotional Faces as Stimuli

The studies of P300-based brain computer interfaces (BCIs) have demonstrated that visual attention to an oddball event can enhance the event-related potential (ERP) time-locked to this event. However, it was unclear that whether the more sophisticated face-evoked potentials can also be modulated by related mental tasks. This study examined ERP responses to objects, faces, and emotional faces when subjects performs visual attention, face recognition and categorization of emotional facial expressions respectively in an oddball paradigm. The results revealed the significant difference between target and non-target ERPs for each paradigm. Furthermore, the significant difference among three mental tasks was observed for vertex-positive potential (VPP) (p < 0.01), late positive potential (LPP) / P3b (p < 0.05) at the centro-parietal regions and N250 (p < 0.003) at the occipito-temporal regions. The high classification performance for single-trial emotional face-related ERP demonstrated facial emotion processing can be used as a novel oddball paradigm for the affective BCIs.