| Face processing is one of the most important social and biological functionstudied in cognitive neuroscience, a face can reveal an enormous range of sociallyrelevant information. For example, an observer may derive a person’s identity, gender,age and emotional state from the face.Accounting to Bruce and Young’s (1986) model of face recognition and Thedistributed human neural system for face perception facial expression and gender areanalyzed within mutually independent processing routes, and also have a relativelyindependent brain regions. From the evolutionary psychological perspective, the rapidprocessing of emotional information and gender information are both necessary forhuman survival. So it is meaningful to compare the two processes. the previousstudies always compare the time course of facial gender and expression processing isthat they have focused on relative timing differences between different facecategorization tasks(gender task and expression task). In real life, however, the twokinds of information are in free competition in many conditions, which no sign ofclear indication is showed to process one of them firstly.so we used the same-differentParadigm (experiment1)and oddball Paradigm(experiment2/3) to research thequestion. In experiment1subjects are showed2facial pictures simultaneously, thepictures are the same in both gender and expression dimension or difference in onedimension or two dimensions. The same condition is defined as both the dimensionsare the same and different conditions includes three kinds of situations: the expressionis different (ED), gender is different (SD), both are different (D).In Experiment2,3subjects were asked to response to one type of the combination information ofexpression and gender (e.g. male crying, target stimulus types are balanced betweensubjects), other combinations were not reaction, so the Nogo conditions includes3situations: the sex is different from the target(SD),the expression is different from thetarget(ED),both the sex and expression are different from the target(D). experiments3is the same as experiment2except the removal of D conditions, while the ED andSD(1204ms) conditions are presented in blocks to explore the influence of attention.Results:（1）in Experiment1reaction time of D(1158ms) condition wassignificantly shorter than the ED(121), SD conditions(1204), the ACC of ED(91.6)was significantly higher than that of SD condition(85.8)（.2）Experiment2:Just3Nogoconditions were analysied and there were no difference in N170, but the no-go LRPonly present in the condition SD.Results obtained from the analyses of P3a suggestthat the main effect of stimulus type is significant. F(2,40)=5.232, p=.01,2=0.207.Amplitude of SD (1.797uV)is lower than ED（2.316uV）and D（2.24uV）condition, p<.05,and there is no difference between ED and SD condition,(p＞.05).(3)InExperiment3, the amplitude of ED was still significantly larger than SD, but therewere no significant differences in latency.Conclusion: in experiment1, because the conditions of reaction time was shorterthan ED and SD, we can infer that priority of expression and gender is in probability,sometimes the facial expression will be finished firstly, and sometimes the facialgender will. And and the ACC of ED condition was higher than SD. It is indicated thatthe expression processing may catch more attention than the gender processing tosome extent. The result of experiment3illustrate the advantage of expression in speedwill disappear in the situation with abound attention resource. So the genderprocessing may depend on more attention than the expression. |
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