The results of two recent studies suggest that researchers may have identified a biological basis of trusting behavior. Researchers from the University of Zurich and Claremont Graduate University in California administered either oxytocin, a hormone involved in nurturing behavior and social attachment, or a placebo to study participants. These participants, all male college students, then played a game where they assumed the role of either a monetary investor or a trustee. The rules of the game dictated that the more money investors shared with their trustee, the more they could receive in return. But they were also taking the risk that the trustee would abuse their trust and give them little to no return on their investment.
Previous research has shown that humans don’t like to place this kind of trust in others, especially strangers. But in this new study, investors who received oxytocin before the interaction displayed more trusting behavior than investors who had received the placebo, transferring larger amounts of money to their trustees. What’s more, oxytocin did not affect the amount of money trustees gave back to investors, suggesting that the behavioral change caused by oxytocin was specific to trusting behavior, not kind or generous behavior in general.
But couldn’t oxytocin have affected another aspect of the investors’ behavior, perhaps their willingness to take risks? In fact, the researchers also created a variation on their game, where they replaced the trustee participant with a method of randomly determining how much return investors would receive. In this second game, when there was no human partner toward whom they could feel trust, investors who had received oxytocin did not transfer any more money than did members of the placebo group. Thus it seems that oxytocin had a particular effect on the investors’ feelings toward another human, not simply on their tolerance for risk.
The authors say that their findings could have far-reaching implications for the treatment of social phobias. Such conditions are often characterized by a persistent fear of social interaction and can result in severely impaired daily functioning, and even increased suicide risk. More than financial investors or trustees, perhaps it will be people with these conditions who benefit most from the new science of trust.