The hormone testosterone has already been linked to promoting aggressive and risky behavior, but now it may have another side effect: that of truth serum.
In a study of more than 90 men, scientists from the University of Bonn, Germany, found that subjects treated with a dose of testosterone before the study told fewer lies than those who received a placebo.
"Testosterone has always been said to promote aggressive and risky behavior and posturing," says researcher and neuroscientist Bernard Weber. However, more recent studies indicate that it also fosters social behavior. Prior research has suggested that the hormone may actually cause people to be more "prosocial" in that they voluntarily act in the interest of others, writes the Atlantic magazine, but exactly how the hormone influences behaviors isn't understood.
For this latest study, 46 subjects were treated with testosterone by applying it to the skin in gel form, while 45 subjects received a placebo. The next day, the subjects played a dice game in which it was easy for the men to lie to earn more money, with no possibility of being caught. The study was designed so that it was impossible even for the researchers to detect whether a subject was lying or not. Rather, they used statistics to analyze reported earnings that were higher than probability would allow, inferring from these how honest the subjects were being.
While many people in the study lied about the game, there was a noticeable difference between the men boosted with testosterone and those who weren't -- the testosterone group avoided the temptation to cheat more often. Blood tests confirmed the results that high testosterone levels were linked with more honest game playing.
"Test subjects with the higher testosterone levels had clearly lied less frequently than untreated test subjects," says co-author Armin Falk. "This result clearly contradicts the one-dimensional approach that testosterone results in anti-social behavior."
The study was published last week in the journal PLoS One.