In the present study, investigator plan to use a double-blind, between-subject placebo controlled design.Firstly, all healthy male subjects' autistic trait levels will be assessed by the Autism Spectrum Quotient (ASQ) and only subjects with higher or lower ASQ score will be recruited in the next experiment and divided into high and low subgroup. Then, subjects are randomly assigned to receive either intranasal administration of oxytocin (24 IU) or placebo. 45 min later, subject need to complete an attentional bias task named rapid serial visual presentation (RSVP) task in fMRI scanner.