When someone says "I do" at a marriage ceremony, they are committing themselves to a long-term relationship. We call this EARLY-STAGE COMMITTMENT. They have probably gotten beyond EARLY-STAGE ROMANCE. What could be going on in their brains? What does commitment mean in terms of brain physiology?
For the group of 19 people (11 women) scanned and interviewed by Bianca Acevedo, when they looked at a picture of their newlywed marriage partner it meant:
1) Some infatuation, still
2) Attachment system activation at the unconscious level, using brain areas that have dopamine, oxytocin and vasopressin receptors. These systems are used by other mammals for attaching to a partner.
3) Deactivation of brain areas that we use to judge others (!) It looks like the brain is suspending judgment of the partner. That can be a very good thing for the relationship. We need "positive illusions" about our partner. We need to think they are the greatest, even if we know they have faults.
4) Activation of areas that we use for cognitive control of emotions. This is important when you are in a relationship.
5) Some activation of hormonal regions that may reduce feelings of stress.
6) Some deactivations that suggest incorporation of the other person into a sense of our own selves, even at the level of our own bodies. The other person becomes part of our sense of "self."