Data for: The Effect of Oxytocin on Group Formation and Strategic Thinking in Men

Abstract
Decision-making in groups is a remarkable and decisive element of human societies. Humans
are able to organize themselves in groups, engage in collaborative decision-making processes
and arrive at a binding agreement, even in the absence of unanimous consent. However, the
transfer of decision-making autonomy requires a willingness to deliberately expose oneself to
the decisions of others. A lack of trust in the abilities of others or of the underlying decisionmaking
process, i.e. public trust, can lead to a breakdown of organizations in political or
economic domains. Recent studies indicate that the biological basis of trust on an individual
level is related to Oxytocin, an endogenous neuropeptide and hormone, which is also associated
with pro-social behavior and positive conflict resolution. However, little is known about the
effects of Oxytocin on the inclination of individuals to form or join groups and to deliberately
engage in collaborative decision-making processes. Here, we show that intranasal
administration of Oxytocin (n = 60) compared to placebo (n = 60) in males causes an adverse
effect on the choice for forming groups in the presence of a competitive environment. In
particular, Oxytocin negatively affects the willingness to work collaboratively in a p-Beauty
contest game, whereas the effect is most pronounced for participants with relatively high
strategic sophistication. Since our data provide initial evidence that Oxytocin has a positive
effect on strategic thinking and performance in the p-Beauty contest game, we argue that the
adverse effect on group formation might be rooted in an enhanced strategic sophistication of
participants treated with Oxytocin.