SATURDAY, Aug. 28 (HealthDay News) -- While the hormone oxytocin makes people more trusting, it doesn't make them more gullible, a new study shows.

Oxytocin -- a naturally occurring hormone that functions as a neurotransmitter in the brain -- plays an important role in social behavior. Increased levels of the hormone have been linked with better maternal-infant bonding and greater overall caring, generosity and trust, but it hasn't been known whether this heightened trust was selective.

In this Belgian study, participants received either a placebo nasal spray or an oxytocin nasal spray, and were then asked to play a trust game in which they received a certain amount of money they could share with a partner. Any money they shared with the partner would then triple, but the catch was that the partner then got to decide what to do the money -- he or she could either keep it all or split the amount with the giver.

The participants were paired up with a computer and virtual partners, some of whom appeared to be reliable (the type to share the money) and some who appeared unreliable (those likely to keep it all for themselves).

Compared to participants who were given the placebo, those who received the oxytocin offered more money to the computer and the reliable partners. However, those in the oxytocin group were no more likely than those who received the placebo to share money with a seemingly unreliable partner.

The results show that oxytocin may make people more trusting, but only in certain situations.

In a news release from the Association for Psychological Science, lead researcher Moira Mikolajczak, a psychological scientist at the Catholic University of Louvain, concluded that "oxytocin is not the magical 'trust elixir' described in the news, on the Internet, or even by some influential researchers."

The study appears online Aug. 24 in the journal Psychological Science.

More information

To learn more about oxytocin, visit the http://www.apa.org/monitor/feb08/oxytocin.aspx.

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