Its very essential to understand others subjective experiences and to react properly.Such ability,commonly known as empathy,plays a vital role in everyones daily life.It may well be this capacity that helps people to connect closely and to form social groups.Pain ranks one of the most intensive emotional experiences,and accurately perceiving others pain benefits both the sufferer(e.g.,getting social support)and the observer(e.g.,judging the threat of the environment).Previous research demonstrate neural overlap between first-hand pain and vicarious experience of pain.As yet,however,no studies concerns how and when people differentiate others real pain from faked pain.The present study focused on the above-mentioned problem by using the event-related potential approach.A 2×3 within-subject factorial design was used for the present experiment,with the first factor being the pain condition(pain vs.no pain),and the second factor being the stimulus category(expression,face,and arm).Accordingly,there were six types of stimuli,i.e.,painful expression,neutral expression,needle penetrated face,q-tip touched face,needle penetrated arm,and q-tip touched arm.Thirty-one healthy Chinese college students participated in the experiment(male/female: 13/18,age 21.90±1.90).They watched 900 pictures while their scalp EEG were monitored and recorded by a 64-channels BioSemi ActiveTwo system.Raw EEG data were preprocessed and then averaged across conditions.Afterwards,a two-step principle components analysis(PCA)method was conducted to determine the ERP differences.The grand-averaged ERPs data showed pain empathic ERP components(N1,VPP,N2 and LPP over fronto-central electrodes; P1,N170 over lateral-occipital area)for all kinds of stimuli.Painful pictures elicited positive shifts than neutral ones on the whole.The arm-locked ERPs displayed longer latency and lower amplitude as compared to the face-locked ERPs,mainly on the early components.These results are consistent with previous research.Besides,our data also revealed that participants sensed the deceitfulness of the needle-pricked neutral face condition from a very early time(approximately 200 ms from stimulus onset).The result suggests brain owes the sensitivity to the reality of others pain,which determines whether a proper act is taken or not.