Neural Mechanism Of Face Specific Recognition

There is a general consensus that mechanisms involved in face processing are "special". It is unclear, however, that what exactly they are specialized for. These mechanisms are selectively involved in processing faces per se, or are selectively involved in structural processing methods, or are caused by the visual expertise processing. There are three different theoretical hypotheses:the face-specificity hypothesis> the visual expertise hypothesis and the structural process specificity hypothesis. Therefore, this study aims to further reveal the nature of specificity of face recognition.The experiment1, which employed the event-related brain potentials to record time courses when16normal young participants made consistency judgment to face/house stimuli with structural/partial changes. The aim is to reveal the nature of specificity of face recognition. The results showed:(1) N170amplitude and latency had a significant main effect at stimulus type. Compared with the non-face stimuli, faces evoked a higher amplitude and shorter latency of N170;(2) there wasn’t a significant difference in processing at amplitude and latency of N170component between face/non-face stimuli.(3) Late components in the time window from300-700msec also had similar results. These results indicated that:(1) the processing of faces and houses (non-face) were different in early and late components, reflecting the specificity of face recognition in early and late time windows.(2) The late ERP components didn’t support that the face processing was whole and structural and non-face object processing was local, part-based.To give a further inspection to the essence of face recognizing specificity, experiment2, which used Chinese characters as a control stimulus, which has similarity with face in some aspects? Stimuli are Chinese characters, adult’s neutral faces, and a class of familiar object Stimuli (houses). Event-related brain potentials were measured to determine time courses of the brain when16normal young participants (19-24years old, with at least15-year Chinese-speaking experiences) finished orientation judgment task for different visual stimuli. To explore whether N170reflects the specificity in face processing or reflects the universality in expertise processing. The main results of this study were as follows:(1) N170was obtained for all the visual stimuli, which amplitudes for different categories have significant differences. The amplitude evoked by faces was the largest and house is the smallest of all;(2) only inverted faces delayed and enhanced N170at right electrodes, the other inverted stimuli (including Chinese characters which have reached experts processing level) did not evoke significant N170changes in amplitude and latency. These observations indicate that:(1) the N170differences between face and Chinese characters should not attribute to visual expertise, but caused by face specific stimulus itself;(2) the N170reflects the specificity in face processing.These results, together with other evidences, demonstrated that the essence of face recognizing specificity is should be attributed to whether face itself. Our results were consistent with the face-specificity hypothesis. The early component of N170might be reflects the specificity in face processing.