Generosity Hormone

"We said, 'If you gave money, how much would you give.?' And, "If you received it and you have a chance to reject how much you were given because it was just too stingy, how much would you accept? What's the smallest amount you would accept?'"

He wrote in the journal PLoS One that subjects who got a snort of oxytocin gave 80-percent more money than those who inhaled just a saline solution.

"That's substantial-- that's actually real money that you could go and buy lunch with, but indeed you gave to a stranger," says Zak, pointing out that he conducted the experiments at UCLA.

"We do these at UCLA because there's great heterogeneity in the subject pool. There's a large student population and they vary by major, by ethnicity; we don't recruit from a class so there's a great cross-section of individuals," he says.

He says the effect extended all across this cross-section. "Subjects who were generous in this experiment walked out of the lab with less money. And yet they did report they were less unhappy," says Zak. "They were equally as happy as people who walked out of the lab with more money. So generosity occurs because we're a social species and we care about the welfare of other people, in this case even complete strangers."

Empathy Versus Altruism

"The only reason this works is because we've asked you to take the other person's perspective. So we had this control task in which we didn't ask you to take the other person's perspective, and oxytocin had no effect," Zak says. "We do have some baseline altruism, so we found that a bit of the generosity was predicted by altruism, but empathy was quantitatively twice as important as baseline altruism.

"So it's really empathy and not altruism that seems to drive charitable giving," he says. "Now we understand why people actually give money to the Salvation Army when they leave their local store at Christmastime, why they give money to hurricane victims. We do that because we feel for them, we feel empathy for them.

In his controlled experiments, Zak deliberately removed any natural stimulators of oxytocin and empathy, and used artificial oxytocin to "push on the empathy lever" of some participants.

But he points out that there are many natural ways to boost our oxytocin levels-- including giving itself.

"We're being generous with others and we're releasing oxytocin in ourselves and in other people and we get great enjoyment from that," he says. He adds that it's well-known that hugging and cuddling also release the hormone but says so does sharing a meal with others.

"The rituals of the holidays, which often include many meals, is an important part of the bonding that we have between those friends and family that join us," he says.

Interestingly, Zak found that oxytocin had no effect on two percent of the participants and that these students fit the personality profile of sociopaths.

"If we infuse oxytocin into their brains, it has no effect on their behavior, so they're not generous at all," Zak says, claiming, "That's a good thing. It tells us there are individuals out there who are not people we want to interact with and we should be careful when we're having to trust another person and we should direct our generosity towards those who really need it."