Oxytocin’s Dark Side

Flickr photo by ani-bee

We’ve written earlier on research that suggests that oxytocin, the same hormone that is produced by mothers nursing their young or through sexual intercourse, plays a pivotal role in trust.

Recent research, published in Science last year and recently in PNAS indicates that oxytocin has a dark side.  It doesn’t promote trust of everyone but strengthens “in group trust” and decreases “out group trust”.

Excerpt from NY Times article on the research:

With a new set of experiments in Tuesday’s issue of the Proceedings of the National Academy of Sciences, he has extended his study to ethnic attitudes, using Muslims and Germans as the out-groups for his subjects, Dutch college students.

These nationalities were chosen because of a 2005 poll that showed that 51 percent of Dutch citizens held unfavorable opinions about Muslims, and other surveys that Germans, although seen by the Dutch as less threatening, were nevertheless regarded as “aggressive, arrogant and cold.”

Well-socialized Dutch students might be unlikely to say anything derogatory about other groups. So one set of Dr. [Carsten] De Dreu’s experiments tapped into the unconscious mind by asking subjects simply to press a key when shown a pair of words. One word had either positive or negative connotations. The other was either a common Dutch first name like Peter, or an out-group name, like Markus or Helmut for the Germans, and Ahmad or Youssef for the Muslims.

What is measured is the length of time a subject takes to press a key. If both words have the same emotional value, the subject will press the key more quickly than if the emotional overtones conflict and the mind takes longer to reach a decision. Subjects who had sniffed a dose of oxytocin 40 minutes earlier were significantly more likely to favor the in-group, Dr. De Dreu reported.

In another set of experiments the Dutch students were given standard moral dilemmas in which a choice must be made about whether to help a person onto an overloaded lifeboat, thereby drowning the five already there, or saving five people in the path of a train by throwing a bystander onto the tracks.

In Dr. De Dreu’s experiments, the five people who might be saved were nameless, but the sacrificial victim had either a Dutch or a Muslim name. Subjects who had taken oxytocin were far more likely to sacrifice the Muhammads than the Maartens.

Dr. De Dreu believes that all group association spurs oxytocin, and it is no more likely to be formed through religious groups than through soccer associations, military units or PTA groups.   This rise of oxytocin doesn’t occur in a vaccuum: Bruno B. Averbeck, an expert on brain emotional cognition at the National Institute of Mental Health, says that the brain weighs rational data against the emotional impact of oxytocin.

Read “Depth of the Kindness Hormone Appears to Know Some Bounds” (NY Times, Science Times, January 11, 2011, by Nicholas Wade)

Read “Oxytocin Promotes Human Ethnocentrism” (PNAS, Jan. 10, 2011) by Carsten K. W. De Dreu, Lindred L. Greer, Gerben A. Van Kleef, Shaul Shalvi and Michel J. J. Handgraaf.


2 responses to “Oxytocin’s Dark Side

  1. No proof that oxytocin triggers ethnocentrism

    In an intriguing paper, De Dreu et al. (1) claim that oxytocin, sometimes called the “love hormone”, promotes human ethnocentrism. They conclude that “oxytocin functions to strengthen an evolutionary evolved and rather functional tendency to discriminate between in-group and out-group as well as to give members of one’s own group preferential treatment”. As sociologists we do not see the added value of speculation on the evolutionary basis of ethnocentrism. Furthermore, it needs to be stressed that in-groups and out-groups are not clearly delineated natural entities but social constructions, which –as the phenomenon of ethnocentrism itself- cannot be adequately analyzed without taking into account social networks and power constellations.

    Let us, however, focus on the empirical finding – even though flirting with statistical significance – of the double blind experiments that brain oxytocin seems to stimulate in-group favoritism (which is not the same as ethnocentrism (2), a concept that combines in-group favoritism with out-group derogation).

    Let us first of all note that the effects might be statistically significant but that they are not very strong. Oxytocin’s role in stimulating in-group favoritism will be minor compared to other factors (mainly social ones). There are, however, also issues of internal and external validity. What is really being measured here? Results of an Implicit Association Test, as used in the article, might just as well be due to differences in name familiarity or in-group/out-group status (3). The authors too quickly rule out these alternative interpretations and the experiments would have been more convincing if they also undertook an outgroup-outgroup IAT (German-Arab). We are also worried about potential confounding variables. In between experiments, the authors administered questionnaires on political values and opinions. We hope that adequate analysis was undertaken with regard to socio-demographic characteristics and attitudes of respondents who were respectively assigned to the experimental and control group, as these are important explanatory factors for in-group favoritism and out-group derogation (4).

    Furthermore, what is the external validity of these tests? How should these findings be transposed to social interactions outside of the laboratory? In real life, social networks can be mixed and in-group/out-group classifications are dynamic. What would the results look like if cross-ethnic friendship ties were taken into account? In-groups are not homogeneous natural entities, as the authors seem to presuppose.

    Oxytocin seems to have some effect in the experiments but the authors themselves show that it is not on ethnocentrism (as they do not find sufficient support for their hypotheses on out-group derogation). We hence do not understand why the title boldly states that oxytocin promotes ethnocentrism. It does not. Perhaps there is a small effect on in-group favoritism in an experimental setting, but what happens when people interact in real life?

    Dirk Jacobs, François Ghesquiere and Daniel Zamora
    Institut de Sociologie, Université Libre de Bruxelles, 44 Avenue Jeanne, 1050 Bruxelles, Belgium

    1. De Dreu C, Greer L, Van Kleef G, Shalvi S, Handgraaf M (2011) Oxytocin promotes human ethnocentrism. Proc Natl Acad Sci
    USA 2011 0: 1015316108v1-201015316.
    2. Hooghe M (2008) Ethnocentrism. International Encyclopedia of the Social Sciences. Philadelphia: MacMillan Reference.
    3. van Ravenzwaaij D, van der Maas H, Wagenmakers, E-J (2010) Does the Name-Race Implicit Association Test Measure Racial Prejudice? Exp Psychology 2010 Nov 24 (Epub ahead of print)
    4. Billiet J, Eisinga, R, Scheepers, P (1996) Ethnocentrism in the Low Countries: a comparative perspective. New Community 1996 22 (3): 401-416.

  2. It has been shown that their country’s bad attitude toward Muslims and Germans is fueled by the brain hormone, oxytocin. The researchers concluded this after having Dutch men inhale oxytocin or a placebo and complete a series of studies designed to measure social attraction and empathy. The subjects’ button-pushing response time was measured when presented with classic Dutch, German, or Arabic names paired with either positive or negative words. Next they had to select which of the names they would save versus sacrifice in hypothetical (and wildly improbable) life or death scenarios. When the subjects inhaled oxytocin, they quickly chose Dutch names linked with positive words and were most likely to sacrifice a Muslim or German named-character in favor of saving a group of Dutch-named people. The researchers conclude that oxytocin supports “in-group” fidelity and that their study, “calls into question the view of oxytocin as an indiscriminant love drug or cuddle chemical.”

    The thing is that no one has ever seriously suggested oxytocin’s social agenda was “indiscriminant.” Decades of animal and human studies found that oxytocin does indeed promote “selective” social bonds like those that make a mother sheep care only for her lamb, or those that inspire male and female prairie voles to mate for life. Such exclusive loyalties can make very good evolutionary sense, but a lot of the time a more inclusive social agenda is beneficial and oxytocin has been shown to be helpful there as well. With the aid of oxytocin, we can overcome the fear of novelty that might cause us to automatically reject unfamiliar people. This primal tolerance allows a new mother to instantly accept her newborn “stranger” as her own. It also encourages babies to seek and accept nurturance from other caregivers, urges us to mate with “outsiders” rather than kin, and is central to our ability to create the wide range of friendships and alliances–beyond our clans and even beyond our species–that made human civilization possible.

    Oxytocin manages to encourage this wide range of social flexibility by making us very good at evaluating verbal and non-verbal social signals. With the help of oxytocin, our brain’s fear and stress circuitry are suppressed enough for us to perceive a glint of friendship in an eye or tone of voice that encourages social approach. And when our encounters prove beneficial, it releases even more oxytocin in our brains tripping the reward circuitry which will help us remember those we can trust and urge us to connect with them again. This is called “social recognition” and under natural circumstances where adequate social stimuli are provided, it can support the oxytocin feedback system that creates a sense of trust and kinship far beyond tribe, nationality, or even species.

    The Dutch study appears to refute this, but they look at oxytocin’s behavior divorced from its social milieu. The subjects made their social preferences based only on people’s printed names. These abstract representations merely suggest nationality and gender and fail to provide the sort of non-verbal social information oxytocin is so good at parsing. So what did a nose full of oxytocin do with such limited social information? It may simply have heightened the Dutch men’s sense of recognition and attraction to names most similar to their own. If the experiments had asked their subjects to respond to pictures of Dutch, German, and Arab men making a variety of friendly and unfriendly facial expressions and found that oxytocin-treated Dutch men still favored frowning Dutch faces over smiling foreign ones, I think that would make a stronger case that oxytocin, is the “not-our-kind” hormone. It would also be surprising because other studies have found that inhaling oxytocin improves our social perception of strangers—even when those faces were paired with electric shock.

    While the researchers believe they’ve shown that oxytocin played an important evolutionary role in the “emergence of intergroup conflict and violence,” I would counter that the bulk of oxytocin research finds that it is not an agent of aggression and territoriality. In fact, it’s capable of making the sorts of social distinctions that help us override reflexive anti-social behavior–otherwise known as prejudice. And human history tells us somewhere, deep in our brains, cooperation trumped competition time and time again. After all, we were able to expand our social recognition to create new social kinships called “neighbors,” “citizens,” “livestock,” “pets.” It has been our ability to discriminate social intention that has allowed us to socialize “outside the clan,” and become the most successful social mammal on the planet. While our impressive frontal lobes helped, we still owe much of our social grace to oxytocin.
    – author of “Made for Each other, the Biology of the Human-Animal Bond” (Dacapo, 2009).

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