Oxytocin and the Bottom Line

 
The Game

Paul Zak designed the “trust game,” which is based on the work of John Dickhaut and Kevin McCabe. The game always involves 2 people, the “subject” and the “stranger”—a person the subject has never met. It also involves money.

In Zak’s version, the subject is said to trust the stranger if the subject withdraws money from a fictional (or actual) account and then gives some of it to the stranger. The subject has been informed that on receipt of the funds, the stranger will reciprocate, returning either the same amount or an even greater amount of money, at a later date.

The trust game is divided into several steps, as described below (Figure). Because reactions to other people can be easily influenced by physical appearance, perceived affect, and even clothing, it is important that neither participant has face-to-face contact. Both the subject and the stranger are thus seated at computers away from each other. They are both given $10 for participating in the study.

Step A. The experiment begins when the subject is told by the computer to make a monetary decision. The subject is asked whether he or she would like to send all or a portion of his $10 to the stranger. The computer tells the subject that if he decides to part with some of the money, the stranger’s account will receive triple the amount that the subject donated. If the subject chooses to send $5, the stranger’s account will be credited with $15, plus the $10 the stranger already has. This is a pretty good deal for the stranger, who now has $25!

Step B. The computer now informs the stranger about the subject’s decision, and then asks the stranger, “Would you like to return some of the subject’s money?” The stranger is informed that he does not have to return any of the money. Even if the stranger decides to be generous, the “tripling” effect will not occur in the subject’s account. All decisions will remain confidential, no deception is ever allowed, and real money is at stake.

How do people react? The game has been performed numerous times in many countries, sometimes with breathtaking amounts of real money. Results from Zak’s laboratory are typical. About 85% of subjects give at least some money to the stranger. The stranger who receives the money almost always gives some of it back to the subject (about 98% return money).

Although the behavioral work is interesting, the really compelling findings concerned the levels of oxytocin in the participants’ brains, the results of which eventually led to an “intervention” experiment. The researchers found that the strangers’ brains produced bucketloads of oxytocin when they received their free monetary gift from the subjects. The interpretation was that they were “trusted.”

The effect was dose-dependent. The more money the strangers received, the more oxytocin was released in their brains. There was no increase in the level of this peptide in control groups who received monetary gifts in a random, nonpartner-dependent fashion.

Interestingly, strangers with higher baseline levels of oxytocin before the experiment almost always gave more money back to the subject as the experiment unfolded than did strangers with lower levels. That was not true of the subjects. Elevated levels of oxytocin in these participants did not predict higher initial monetary “gifting.” Clearly, there was a relationship between trusting behaviors and oxytocin levels. It was almost as if the establishment of trust-competent situations had to be inaugurated to coax oxytocin levels to come out of their neurological dens.