pnas | Human ethnocentrism—the tendency to view one's group as centrally
important and superior to other groups—creates intergroup
bias that fuels prejudice, xenophobia, and
intergroup violence. Grounded in the idea that ethnocentrism also
facilitates within-group
trust, cooperation, and coordination, we conjecture
that ethnocentrism may be modulated by brain oxytocin, a peptide shown
to promote cooperation among in-group members. In
double-blind, placebo-controlled designs, males self-administered
oxytocin
or placebo and privately performed computer-guided
tasks to gauge different manifestations of ethnocentric in-group
favoritism
as well as out-group derogation. Experiments 1 and 2
used the Implicit Association Test to assess in-group favoritism and
out-group derogation. Experiment 3 used the
infrahumanization task to assess the extent to which humans ascribe
secondary,
uniquely human emotions to their in-group and to an
out-group. Experiments 4 and 5 confronted participants with the option
to save the life of a larger collective by
sacrificing one individual, nominated as in-group or as out-group.
Results show
that oxytocin creates intergroup bias because
oxytocin motivates in-group favoritism and, to a lesser extent,
out-group derogation.
These findings call into question the view of
oxytocin as an indiscriminate “love drug” or “cuddle chemical” and
suggest that
oxytocin has a role in the emergence of intergroup
conflict and violence.
