You think your tastes are your own, but it may actually be that a hormone is making members of a group share the same preferences.
PROBLEM: Oxytocin, which you may also know as "the hormone of love," is the driving force behind sociability, trust, and generosity. It enables everything from mother-child bonding to orgasms, and it's one of the main things that sociopaths lack. The catch is that it strictly promotes in-group love -- and so it can't be used to kumbaya away cultural and political conflicts. Since oxytocin causes favoritism, might it also contribute to group conformity?
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METHODOLOGY: You can get oxytocin release by shaking someone's hand or hugging a loved one. But for the sake of standardization (and because you can't fake a hug), researchers administered the hormone via nasal spray to 34 subjects and a placebo to 35 others. The men participated in unrelated busywork until the oxytocin kicked in, at which point they were asked to rate symbols on an attractiveness scale of 1 to 11. ("These go to eleven.")
As they did so, they were shown everyone else's responses, including those of the other members of their randomly-determined "group." To ensure that people weren't trying to win social favor by agreeing with others in their group, the participants were not aware of one another's identities.
RESULTS: Barring the chance that some of the symbols were inherently more attractive than others, the subjects demonstrated a general tendency to conform to other people's opinions: oxytocin or not, they gave significantly higher ratings to symbols that other participants also liked, and vice-versa. But in cases where one's group liked a symbol and "outsiders" didn't, the subjects doped with oxytocin trended toward their group members' ratings. This held regardless of how many favorable or disfavorable opinions they saw before passing their own judgment and was not observed in the placebo group.
CONCLUSION: Oxytocin stimulates in-group conformity -- to the extent that subjective preference is influenced by horde mentality.
IMPLICATIONS: Oxytocin's effects were context-dependent, only causing conformity when the in-group's opinion was opposed to the out-group's. It may be that the hormone promotes in-group identification through shared biases, suggest the authors, ultimately functioning in the same way that team uniforms or gang colors do "to signal group membership and establish intergroup differentiation."
The full study, "The Herding Hormone; Oxytocin Stimulates In-Group Conformity," will be published in the journal Psychological Science.