Study Suggests Oxytocin Makes People Trusting, but Not Gullible

Oxytocin (OT) is a hormone that plays an important role in social behavior—it has even been nicknamed “the love hormone” and “liquid trust.” Increased levels of OT have been associated with greater caring, generosity, and trust. But does OT increase people’s trust in just anybody or does it act more selectively?

Psychological scientist Moïra Mikolajczak from the Université catholique de Louvain (Belgium) and her colleagues investigated just how trusting OT can make us. In this experiment, volunteers received either a placebo or OT nasal spray. Then, they played a trust game in which they received a certain amount of money which they could share with a partner (any amount shared with the partner would then triple). The partner then decides what to do the money—they can keep it all for themselves or split the amount with the giver. If the volunteer is trusting, they will share more money with their partner (in the hopes of having some of it returned to them) than volunteers who are not as trusting. The participants played the trust game against a computer and virtual partners (which were supposedly in another room), some of whom appeared reliable (they seemed likely to share the money with the participants) and some of whom appeared unreliable (they seemed likely to keep the money for themselves).

The results, reported in Psychological Science, a journal of the Association for Psychological Science, showed that volunteers who received the OT nasal spray were more trusting of the computer and the reliable partners—that is, they offered more money to the computer and the reliable partner than did volunteers who received the placebo nasal spray. However, OT did not have an effect when it came to sharing with a seemingly unreliable partner—the volunteers were not generous towards a potentially unreliable partner, regardless of which nasal spray they received.

These findings suggest that OT fosters trust, but not gullibility: OT may make individuals more trusting, but only in certain situations. The authors conclude that “oxytocin is not the magical ‘trust elixir’ described in the news, on the Internet, or even by some influential researchers.”