Studies show that most smokers want to quit. So why are some people more successful at cutting out nicotine than others? The latest studies looking at the brains and behavior of smokers may provide some explanations.

Some people may be hardwired to have an easier time giving up their cigarettes, suggests one new trial described in the journal Neuropsychopharmacology. It turns out that some smokers start out with a particularly rich network of brain neurons in an area called the insula, which regulates cravings and urges and communicates cues: like seeing a cigarette or smelling tobacco smoke, then wanting to light up. Joseph McClernon, an associate professor of psychiatry and behavioral sciences at Duke University School of Medicine, ran MRI scans of 85 smokers who puffed more than 10 cigarettes a day. The smokers were then randomly assigned to continue smoking their brand or to smoke low-nicotine cigarettes, along with nicotine replacement therapy, for 30 days. All of the people in the study were then told to stop smoking and given nicotine replacement for 10 weeks.

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Those who relapsed during that time tended to have lower activity in the insula, particularly in the connections between the insula and other motor areas that translate cravings into action, while those who successfully kicked the habit showed more robust activity in this brain region. The pattern remained strong despite how many cigarettes the smokers smoked.

“We’ve known for a while that some people seem to be able to quit and other people can’t,” says McClernon. “This gives us a better sense of what neural mechanisms might underlie those differences.”

The results suggest that it might be possible to identify people who may have a harder time quitting—a quick MRI scan of their brains would reveal how much activity they have in their insula—and provide them with more support in their attempts to quit. “Some smokers might benefit from more intensive, longer duration or even different types of interventions to stop smoking,” says McClernon. “They might need a higher, different level of care to help them make it through.”

But how much this system can be manipulated to help smokers quit isn’t clear yet. Previous studies show how potentially complicated the insula’s connections may be—smoking patients who have strokes and damage to the insula suddenly lose their desire to smoke and quit almost cold turkey. McClernon believes that the richer connections may not only promote interactions between cravings and behavior, but also enhance the connections that can inhibit or suppress those urges as well. Having a more intense communication in the insula may help strengthen the ability to quiet urges and inhibit the desire to smoke, despite cues and the urge to light up.

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But even if you’re not blessed with a brain that’s wired to make quitting easy, you still have options. In another study, published in the New England Journal of Medicine, scientists studied one of the oldest and most reliable ways to motivate people: money. In that trial, Dr. Scott Halpern from the University of Pennsylvania and his colleagues assigned 2,538 employees of CVS Caremark to one of five different smoking cessation programs. All received free access to nicotine replacement and behavioral therapy, and some were also assigned to an individual reward program in which they could earn up to $800 if they remained abstinent at six months. Another group was assigned another individual deposit program which was similar, except they had to pay $150 to participate, which they got back if they remained abstinent. Others were assigned to group versions of the reward and deposit programs so that what they received depended on how many in their group quit successfully.

Not shockingly, more people who were assigned to the reward program (90%) agreed to participate than people who were assigned to the deposit strategy (14%), likely because most people weren’t wiling to put their own money on the line. But when Halpern looked more closely at those who did enroll, the smokers in the deposit programs were twice as likely to be abstinent at six months than those in the reward group and five times as likely to be smoke-free than those who received only free counseling and nicotine replacement.

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That’s not entirely surprising, says Halpern, since having some of their own money at risk provided more motivation for the smokers to quit. When it comes to incentivizing smoking cessation, “adding a bit of stick is better than having just a pure carrot,” he says.

Finding the perfect balance of stick and carrot, however, may be more challenging. Halpern believes that from the perspective of an employer, insurer or government, offering even higher rewards than the $800 in the study and lowering the deposit slightly might still provide benefits to all parties. Smokers cost an average of $4,000 to $6,000 more each year in health services than non-smokers, he says, so offering even as much as $5,000 can still result in cost savings for employers, many of whom are now dangling financial incentives in front of their smoking employees to motivate them to quit.

How the financial carrot is proffered is also important, says Halpern. Now, most employers or insurers reward quitting in more hidden ways, with bonuses in direct deposit accounts or with lower premiums. While helpful, these aren’t as tangible to people, and humans respond better to instant gratification. “They’re rewarding people in ways that are essentially blind to the way human psychology works,” he says. “The fact that the benefits occur in the future make them a whole lot less influential than if people were handed money more quickly. Our work suggests that in addition to thinking about the size of the incentive, it’s fundamentally important to think about how to deliver that money.”

Another factor that can make financial incentives more powerful is to make the experience more enjoyable, either by introducing some competition in a group setting or encouraging smokers along the way. In the study, smokers in the group programs were not any more successful than those in the individual regimes, but that may be because the employees didn’t know each other. Grouping colleagues in the same office might have more of an effect, says Halpern. Either way, he says, incorporating such incentives to help more people quit smoking is “really a win-win.”

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