Oxytocin Increases Trust in Humans

This landmark study, published in Nature in 2005, investigated for the first time the causal role of oxytocin in human trust behavior. The researchers used an economic trust game paradigm in which 128 healthy male participants received intranasal oxytocin (24 IU) or placebo before making financial decisions involving interpersonal trust.

The results were remarkable: participants who received oxytocin transferred significantly more money to the partner in the trust game, demonstrating a substantial increase in willingness to trust. Interestingly, oxytocin did not increase the general willingness to take risks, as demonstrated by a control game without a social component, suggesting that the effect is specific to social interactions.

The study carefully controlled variables such as mood and calmness of the participants, which did not differ between groups. The proposed mechanism involves the reduction of aversion to social betrayal, allowing individuals to overcome psychological barriers to trust.

This research was fundamental in establishing oxytocin as a modulator of human social behavior and opened an entire field of investigation into the effects of oxytocin on social cognition, with implications for conditions such as autism and social phobia.