Why are bad habits so hard to break? 

Neuroscientist Carl Hart, PhD, journalist Charles Duhigg, and psychologist Adam Alter, PhD explain how your brain wires habits as cue-routine-reward loops that control nearly half of your daily life. They show why willpower alone rarely works, why technology fuels new forms of addiction, and why habits can only be replaced, not erased.

We created this video for Brain Briefs, a Big Think interview series created in partnership with Unlikely Collaborators. As a creative non-profit organization, they’re on a mission to help people challenge their perceptions and expand their thinking. Often, that growth can start with just a single unlikely question that makes you rethink your convictions and adjust your vantage point. Visit Perception Box to see more in this series.

So here's the thing to recognize about your bad habit. You cannot eradicate your bad habit. You have to trick your neurology.

We are living through this huge evolution in our understanding of habits, and it's being driven primarily by understanding the neurology of where habits come from.

I thought that drugs were the source of the problems that we were seeing in our community. Turns out not only was I wrong, society was wrong.

Basically, we tend to develop addictions when we have a psychological need. At those moments, smartphones tend to be great vehicles for providing the hits that you need when you need them.

I think that there is this interior sense when a bad habit strikes that people know that they have a bad habit. It just seems like a lot of people, even the most successful people, don't necessarily know where to start at changing it.

The ability to form habits is one of the most important and amazing evolutionary tactics that the human race has come up with—and all primates and almost all animals for that matter. When you form a habit, you can execute a fairly complex series of behaviors without having to think really hard about it. And what that means is that it lets us think about other things. But the downside of a habit is that you stop thinking while you're doing a habit. So as a result, you become less aware of the negative consequences of that behavior.

There is a woman named Wendy Wood who did a study when she was at Duke, and what she found was that about 45% of all the behaviors that someone did in a day was habit. It wasn't decision-making. And this gets to the way that habits work, which is that there's this thing called the habit loop. There's three parts to it: first, a cue, which is a trigger for behavior; then the behavior itself, which we usually refer to as a routine; and then the reward. The reward is actually why the habit happens in the first place—it's how your brain decides whether to remember this pattern for the future or not. The cue and the reward become neurologically intertwined until a sense of craving emerges that drives your behavior.

If you take this framework and apply it to the behaviors that you do—for instance, backing your car out of a driveway, or why you suddenly feel hungry when you see a donut box on the counter at work but you weren't hungry five minutes earlier—you can find these cues and rewards that explain the behaviors.

Between 1990 and 2000, that is deemed the decade of the brain. There was a lot of money going into studying brain illnesses and disease, and into learning about the brain. During that time, we were looking for some neural footprint of addiction. We thought that once cocaine interacted with dopamine neurons, it had this almost magical power over the person's behavior. We've learned that's not necessarily the case.

So when we think of drug addiction, it's important to keep the focus on the person's behavior: Are they not showing up for work? Are they not meeting obligations at home or school? All of these are important indicators of whether someone is drug-addicted or not—and notice, I didn't look at anyone's brain. I'm really looking at behavior.

Behavioral addiction is a lot like substance addiction in many ways. Basically what has to happen is that there's a behavior you enjoy doing in the short term that you do compulsively, so you keep returning to it over and over again, but in the long term it harms your wellbeing—and it can harm your wellbeing in lots of different respects. It's a much newer, more recent phenomenon.

The reason we've got these new forms of addiction comes down to two main things. First, technology is much more sophisticated and advanced than it was even 20 years ago. You're able to deliver the kinds of rewards that you need for a system to be addictive. What people are looking for is unpredictability and the rapid feedback of either rewards or, if negative, negative experiences—and you actually need that mix of positive and negative feedback. Just as when you post something online: sometimes you get a lot of hits, sometimes you don't, and it's that unpredictability that we find so compelling.

Whenever we're bored, lonely, unsure of what to do next, or don't feel like we're having an effect on the world, those are the moments when you're looking for what some people call the adult pacifier. Smartphones tend to be a great adult pacifier because at those moments, you turn on your screen, swipe, and feel relaxed again.

If you just try and say, "I'm gonna use willpower to make this behavior go away," it's not gonna work. Every scientist who's worked on habits will tell you: once the neurology of that habit is set, it's always there in some form or another. So instead of thinking about eradicating this bad habit or just using willpower to ignore it, you need to change it.

There's this thing known as the golden rule of habit change: if a habit is made up of a cue, a routine, and a reward, you can't change all three parts at once. You shouldn't even try. What you really want to change is the routine—the behavior. To do that, you keep the same cue and deliver the same reward, and you'll be able to shoehorn that new behavior into your daily pattern.

You can't change everything overnight. You can't suddenly say, “I want a brand new habit tomorrow,” and expect it to be easy and effortless. You have to give yourself permission to take a little time to practice because you're building up neural pathways associated with a certain behavior, and those pathways build up over time. You can't speed up that process any more than is natural.