When a mother in Ohio faked her address in order to send her child to a better public school, she got arrested. At trial she testified that she willingly lied to improve her child’s chances in life. She got jail time.

And not everyone was happy about that. The idea of bending moral codes to help a child seems forgivable, especially when a little lie might make a real difference in the rest of that child’s life. Are we quick to forgive—and quick to lie—because taking care of loved ones is what all mammals do?

Oxytocin is a brain chemical that helps human mammals feel more caring. Nursing mothers, for example, have huge levels of it in their blood. But men have oxytocin, too. It’s known widely as the “bonding hormone.” Research psychologists in Israel have reported on an experiment that looked at whether boosting people’s oxytocin levels made them more likely to lie for the benefit of people they liked.

The experimenters worked with sixty healthy men who volunteered to spray their nostrils with either oxytocin or placebo. (They weren’t told which substance they were spraying.) Then the experimenters assigned each man to a group of three. After the oxytocin had enough time to take effect and the men had had enough time to get to know each other, a computer played a betting game with each man individually. The men had to guess the outcome of an electronic heads-or-tails, coin-toss game. Each man was told that if he performed well, the friends he’d just made would get prizes. Each man was asked to keep score, and each man was alone when he keyed in his score to the computer. And because each man was alone he had the opportunity to lie. What none of the men knew, of course, was that the computer was also keeping score.

As expected, the men who had sprayed oxytocin into their nostrils lied more.  

Later, the psychologists re-ran the experiment to see whether oxytocin would increase lying when the men were told that only they would benefit from the coin toss game. When they weren’t trying to win prizes for their new friends, even the men who sprayed their nostrils with oxytocin didn’t lie more often. This suggests that oxytocin was responsible only for the feelings of friendship among men, and that those feelings were what prompted the men to lie. It is a “love-and-like” hormone, and not (the researchers were careful to point out) a dishonesty drug.

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Shaul Shalvia and Carsten K. W. De Dreub,”Oxytocin promotes group-serving dishonesty,” Proceedings of the National Academy of Sciences.

Photo credit Katie Tegtmeyer http://www.flickr.com/photos/katietegtmeyer/