Oxytocin has been the focus of a lot of research
lately. Oxytocin is a hormone that is
released when people touch or kiss. It
is also released during orgasm, during childbirth, and during
breastfeeding. In the body, oxytocin creates
muscle contractions and it also plays a role in the reflex that causes milk to
be let down in nursing mothers. Oxytocin
also acts on the brain, and that has been the source of a lot of research. Various popular accounts have called oxytocin
a trust chemical or a love chemical.
The reality is more complex.
A nice demonstration of this complexity comes from a study in the
December, 2012 issue of Psychological
Science by Mirre Stallen, Carsten De Dreu, Shaul Shalvi, Ale Smidts, and
Alan Sanfey. These researchers focused
on the influence of oxytocin on people’s preferences for new objects.
Groups of six participants were brought to the lab where
they were administered oxytocin or a placebo using a nasal spray. Participants were each seated in front of a
computer, and they did about 40 minutes of filler tasks to allow the oxytocin
to have its effect. Then, participants
were informed that the group was divided into two teams. Each participant saw a series of novel icons
and were asked to rate how much they liked them. At the bottom of the screen, they could see
ratings that they believed were given by other participants. (In fact, the ratings were generated by the
experimenters.) They could see whether
the ratings came from members of their team or members of the other team.
If oxytocin just increases overall trust, then we would
expect that people who are given oxytocin would give preference ratings that
are more similar to the other ratings of all of the participants. However, the researchers suggested that
oxytocin may have a more specific effect.
It might increase people’s tendency to conform to the ideals of other
members of their own social group. In
that case, we would expect that people’s ratings would track those of other
members of the same team.
To provide a critical test of this possibility, on a certain
number of trials, the icons got divergent ratings from the participant’s team
members and the other team. Sometimes
the team members gave the icon a high preference rating while the other team
gave it low ratings and sometimes the opposite occurred.
On these trials, participants who got the placebo were
relatively uninfluenced by ratings of their team members. However, the participants who got oxytocin
gave significantly higher ratings when their team members also gave the icon a
high rating than when they gave it a low rating.
This result suggests that oxytocin increases people’s sense
of closeness to their social group (even when that social group is arbitrarily
created in the lab). This closeness
leads people to generate attitudes that conform to those of their group
members. However, it does not increase
general trust of all people. The
attitudes of people from other groups do not influence their behavior.
