A Thin Line Between Love And Hate… In Your Brain

We are all familiar with the fuzzy feelings that accompany falling in love. You and your partner become emotionally connected, supported, and complete. Although human love is a complicated and long journey, scientists consistently find that the release of a specific neuropetide—oxytocin—may kick start these feelings right away in courtship. In fact, for the past few decades researchers have referred to oxytocin as the “love hormone,” and credit its release as the glue that ties humans to their loved ones.

Oxytocin’s cupid effect is not specific to romantic love, but rather various forms of pro-sociality. Pregnancy and labor are times when a woman naturally experiences surges of oxytocin, which may facilitate mother-infant bonding. In males, administering oxytocin has been shown to increase trust, understanding, and even enhance empathy in males with social deficits. Nonetheless, oxytocin is best known for keeping us monogamous, or “pair bonded” as the scientists say.

But is oxytocin really the saccharine drizzled on social life? Recent findings suggest not. While oxytocin may enhance positive emotions and pro-sociality with the people we care about, it may also contribute to negative views and behaviors towards people to whom we are not close. Research in social psychology finds that humans simultaneously show favoritism for the people in their social circle (“ingroup”) and derogation of people in social groups that are different from their own (“outgroup”). Although not conclusive, recent findings suggest that administering oxytocin to males not only enhances their in-group favoritism, but in some cases, also increases defensiveness towards outgroup members.

Given the atrocities that can result from ethnocentricity, the suggestion that oxytocin could increase an ingroup bias calls into question whether oxytocin is really the brain’s warm and fuzzy cuddle chemical. When it comes to oxytocin, does a rose by any other name really smell as sweet?


Kosfeld, M., Heinrichs, M., Zak, P., Fischbacher, U., & Fehr, E. (2005). Oxytocin increases trust in humans Nature, 435 (7042), 673-676 DOI: 10.1038/nature03701

Bartz, J., Zaki, J., Bolger, N., Hollander, E., Ludwig, N., Kolevzon, A., & Ochsner, K. (2010). Oxytocin Selectively Improves Empathic Accuracy Psychological Science, 21 (10), 1426-1428 DOI: 10.1177/0956797610383439

De Dreu, C., Greer, L., Handgraaf, M., Shalvi, S., Van Kleef, G., Baas, M., Ten Velden, F., Van Dijk, E., & Feith, S. (2010). The Neuropeptide Oxytocin Regulates Parochial Altruism in Intergroup Conflict Among Humans Science, 328 (5984), 1408-1411 DOI: 10.1126/science.1189047

De Dreu, C., Greer, L., Van Kleef, G., Shalvi, S., & Handgraaf, M. (2011). Oxytocin promotes human ethnocentrism Proceedings of the National Academy of Sciences, 108 (4), 1262-1266 DOI: 10.1073/pnas.1015316108

Meghan Meyer, PhD (c)

Meghan Meyer, PhD candidate, studies social cognitive neuroscience at University of California-Los Angeles. Prior to joining UCLA, she worked on behavioral and brain imaging studies in the Stanford University Cognitive and Systems Neuroscience Lab and the Social Cognitive Neuroscience Lab at the University of Chicago, and completed her M.A. in cognitive science, with a specialty in cognitive neuroscience, from Ecole Normale Superieur, in Paris, France. When she is not in the lab designing studies and analyzing data, she enjoys writing about scientific findings and their broader impact for general audiences.
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