The Effect Of Context Information On Facial Evaluation

Human faces give a large amount of social information,thus become one of the most important platform of our social interactions.Traditional research on face processing mainly focuses on identity recognition,facial expression processing,and so on.However,in daily life,humans evaluate a person’s personality traits through the analysis of his or her face so unconsciously and routinely.For example,whether a person is considered to be trusted,or is competitive.Thus there is an open question that how personality traits are extracted from faces.Neuroimaging studies have shown that reward-related brain areas,are involved in trait evaluation such as facial attractiveness,personal responsibility.However,previous neuroimaging studies on human faces failed to explore the time course of trait evaluation from faces because of temporal limitations.Therefore,the aim of the present study is to explore the temporal features of processing faces by using the high temporal resolution of ERPs while participants perform a series of trust game task.Taken together,the findings of the current study are presented as follows:(1)Under different trust evaluation conditions(direct VS.indirect).Larger N170 amplitudes were elicited in the indirect evaluation condition than in the direct condition,but there were no late positive potential(LPP)amplitude differences between the two conditions.Moreover,the peak latency of LPP was shorter in the indirect evaluation condition than in the direct condition.These findings suggested that trust ’evaluation tasks(direct VS.indirect)did not modulate the later stage of face processing,but indirect task were relatively easy.(2)Under different social trait evaluation tasks,face stimuli elicited LPP amplitudes in the social trait evaluation task than in the no-social trait evaluation task,and no differences were found in related-brain areas.The results suggested faces captured more attention in the social trait evaluation task.Meanwhile,there were no differences between the two tasks when different faces were evaluated.(3)The presence of context information affects facial trust evaluation in postphase of encoding cognition.Research results showed identity information affected facial trust evaluation and play its role in LPP(target stimulus presented for between 400-800ms).Specifically,average LPP wave induced by facial evaluation without identity information reminding was significantly greater than that with identity information.Rate of choosing opening door for groups with identity information was significant higher than that of groups without identity information.These findings suggest that context information affects facial trust evaluation and saved the investment of attention resources.(4)Different context information have different effects on facial trust evaluation.Research results revealed that various context information influenced facial trust evaluation and reflected the difference of LPP.Specifically,context information affected the choice rate and reaction time of facial trust evaluation.Trust choice rate under nonsocial condition was slightly higher than under social condition.Self-oriented trust choice rate was significantly higher than other-oriented trust choice rate.Trusted choice reaction time was significantly longer than mistrust choice reaction time.Different social context information influenced average LPP wave but had no effect on N170 and other early ingredients.The average LPP wave induced by social context information in the process of facial trust evaluation was significantly higher than nonsocial context information.