Neurobiological Bases of Paternal Nurturance

30 fathers of children aged 1-3 will participate in two functional imaging sequence (fMRI) sessions, once under the influence of OT/AVP, and once under the influence of placebo. Fathers will be restricted to men who are living with their biological child and an adult partner (male or female) that they are in a committed relationship with. All fathers will receive two fMRI scans on two different occasions, separated by 2-10 days. 15 fathers will be randomized to intranasal OT, the other 15 will be randomized to intranasal AVP. Within each drug group, the order of administration of drug and placebo will counterbalanced across subjects, such that 15 will receive OT/AVP first, and 15 will receive OT/AVP second. During the fMRI scans, fathers will view pictures of their own and unknown children, as well as unknown adults. Afterwards, while still in the scanner, they will listen to infant cry and control stimuli. After exiting the scanner, fathers will again listen to the cry stimuli and will rate their emotional reaction to the cry stimuli on the following dimensions using a 7 point likert scale: irritated, sympathetic, alarmed, angry, upset, compassionate, distressed, annoyed, and tender.