ERP Study On Spatio-Temporal Characteristics Of Face Recognition

In this thesis, behavioral performance, event-related potential (ERP) and Brain Electrical Activity Mapping(BEAM)were combined to explore the relationship of face implicit and explicit memory, the differences of implicit positive and negative expression in face domain and investigate the spatial-temporal characteristics of face orientations. The main research work is as follows:1. Researches on process mechanism of face implicit and the relationship of face implicit and explicit memory. Quick showing and shift attention task were to processing distracted things, so as to controlling the processing level of faces. Task was old/new discrimination. ERPs produced by new faces with old faces that were correct classified , which represents a neural correlate of explicit memory(Explicit Memory), and the ERPs produced by new faces with those produced by old faces that were misclassified by the subjects (Implicit Memory) were analyzed. Experiments included two levels which was high attention test and low attention test to explore the effect of implicit process in different loads. Individual difference phenomena, N400, P600 and cross reversal phenomena had been deeply researched. BEAM was combined to study separate character of face implicit system and explicit system in structure. Results indicate that, effect of explicit memory is observed in ERPs from 400ms after stimulus onset at prefrontal and frontal electrodes while effect of implicit memory is seen in ERPs at 300-500ms from central and parietal electrodes. N400 and LPC represent different process course. The conclusion can be gotten that the neural correlates of implicit and explicit memory are dissociated with in a singe task. They show different spatial-temporal characteristics.2. Researches on differences and relationships of neutral face and expression face, positive expression and negative expression.ERP Study of Face Expression adopted"study-test"classical face pattern. In study phase,"face and Chinese characters picture"was showed to let the subjects remember the faces, the Chinese characters and the march about faces and characters. In recognition phase, task was old/new discrimination. ERPs produced by"Chinese characters picture", and the ERPs produced by"face expression picture", and the ERPs produced by"face and Chinese characters picture"were compared. The questions about process speed, process areas, hemisphere effect and difference components which were discuss in face recognize area also were explored in this thesis. The results indicate that, special components of face which included N170, VPP, and the later P200, N270, LPC were found in the ERP waves of both face expressions. In 450-850ms, there was difference between the late component caused by positive expression and caused by negative expression. There was hemisphere difference in the ERP wave of negative expression.3. First step study for Face orientationsERPs study of Face orientations which compared with ERPs of face inversion was carried on. Results show amplitude of N170 would decrease with the increase of face orientation but the latency showed the different situation in different brain areas. There were differences between the process of side face and face inversion.