Mistrusted men bring up hormonal issues

The predictable conclusion is that men are pigs who get off on lying.

By Dan Vergano, USA TODAY
Men, not women, react hormonally when they aren't trusted, a research team reports. And the team's experimental finding may explain why some men take negotiations over money more personal.

The experiment worked thusly: In a bid to understand how people react to being mistrusted, the team led by Paul Zak of the Center for Neuroeconomics Studies at the Claremont (Calif.) Graduate University asked 212 men and women to play the "trust game."

The trust game, long used in psychology experiments, gives one player some money, $10 in this case, and asks them to give any amount of it desired, including none, to a second player. The second player will receive triple that amount and will then get to decide how much they want to give to the first player, both players are told. The more the first player trusts the second player, who they never meet, the more money they will send over in the expectation that the second player will do the decent thing and kick back a fair return.

Zak's team added a blood test given to each player after they made their decision, to check their hormone levels.

In the experiment, just reported in the American Economic Review, the researchers found women were less trustful than men, sending over about a dollar less, on average, to the second player. If the first player sent over $5 or less, the researchers counted that as a signal of "distrust" for the second player.

The big surprise came in the blood test: measures of a testosterone marker in the blood tests found men's testosterone levels jumped by about a third when they were distrusted. Women on the other hand, didn't show any jump at at all. Men normally had at least five times more testosterone than women in the experiment, but the difference in reactions was clear, the researchers say.

"The relationship between testosterone and aggression is well established in animals, although more equivocal in humans," notes the study. But you don't have to believe in "testosterone poisoning" to think that women in general might make better business partners than men, Zak suggests. Women in the study tended to kick back more money to the first player when they were trusted.