The role of the chemical oxytocin in promoting social trust has been highlighted in many popular books and articles. Recent research suggests however that oxytocin also has a “dark” side. Its effect is not only to promote trust and cooperation among in-group members but also to engender betrayal and derogation towards out-group individuals. The two effects seem to be inextricably intertwined and depend on each other. This finding, that the mechanism of trust requires the exclusion of an other, is very important for understanding the current global political climate.
The joys and praises of oxytocin have been sung in many popular books. The Swedish author Kerstin Uvnäs-Moberg has written several books on the subject, such as The Oxytocin Factor: Tapping The Hormone Of Calm, Love, And Healing, and other popular authors on the topic include Kenneth Stoller and Susan Kuchinskas. In many such popular books the tone is rather breathless and authors seem to suggest that oxytocin is a sort of natural wonder chemical that promotes calm and love, banishes fear, and strengthens connections and intimacy.
It has also been proposed that oxytocin plays a key role in economic exchanges and in politics by increasing social trust in human communities. One of the first scholarly articles that suggested this was published in Nature in 2005, and was written by a University of Zurich research team that included both economists and psychologists. They pointed out that oxytocin may provide a biological basis of trust and prosociality among humans. Since this early work, other researchers in the newly emerging field of “neuroeconomics” have studied the effect of oxytocin on human prosociality. Paul Zak, of the Claremont Graduate School, and one of the authors of the 2005 Nature article has published a number of papers that explore the role of oxytocin in engendering trust and generosity.
A different line of research was initiated by the Dutch psychologist CKW De Dreu and his colleagues at the University of Amsterdam. In a paper published in 2011 in the Proceedings of the National Academy of Sciences, they reported the results of a very interesting set of experiments using Dutch males as subjects. The first two experiments tested the implicit association of in-group Dutch names and out-group German and Muslim names with positive and negative traits. The effects of intranasal oxytocin were found to be significant for in-group favouritism, and borderline significant for out-group derogation. In the third experiment the subjects were tested for their association of primary and secondary emotions to Dutch and Muslim targets. Significant effects of oxytocin were found for both in-group favouritism and out-group derogation.
The most interesting De Dreu experiments were the fourth and fifth ones. In these, the subjects carried out five different Moral Choice Dilemma including the famous trolley problem, where the subject has to decide whether to divert a runaway trolley to save five innocent victims when the diversion costs the life of another innocent. When the target victim’s name was randomly varied between a typically Dutch or a Muslim name, it was found that oxytocin significantly increased the sacrifice rate of the target when he had a Muslim rather than a Dutch name.
Since this early study the Amsterdam group has further explored various aspects of the phenomenon they call “parochial ethnocentrism” and its link with the chemical oxytocin. Out-group derogation is central to the mechanism of creating in-group trust and cooperation and is not an incidental by-product. As De Dreu et al write
A key mechanism facilitating (such) in-group cooperation is ethnocentrism, the tendency to view one’s own group as centrally important and as superior to other groups. Ethnocentrism manifests itself in positive valuation of (members of) one’s in-group. Such in-group favoritism signals loyalty and positive commitment to the group, thus rendering the ethnocentric individual a reliable and trustworthy partner. Ethnocentrism may also show up in negative valuation of (members of) out-groups. Such out-group derogation signals to in-group members who should be excluded from in-group resources and exchanges, and reduces the probability that in-group resources are inadvertently extended to out-groups
This is an essential insight for understanding the motivation of political actors and especially of the “populist and nationalist” brand of politics that is ascendant in much of the world today.