People often conform to others with whom they associate. Surprisingly, however, little is known about the possible hormonal mechanisms that may underlie in-group conformity. Here, we examined whether conformity toward one's in-group is altered by oxytocin, a neuropeptide often implicated in social behavior. After administration of either oxytocin or a placebo, participants were asked to provide attractiveness ratings of unfamiliar visual stimuli. While viewing each stimulus, participants were shown ratings of that stimulus provided by both in-group and out-group members. Results demonstrated that on trials in which the ratings of the in-group and out-group were incongruent, the ratings of participants given oxytocin conformed to the ratings of their in-group but not of their out-group. Participants given a placebo did not show this in-group bias. These findings indicate that administration of oxytocin can influence subjective preferences, and they support the view that oxytocin's effects on social behavior are context dependent.

decision making, judgment, neuroendocrinology, social behavior, social influences
dx.doi.org/10.1177/0956797612446026, hdl.handle.net/1765/38052
Psychological Science
Includes both the penultimate version of September 18, 2012 and the final VOR of November 13, 2012
Erasmus Research Institute of Management

Stallen, M, de Dreu, C.K.W, Shalvi, S, Smidts, A, & Sanfey, A.G. (2012). The Herding Hormone: Oxytocin Stimulates In-Group Conformity. Psychological Science, 23(11), 1288–1292. doi:10.1177/0956797612446026