Megan, like all parents, hates the whining and nagging: “It’s driving me crazy. My children whine and complain until they get what they want. I try not to give in, but sometimes it’s just impossible. What can I do?”

(That’s an excerpt from a much longer message. You get the idea.)

Let’s look at whining from a classic behavioral approach. Stay with me, here — behavioral theory is a big part of why we do the things we do, children and adults alike. It’s worth understanding.

What we’re talking about here is called “operant conditioning.” Basically, whether people continue to do something depends on the consequences. If complimenting your spouse gets you a friendly smile or peck on the cheek, you’ll keep doing it (assuming you like smiles and kisses.) If your child’s whining means she gets what she wants, she’ll keep doing that, too. A related term is “positive reinforcement” — that’s a reward or benefit that comes after a behavior. Positive reinforcements (giving a child exactly what she wants) make it more likely that the behavior (whining) will happen again.

So: Step one of dealing with whining (or many other undesirable behaviors) is to remove the positive reinforcement. But there’s a twist, here — it turns out that the schedule of the positive reinforcers can change how well it works. This might not be intuitive, but it turns out that regular, always-given, predictable positive reinforcements are not as lasting or powerful as irregular, unpredictable, changing positive reinforcers.

Think about vending machines and casinos. With a vending machine, you always get exactly what you ordered (assuming the stupid thing isn’t broken — there’s an interesting behavioral lesson about that situation, too, but we’ll save that for another time.) People who get things from vending machines are positively reinforced, but they don’t typically crave vending machines. And: when the positive reinforcement ends (say, for 1 or 2 times you don’t get your bag of Funyuns), you’ll quickly stop using the vending machine.

But at a casino, you don’t know what your reward will be, or even if you’ll get one. In fact, most of the time, you get nothing at all. But that kind of reinforcement, the “sometimes-surprise” schedule, reinforces the behavior even more effectively. Think about people pumping money into slot machines, only to get occasional, unpredictable rewards.

Let’s come back to whining. If you reinforce the whining sometimes, or in an unpredictable way (“Here! Just have the whole bag of lollopops!”), you’ll unintentionally be encouraging the behavior even more than if you always said “yes.” If Megan is serious about stopping the whining, she has to stop reinforcing it, and shouldn’t give in. Ever.

What about punishment to stop whining? A punishment is an action you take after the behavior, a consequence that’s designed to stop the behavior. It turns out that behavioral studies in animals, children, and adults show that punishment is typically only temporarily effective. Yelling at your child for whining, or restricting privileges, or some other punishment: none of these will work well. That’s like the vending machine giving you a bag of stale chips. You’ll be mad, and might avoid the vending machine for a few days, but you’ll be back. Or, imagine, if a casino sometimes just took your money away from you. That’s a valid punishment, but it doesn’t really change a behavior as well as completely stopping the positive reinforcements (in a casino, the occasional big payouts.) If the punishment of losing money at casinos actually worked, they’d all be out of business.

Sometimes, there’s more to whining than just behavior and consequences. I’d consider the child’s development and communication skills, and overall parenting style, expectations, mental health, resource scarcity — lots of things beyond behavioral theory. But a straight-up behavioral approach is sometimes the simplest, best way to get children to stop with the whining. And if it works, Megan owes me a trip to Vegas. Or at least a bag of Funyuns.

Roy Benaroch is a pediatrician who blogs at the Pediatric Insider. He is also the author of A Guide to Getting the Best Health Care for Your Child and the creator of The Great Courses’ Medical School for Everyone: Grand Rounds Cases.

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