A new study from the Kellogg School of Management concludes that most people have too much faith in their own ability to resist temptations such as drugs, sex, and greed.

Researcher Loran Nordgren and colleagues cite a “restraint bias” that causes people to overestimate their willpower and increases the risk of engaging in addictive or impulsive behavior. A series of experiments to gauge impulse control included testing the willpower of smokers to abstain after watching a movie about smoking.

“People are not good at anticipating the power of their urges, and those who are the most confident about their self-control are the most likely to give into temptation,” Nordgren said. “The key is simply to avoid any situations where vices and other weaknesses thrive and, most importantly, for individuals to keep a humble view of their willpower.”

“A system which assumes people will control themselves is going to fall prey to this restraint bias; we expose ourselves to more temptation than is wise, and subsequently we have millions of people suffering with obesity, addictions and other unhealthy lifestyles,” explainedNordgren. “And, while our study focused on personal behaviors like smoking and eating, it is easy to apply our findings to a broader context. Understanding the power of temptation, you might also ask about the extent to which we need oversight or regulatory guidelines for business and political leaders.”

The study will appear in an upcoming issue of the journal Psychological Science.