The ERP Studies Of Facial Expressions Recognition Under Attentional And Non-attentional Conditions

Facial expressions play an important role in personal communication, as they canconvey abundant emotional information. The research used event-related potential (ERP)to investigate the mechanism underlying facial expressions recognition under attentionaland non-attentional conditions.Studies of facial expressions recognition based on ERP under attentional condition: acontrol paradigm was used to investigate whether N170 was the facial-specific component;whether N170 was regulated by facial emotion content; whether there were expressionaleffects in later positive component. Three kinds of cartoon facial expressions (neutral、happy、angry) and three kinds of non-facial cartoons were presented randomly, subjectswere instructed to see the cartoons carefully and discriminate the type of the facialexressions as accurately as possible.The results indicated that: there were significantdifferences between N170 evoked by facial cartoons and that evoked by non-facialcartoons; there were not significant differences among N170 evoked by differentemotional faces, N170 was not regulated by facial emotion content; expressional effectsappeared at 300～600 millisecond after stimulus.Studies of facial expressions recognition based on ERP under non-attentionalcondition: a modified“cross-modal delayed response”paradigm was used to investigatewhether the visual mismatch negativity can be elicited by cartoon facial expressions, andto define the mechanism underlying automatic processing of facial expressions. Subjectswere instructed to discriminate the type of the tones (800 Hz and 1000 Hz) they heard asquickly and accurately as possible, and to act merely when they heard the responseimperative signal. Neutral、happy and angry faces were presented during intervalsbetween a tone and a response imperative signal. Visual mismatch negativity (VMMN)was obtained by subtracting the ERP elicited by neutral faces from that elicited by happyfaces or angry faces. The angry-related VMMN was more negative than happy-relatedVMMN, VMMN can be elicited by the cartoon facial expressions, facial expressions can be processed automatically.