The project has three overall objectives. The first is to determine whether and how administration of intranasal oxytocin (OT) and intranasal vasopressin (AVP) influence cooperative decision-making and neural responses to cooperative and un-cooperative social interactions. The second is to determine whether and how intranasal vasopressin influences subjective evaluations of and neural responses to same and opposite-sex face stimuli and to determine if any of these effects persist beyond the period of AVP exposure. The third objective is to determine if intranasal OT influences empathy-related behavior and associated brain activity.