Testosterone bumps up status-seeking behavior, not aggressive risk-taking
Do those with more testosterone coursing through their bodies make riskier, more aggressive decisions? Popular culture and even rodent studies seem to have borne out this trite truism about the sex hormone, but researchers in Switzerland and the U.K. tested whether this perception really held true for humans in a controlled environment—and arrived at counter-intuitive findings.
"We wanted to verify how the hormone affects social behavior," Christoph Eisenegger, a neuroscientist at the University of Zurich and lead author of a new paper on the subject, said in a prepared statement. "If one were to believe the common opinion, we would expect subjects who received testosterone to adopt aggressive, egocentric and risky strategies."
To test the idea, the research team gave 121 women either 0.5 milligrams of testosterone or a placebo and had them play an ultimatum bargaining game. With real money on the line, one player was in charge of proposing how the two would split the funds via a computer interface. The other player could reject an offer if she thought it unfair—and if the game ended in a stalemate, no money was distributed. Given the common wisdom about testosterone, the players who had gotten the testosterone boost should be more likely to take a riskier, antisocial approach and lowball the initial offer in an effort to keep more money for themselves.
The behavior of the test subjects, however, did not ultimately confirm the stereotypes, according to the results, published online Tuesday in Nature (Scientific American is part of Nature Publishing Group).
Those who had received testosterone actually made "significantly higher offers" than those who had gotten the placebo (offering an average of 39 percent of the money and 34 percent, respectively)—even after controlling for baseline testosterone levels and perceived testosterone consumption, the paper authors noted. These testosterone-fueled offers worked, "thereby reducing bargaining conflicts and increasing the efficiency of social interactions," the researchers wrote.
They attributed this shift to a desire of the testosterone group to maintain their images—by avoiding rejection—aligning with the so-called social status hypothesis.
But might the different bargaining approach be based on an increase in altruism? The authors refute this explanation, noting that if this were the case they would have seen more offers accepted under the influence of testosterone (which they didn't, finding, in fact no significant change in the ways the receivers responded to the offers when compared with a similar test of 180 women who had received no testosterone).
This study isn't the first to cut away at some of the myths about testosterone. Previous research has found that although the hormone is often prevalent in violent individuals—both male and female—it alone doesn't lead to violence.
Does this mean testosterone has no role in complicating such social negotiations? It is likely more complex than that, Michael Naef, an economist at Royal Holloway, University of London and co-author of the study, noted in a prepared statement. Indeed, the cultural concept of testosterone itself might be to blame for some antisocial and aggressive behavior. The researchers found that of those who strongly believed they had gotten the testosterone pill—whether or not they had it or the placebo—actually "behaved much more unfairly," the authors wrote.
And: "In a society where qualities and manners of behavior are increasingly traced to biological causes and thereby partly legitimated, this should make us sit up and take notice," Naef said.
Publicada por Sérgio RSV em 08:25 0 comentários
Does Testosterone Have a Bad Rap?
By Constance Holden
ScienceNOW Daily News
8 December 2009
Testosterone has a reputation for causing violent and antisocial behavior. But that's a bad rap, according to a new study. Women given the hormone acted more fairly in an economic game than did those given a placebo. Interestingly, however, women in the placebo group were more antisocial if they thought they had received testosterone, indicating that our negative attitudes toward the hormone have a powerful sway on behavior.
Scientists led by Ernst Fehr, a professor of neuroeconomics at the University of Zurich in Switzerland, suspected that testosterone is really about gaining and maintaining social status. And although status concerns lead to aggression, they theorized that testosterone does not necessarily make a person more self-seeking.
The team tested this idea by recruiting 121 women in their 20s to play a game that tests fairness. Two players, A and B, have to agree on the division of 10 money units, in this case Swiss francs. A proposes a division; B can only accept or reject. If B rejects the offer, neither gets any money. All the women were given a dose of either testosterone or a placebo under the tongue. Then 60 women designated as A played the game three times with three different partners, communicating through a computer.
A "fair" offer would be a 50-50 split. So, according to common wisdom, A would make more unfair offers if she were high on testosterone. The status hypothesis predicts the opposite: An unfair offer is more likely to evoke a rejection, which is an affront to A's status. So A is more likely to make an offer that B will accept.
The status hypothesis won. The women given the testosterone made significantly higher offers on average, the group reports online today in Nature: 3.9 francs versus 3.4 francs for the placebo group. "Our interpretation of this finding is that testosterone renders concerns for social status more prominent," says Fehr.
But the results changed depending on what the women believed they had received. Based on questionnaires, the researchers divided the volunteers into women who thought they had received testosterone and those who thought they had received placebo. Those who got the hormone but thought they got a placebo were the most fair; in more than 60% of their offers, they proposed a 50-50 split of the francs. Women who got the placebo but thought they got testosterone were the most unfair; in only 10% of the offers did they propose an even split of the money. That indicates, says Fehr, that the subjects' negative assumptions about testosterone--not the hormone itself--led to antisocial behavior.
Fehr says the group used women because the pharmacokinetics of testosterone doses in women are well-understood. He hopes to do the same experiment with men.
The research should help "demystify the wrong ideas about ... the 'antisocial' hormone testosterone," says Jack van Honk, a neuroscientist at Utrecht University in the Netherlands. But economist Niklas Zethraeus of the Stockholm School of Economics isn't convinced that testosterone influences fairness one way or the other. His group published a study this year using a larger sample that found no connection between sex hormone levels and economic behavior.