GIVEN how hazardous it is to their health, why do smokers continue to smoke?

It’s not that they are all hopeless addicts. Many smokers are capable of quitting.

It’s not that they are ignorant. Studies show that smokers are at least as informed as nonsmokers about the risks of smoking — and possibly more informed.

You might suspect, then, that smokers tend to be risk takers by nature. And some evidence suggests that smokers do take more risks than nonsmokers: they are more often involved in traffic accidents, less likely to wear seat belts and more likely to engage in risky sexual behavior. Women who smoke even have mammograms less frequently than their nonsmoking counterparts.

But we don’t believe that smokers have a greater tolerance for risk. As we argue in a study published this month in the journal PLoS One, the personality trait that distinguishes smokers from nonsmokers is their relative inability to delay satisfaction and respect long-term considerations (like their health). In other words: it’s their poor self-control.