In a recent study, oxytocin levels in single individuals and romantic couples were measured, and the couples were videotaped while interacting with each other. Individuals in romantic relationships were found to have higher levels of oxytocin than the romantically-unattached. Further, couples with the highest oxytocin levels were more likely to experience positive emotions when interacting with their partners. This research provides additional evidence of the critical role of oxytocin in promoting bonding between individuals.
Schneiderman, I., Zagoory-Sharon, O., Leckman, J. F., & Feldman, R. (in press) Oxytocin during the initial stages of romantic attachment: Relations to couples’ interactive reciprocity. Psychoneuroendocrinology. doi:10.1016/j.psyneuen.2011.12.021