[Studies of visual mismatch negativity elicited by cartoon facial expressions]

A modified "cross-modal delayed response" paradigm was used to investigate whether the visual mismatch negativity can be elicited by cartoon facial expressions, and to define the mechanism underlying automatic processing of facial expressions. Subjects taking part in the tests were instructed to discriminate the type of the tones they heard as quickly and accurately as possible, and to act merely when they heard the response imperative signal. Neutral, happy and angry faces were presented during intervals between a tone and a response imperative signal. Visual mismatch negativity (VMMN) was obtained by subtracting the event - related potential (ERP) elicited by neutral faces from that elicited by happy faces or angry faces. The angry-related VMMN was more negative than happy-related VMMN, and both were more negative in the left than in the right cerebral hemisphere. The results indicated that VMMN can be elicited by the cartoon facial expressions, and the facial expressions can be processed automatically.