"Trust" Hormone's Smell Helps Us Hand Over Cash, Study Says

Stefan Lovgren
for National Geographic News
June 1, 2005

When large sums of money are concerned, it is advisable to trust nobody, mystery writer Agatha Christie once said.

But what if there is a biological reason for why we would trust others with our cash?

Scientists have discovered that the hormone oxytocin, when sniffed, makes people more prone to trust others to look after their money.

To test the trusting effect of oxytocin, the researchers studied people who played an investment game. In the game, participants would choose how much money to hand over to a trustee. Investors were far more trusting after inhaling the hormone, researchers found.

"This is the first study that can describe the underlying biological mechanism of trust in humans," said Markus Heinrichs, a clinical psychologist at the University of Zurich in Switzerland. Heinrichs co-authored the study, which will appear tomorrow in the journal Nature.

The findings have important implications for the study of conditions in which trust is diminished (as in the mental disorder autism) or augmented. Ongoing research suggests that inhaling oxytocin may help reduce anxiety in people with social phobia, for example, and help them to interact better with others.

Animal Bonding

Almost all human interactions—from love and friendship to leadership and economic transactions—require an element of trust. Yet little is known about the biological underpinnings of the feeling.

"We know a lot about institutional factors that foster trust—information, repeated interaction, and so on—but nothing about why we trust when there is basically no objective reason to do so," said Michael Kosfeld, an economist at the University of Zurich. Kosfeld is a co-author of the study.

That oxytocin would promote trust is not entirely surprising. Humans release the hormone during everything from labor to sexual orgasm. But in many animals the molecule is also known to promote social interactions, including pair bonding.

"I've been doing research on oxytocin in humans for many years and found positive effects of [it] on stress and anxiety," said Heinrichs, the psychologist. "However, I was not sure to find oxytocin to influence such a complex behavior like trust."

In animals oxytocin may lower the natural resistance they have to the proximity of others, making them more likely to approach other animals. Approach behavior and trust are closely linked.

Continued on Next Page >>


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