Oxytocin is a neurotransmitter that has been linked in a variety of studies to various activities such as fostering trust in relationships, social bonding, sexual pleasure, increased emotional comprehension, and mother-infant bonding. Its effects in these areas are fairly well-recognized; perform a Google search for “oxytocin” and immediately below the obligatory Wikipedia page you’ll find it described as the “hormone of love”, along with advertisements touting the various sprays and homeopathic remedies that promise to improve your relationships (read: sex lives). All of this attention, however, brings to mind a question: how much emphasis should we place on the role that hormones play in our decision-making processes?
Of primary discussion in this post will be a new study described by the New York Times linking exposure to oxytocin and increased intergroup bias. The study was authored by Carsten DeDrew, a psychologist at the University of Amsterdam, who was intrigued by the literature linking oxytocin to increased cooperation. He posited that evolutionary pressures would require that some sort of limit be placed on this relationship-building behavior, because unbounded trust would not increase chances of survival.
The in-group in this experiment was Dutch college students, and the out-groups were Germans and Muslims, based on data showing that many Dutch citizens had negative opinions of those two groups. Ed Yong on Discover Magazine’s blog describes how, in several double-blind experiments, students were given nasal spray with either oxytocin or a placebo, and then took an implicit association test asking them to categorize words into different groups. Biases in such studies are found in reaction times, and the data showed that those who had taken doses of oxytocin were quicker to associate positive words with Dutch names like Peter than with a common Muslim name such as Youssef. The second study, similar to the modified trolley dilemma described by Knowles, asked students to make moral choices: one involved a train where a flipped switch would save five people on the tracks but kill one, while another involved deciding whether to help someone onto a lifeboat if it meant drowning the other five passengers. In each case, the single person was given a Dutch, German, or Arab name, while the ethnic identity of the larger group to be saved was not implied in any way. The results showed that the participants who had been exposed to oxytocin were less willing to sacrifice the individuals with Dutch names. Thus, oxytocin can be seen to strengthen in-group bonds by giving members of your own community preferential treatment, while mistrusting perceived outsiders. Ed Yong describes the implications of this work in this way:
The stereotypical view of oxytocin is that it increases positive feelings rather than negative ones. But it doesn’t do so equally. Rather than being an all-purpose chemical of social affection, you could view oxytocin as a drug that strengthens our tendency to discriminate between people within and outside our social cliques. “Different” can come under many guises – in de Dreu’s experiments, Germans and Arab people were both treated as outsiders, despite having very different characteristics and stereotypes.
The New York Times quotes Dr. DeDrew’s analysis of why this result comports with expectations of evolutionarily advantageous behavior:
In the ancestral environment it was very important for people to detect in others whether they had a long-term commitment to the group… Ethnocentrism is a very basic part of humans, and it’s not something we can change by education.
A larger question, however, posed by Swedish neuroscientist Daniel Ocampo Daza, is the extent to which
we can depend on studies like these to show that hormones actually determine a particular behavior absent additional context. Is ethnocentric behavior completely fixed by our biology? Daza wants to advocate for a more nuanced view of implications of this study:
It’s possible to say that oxytocin is implicated in ethnocentrism, but it’s difficult to say exactly under which conditions or in which situations outside of these experiments, or if it sometimes is overridden or reinforced by other neural substrates. The brain is complex enough to make it safe to assume that oxytocin probably isn’t acting alone.
It is interesting to think about the possibility that our hormones somehow foster ethnocentrism in combination with Knowles’ description of the debate between intuitionism and casuistic reasoning. How and why does a particular group become defined? What role does biology and evolutionary wiring play in determining what we choose to believe, or why we develop particular emotions, beliefs, and structures of reasoning? Knowles clearly documented certain biases in particular groups, using particular beliefs held by conservatives and liberals to document that “our judgments are biased by our preferences.” How did these concerns about fairness come to be preferred by some members of the community, while others (conservatives) decided to prioritize in-group loyalty? The theory of flexibility of principle and preference, and the idea that “moral intuitions reflect adaptive insights,” can be informed by studies about biological mechanisms like oxytocin. Maybe one day, when we recognize all of the variables, we’ll actually understand what’s happening inside our heads.