Oxytocin, 'love hormone,' promotes group lying, according to researchers

The research was published this week in the Proceedings of the National Academy of Science (PNAS).

"Our results suggest people are willing to bend ethical rules to help the people close to us, like our team or family," says Dr. Shaul Shalvi of Ben-Gurion University of the Negev's Department of Psychology and director of BGU's Center for Decision Making and Economic Psychology. "This raises an interesting, although perhaps more philosophical, question: Are all lies immoral?"

Dr. Shalvi's research focuses on ethical decision-making and the justifications people use to do wrong and still feel moral. Specifically, he looks at what determines how much people lie and which settings increase people's honesty. Very little is known about the biological foundations of immoral behavior.

"Together, these findings fit a functional perspective on morality revealing dishonesty to be plastic and rooted in evolved neurobiological circuitries, and align with work showing that oxytocin shifts the decision-maker's focus from self to group interests," Shalvi says.

"The results highlight the role of bonding and cooperation in shaping dishonesty, providing insight into when and why collaboration turns into corruption."

Oxytocin is a peptide of nine amino acids produced in the brain's hypothalamus, functioning as both a hormone and neurotransmitter. Research has shown that in addition to its bonding effect in couples and between mothers and babies, it also stimulates one's social approach.

Higher levels of oxytocin correlate with greater empathy, lower social anxiety and more pro-social choice in anonymous games; reduction in fear response; and greater trust in interpersonal exchange. It also stimulates defense-related aggression.

In the experiment designed by Shalvi and fellow researcher Carsten K. W. De Dreu of the University of Amsterdam's Department of Psychology, 60 male participants received an intranasal dose of either oxytocin or placebo. They were then split into teams of three and asked to predict the results of 10 coin tosses.

Participants were asked to toss the coin, see the outcome and report whether their prediction was correct. They knew that for each correct prediction, they could lie and earn more money to split between their group members, who were engaging in the same task.

"The statistical probability of someone correctly guessing the results of nine or 10 coin tosses is about one percent," says Shalvi. "Yet, 53 percent of those who were given oxytocin claimed to have correctly predicted that many coin tosses, which is extremely unlikely."

Only 23 percent of the participants who received the placebo reported the same results, reflecting a high likelihood that they were also lying, but to a lesser extent compared to those receiving oxytocin.