Trust between people is essential to consolidate human societies. Trust is necessary both to make friends, form couples, families and organizations and of course it plays an essential role in economic exchanges and in politics. In the absence of trust between people and companies, market transactions are cut off, and in the absence of trust in the institutions and leaders of a country, political legitimacy is lost.
Most recent evidence indicates that trust among fellow citizens contributes to the economic, political, and social success of countries. However, little is known about the biological basis of trust between human beings. In nonhuman mammals, oxytocin plays a very important role in promoting positive social interactions. Oxytocin receptors are distributed in various brain regions associated with behavior, including mating, maternal care, sexual behavior, etc. In this way, oxytocin seems to allow certain animals to overcome their natural tendency to avoid proximity bonds, thus facilitating pro-social animal behaviors.
Based on this evidence in nonhuman mammals, Zak and his colleagues hypothesized that oxytocin could actually promote pro-social behaviors, such as trust, in humans. In this way, an experiment was carried out with two groups of people, one who received a single dose of oxytocin intranasally and the other to which a dose of placebo was administered, for control purposes.
The experiment itself was implemented through a game with real monetary payments (of the game theory type) to check if the intake of oxytocin increased the confidence of the participants or not. The game consisted of two groups of interacting subjects, one as an investor and the other as a trustee. First, those who acted as investors had the option to choose whether to transfer money (maximum 12 MUs - monetary units) to the trustees or not.
If the investor transferred, the trustee did not receive this amount, but triple it. And when the trustee was informed about the investor's decision to transfer or not, he could decide to honor the investor's trust by transferring money to him, but if he transferred, the investor did not triple, but received only the amount transferred by the trustee. But the trustee also had the option of violating the investor's trust, thus being a selfish trustee.
The investor in this game then faces a dilemma: if he trusts and transfers part or all of his money, and then the trustee decides to transfer part as well, the investor increases his final amount available; But there is also the risk that the trustee will abuse your trust and transfer little or nothing. That is, the investor faces the risk of trusting and not being reciprocated, as happens in hundreds of economic exchanges in reality.
The experiment, in this way, tries to find out if the investors of the oxytocin group (those who receive a previous intake of oxytocin via the nasal route) increase their transfers above what those of the placebo group do (those who only receive a previous intake of placebo via nasal route), thus overcoming, thanks to the administered oxytocin, the natural aversion to human risk.
And the result confirms the hypothesis - of Zak and his collaborators - prior to the experiment: the oxytocin group of investors ends up making larger average transfers, notoriously above the investors of the placebo group.
But the question of the influence of oxytocin on trust among humans has a finer edge: does oxytocin help to overcome human aversion to risk in general and in all kinds of situations, or does it only help to overcome it when it is necessary to decide on an environment of social interactions? To test this last effect, Zak and his collaborators slightly varied the experiment, and instead of allowing the interaction between investors and human trustees, now the decision of the trustees was made through a random statistical mechanism, totally impersonal. And in this variant of the experiment, the investors in the oxytocin group did not differ from those in the placebo group, suggesting that oxytocin specifically affects trust only in personal interactions.
Until now, the results found for the behavior of investors have been discussed. But when the case of the behavior of the trustees was analyzed, something interesting was seen: contrary to what had been expected, no greater transfers were observed from the trustees of the oxytocin group with respect to those of the placebo group, confirming that oxytocin it does not generally increase the inclination to behave pro-socially. That is, oxytocin seems to affect the degree of trust (from the investor to the trustee in this game), but not the degree of reciprocity (from the trustee to the investor), which is also in agreement with the evidence available for non-mammals. humans.
