Got caught cheating? Blame it on hormones. Testosterone gives us the courage to cheat, and cortisol motivates us to follow through, according to a new study from researchers at Harvard and the University of Texas.

We’ve known hormones affect behavior since the 19th century, but this study suggests how much they affect our actions. The research shows that hormones actually play two roles when it comes to cheating (and being unethical in general): A person with higher levels is more likely to cheat, and a subsequent drop in those levels after the act makes cheaters feel good, reinforcing that behavior.

To study this, the researchers had 117 participants do a math test: The more answers they got right, the more money they’d earn. Participants were asked to grade their own tests, then report their scores.

Testing the participants’ saliva before and after the test, researchers found that people with higher testosterone and cortisol before the test were more likely to lie about how many they got right. Higher testosterone is linked to decreased fear of punishment and heightened reward sensitivity, and higher cortisol is linked to chronic stress. After the test, cheaters had lower levels of these hormones —essentially indicating stress relief: Lower cortisol meant lower stress, which, to the brain, is pretty rewarding.

These post-cheating good vibes reinforce bad behavior, said psychologist Robert Josephs, the corresponding author on the study, in a press release.

Can we use these findings to help deal with the cheating scandals sweeping colleges across the United States? Finding a way to lower testosterone and cortisol levels in students might be a good start. Cortisol levels, for example, drop with stress-relieving activities like yoga, meditation, and exercise. Testosterone’s a bit harder to deal with, but studies have shown that group assessments — rather than individual ones — eliminate its effects on behavior.

Photos via Flickr