A study by researchers from California Institute of Technology (CalTech), the Wharton School, Western University and ZRT Laboratory found that higher levels of testosterone make men more impulsive. The team tested the hypothesis that, the more this hormone is present in males, the more they rely on their intuitive judgments and lessen cognitive reflection.

Cognitive reflection is a decision-making process by which a person takes a step back and checks whether their gut reaction to something makes sense. The California Institute of Technology (CalTech) researchers discovered that men given doses of testosterone did not do well on a test designed to measure cognitive reflection than to the group given a placebo. The study will be published in an upcoming issue of the journal "Psychological Science."

In a press release on CalTech's official website, Colin Camerer, the Robert Kirby Professor of Behavioral Economics and T&C Chen Center for Social and Decision Neuroscience Leadership Chair, revealed that the testosterone group was faster in making snap judgments on brain teasers where one's initial guess is usually wrong. He noted that the hormone is either inhibiting the process of mentally checking the answer or increasing the intuitive feeling that they are right.

This is one of the largest studies of its type ever conducted. 243 males were randomly selected to receive a dose of testosterone gel or placebo gel before they were asked to take a cognitive reflection test. They were also given a math task to control for participant engagement, motivation level and basic math skills.

Participants were not given a time limit on answering the questions. They were also offered $1 for each correct answer and an additional $2 if they were able to answer all questions correctly.

The results showed that the testosterone group got significantly lower scores than the men who received the placebo. They answered 20 percent fewer questions correctly on average.

The group given a dose of testosterone also gave incorrect answers more quickly and correct answers more slowly compared to the placebo group. The results demonstrated the clear causal effect of testosterone on human cognition and decision-making.