An Event-Related Potential Study Of Face-specific Mechanism

Face recognition and object recognition are both important function in social life.Some argue that the brain processes faces separately from other objects, within a domain-specific module dedicated to face perception.In this research we use Event Related Potential method to investigate the functional independence of face and object processing.In the first part of this research, participants were instructed to perform a target monitoring task(with cars as targets) and an animacy decision task(to decide which stimuli are living beings and which are non-living objects), with photos of human faces, cars, birds and chairs as stimuli.We explored how stimulus types and task-associated strategies affected the N170 component by comparing the N170 event-related potentials elicited by human faces, cars, birds and chairs in the two tasks.The second part of this research aimed at examining expertise hypothesis of face processing.According the appoint of expertise, the reason why people show different reaction during face processing is because people are expertise at recognizing human face.We use human faces and primate faces as stimuli in this experiment, participants monitored human faces while primate faces were distracters.EEG data is recorded during experiment.In the result we found: (1) human faces elicited an equally conspicuous N170 under the two task of Experiment 1, significantly larger than the negative ERP components elicited by non-face categories during the same time range.The target status of cars in the target monitoring task results in an enhanced N170.Although the N170 components elicited by cars are significantly smaller than the N170 induced by human faces in this condition, they are significantly larger than the N170 components elicited by birds and chairs, whereas cars elicited a smaller N170 ERPs in the animacy decision task.Generously speaking, people are not expertise in observing primate faces.The N170 elicited by primate faces in human participants was as conspicuous as that elicited by human faces in the same participants, albeitpeaking later.The brain topography also shows that both stimuli have similar potential distribution.This pattern indicates that face-specific mechanism is induced by particular face features that convey certain physiognomic information regardless of expertise.In conclusion, these results probably suggest face-specific processing mechanisms in the human brain, a mechanism which is not influenced by either task or expertise.The processing of other objects is probably accomplished by a more general visual processor, which is sensitive to strategic manipulation.