Sex hormone connected with greater reliance on gut instincts and less self–reflection.
A study conducted by researchers from Caltech, the Wharton School, Western University, and ZRT Laboratory tested the hypothesis that higher levels of testosterone increase the tendency in men to rely on their intuitive judgments and reduce cognitive reflection – a decision–making process by which a person stops to consider whether their gut reaction to something makes sense. The researchers found that men given doses of testosterone performed more poorly on a test designed to measure cognitive reflection than a group given a placebo.

The research appeared in the journal Psychological Science.

"What we found was the testosterone group was quicker to make snap judgments on brain teasers where your initial guess is usually wrong," says Caltech's Colin Camerer, the Robert Kirby Professor of Behavioral Economics and T&C Chen Center for Social and Decision Neuroscience Leadership Chair. "The testosterone is either inhibiting the process of mentally checking your work or increasing the intuitive feeling that 'I'm definitely right.'"

The study, which is one of the largest of its type ever conducted, included 243 males who were randomly selected to receive a dose of testosterone gel or placebo gel before taking a cognitive reflection test. A math task was also given to control for participant engagement, motivation level, and basic math skills.

The results show that the group that received testosterone scored significantly lower than the group that received the placebo, on average answering 20 percent fewer questions correctly. The testosterone group also "gave incorrect answers more quickly, and correct answers more slowly than the placebo group," the authors write. The same effect was not seen in the results of the basic math tests administered to both groups. The results "demonstrate a clear and robust causal effect of testosterone on human cognition and decision–making," they conclude.

The researchers believe that the phenomenon they've observed can be linked to testosterone's effect of increasing confidence in humans. Testosterone is thought to generally enhance the male drive for social status, and recent studies have shown that confidence enhances status.

"We think it works through confidence enhancement. If you're more confident, you'll feel like you're right and will not have enough self–doubt to correct mistakes," Camerer says.

Camerer says the results of the study raise questions about potential negative effects of the growing testosterone–replacement therapy industry, which is primarily aimed at reversing the decline in sex drive many middle–aged men experience.

"If men want more testosterone to increase sex drive, are there other effects? Do these men become too mentally bold and thinking they know things they don't?"

The paper is titled "Single dose testosterone administration impairs cognitive reflection in men." Co–authors are Camerer's former graduate student Gideon Nave (PhD '16), now at the Wharton School of the University of Pennsylvania; Amos Nadler of Western University in Canada; and David Zava of ZRT Laboratory.