Your sleep habits aren’t the best, especially as the weekend comes to a close and the Sunday scaries set in. It seems so simple: go to bed at an earlier time to build better sleep habits. Yet there are some aspects of your environment—like your roommate washing dishes late at night, inconsistencies in your routine, and a lack of reward when you do get to sleep on time—that seem to get in the way. To change this, you might consider applying the cue-action-reward (CAR) model. 

The CAR model, also known as the habit loop, breaks down habits into three distinct parts: cue, action (routine), and reward. According to its creator, Charles Duhigg, the habit loop shows us how and why habits form.¹ Drawing from behavioral theories from psychology and neuroscience, Duhigg was the first to introduce the habit loop in his 2012 book, The Power of Habit.² Whether you’re looking to break a bad habit or hoping to form a good one, the CAR model might be the tool for you. The more that someone engages in the habit loop, the more ingrained a habit becomes.³ Let’s take a closer look at the three parts of the CAR model and consider a fourth component that serves as a natural expansion of the original framework.

The Cue 

Sometimes labeled as a reminder, the cue acts as a trigger, initiating the habit loop by signaling when and where a specific behavior should occur. You can probably think of many cues that relate to your poor sleep habits—your own internal thoughts but also external factors like the temperature of your bedroom, the noisiness of your roommates, or the softness of your pillow. A handful of common cue categories may include, but are not limited to:

1. Time
2. Place
3. Emotions
4. Others around you
5. Your most recent action 

For instance, the sound of your alarm clock in the morning: is it a favorite song, birds chirping, a tolerable default alarm noise, or something else? That noise is what you associate with waking up, signaling that it's time to get ready for work, which elicits certain feelings. Perhaps your weekend alarm is a different sound—or no sound at all, so it has a different association from your weekday wake-ups. 

The Action 

Often referred to as routine, the action is the behavior performed in response to the cue. The action forms the core of the habit loop. These actions are often unconscious, like checking your text messages first thing in the morning after turning off the alarm on your phone. Whether a habit is conscious versus unconscious makes a difference, especially when it's time to use the habit loop to make a change. While your reaction to your alarm clock is rather unconscious, where you choose to get your morning coffee may be more deliberate depending on how you’re feeling. 

The Reward 

The reward provides positive feedback, reinforcing the behavior and increasing the likelihood of repetition in the future. Rewards are effective at cementing habits so that they actually stick. For each of us, the types of rewards that are most beneficial may be highly subjective. No matter what reward works best for you, we shouldn’t underestimate our brain’s ability to form associations between cues, actions, and rewards—which combine to form the habit loop. It is key to be aware that some “rewards” can be detrimental. When it comes to bad sleep, there may likely be a trend of “bad” rewards keeping you up at night, such as scrolling for hours, promising yourself you’ll watch just one more TikTok. 

Adding Another C onto CAR: the Craving

In addition to the original three components of the CAR model, a fourth step may be considered: the craving.⁴ This would be the second step in the loop, representing the motives behind all of your habits. In the absence of motivation, it is unlikely that the proceeding step of an action will occur. Cravings may be understood as a wish to change internal feelings that arise due to a cue. For example, you crave the sugar rush you get from eating a Kit Kat. Of course, we don’t all have the same cravings—nor are we all tempted by the same cues. Not everyone has a sweet tooth like you, but someone else may have just as strong of a desire for a nice crunchy pickle. 

The Habit Loop and its Phases

A habit forms when an action feels sufficient at all four stages. Without a cue, there is no habit, or if a craving is weak, there won’t be enough motivation. With the addition of the latest element of the habit loop, cravings, let’s take a closer look at the loop in action.

The depiction of the cue-action-reward model as circular makes it easy to understand each stage of the loop. It goes as follows: a cue causes a craving, which motivates an action or behavior, which grants a reward that fulfills a craving, eventually forming an association with the cue.4 The habit loop can be seen as a neurological feedback loop that results in habitual behaviors when these steps are combined and repeated. 

We can divide the four steps into two larger categories known as the problem phase and the solution phase. The former captures the cue and craving, which create a desire to act, whereas the latter explains how the response and reward reinforce or modify the habit. Let’s dive into our Kit Kat example to sort out how the problem and solution phases appear in real situations:

Forming Good Habits and Breaking Bad Ones 

Whether it's about making new constructive habits or trying to eliminate old harmful ones, there is a framework we can apply to our behavior. The Four Laws of Behavior Change provide rules for addressing both good and bad habits, each influencing the actions you decide to take.⁴ When these laws are set up in a way that works for an individual, making good habits becomes easy—but if they aren’t in alignment with your goals, good habits feel unreachable. 

Let’s look at these laws for creating good habits first:⁴

In contrast, the laws can be inverted for breaking bad habits:⁴

Cue (Trigger): A signal that initiates a behavior, often tied to environmental or internal factors. Trigger is an alternative term that emphasizes its role in activating a specific habit. Seeing your clock strike 10:00 PM is a cue that signals that it’s time to start your bedtime routine.

Action: The behavior or response performed after encountering the cue, forming the core of the habit. You dim the lights, brush your teeth, and read a book to prepare for sleep.

Reward: A positive outcome or feedback received after the action, reinforcing the behavior. This may be the feeling of being refreshed and energized the next morning, which reinforces the habit of going to bed earlier.

Craving: The desire or motivation to achieve the reward, driving the individual to act on the cue. For instance, the feeling of sleepiness may indicate a craving for rest—prompting you to get ready for bed.

Four Laws of Behavior Change:  A model from James Clear that advocates for making good habits obvious, attractive, easy, and satisfying to reinforce them effectively and using the opposite principles for breaking negative habits.4 For instance, if someone wants to start exercising, they might place their workout clothes in plain sight (obvious), pair exercise with an enjoyable podcast (attractive), start with just five minutes of movement (easy) and track progress with a rewarding streak system (satisfying).

Reinforcement: The process by which rewards strengthen the association between the cue and the action. That feeling of waking up refreshed and energized the next morning reinforces the habit of going to bed early, making it more likely you'll repeat the behavior.

Behaviorism: A psychological theory focused on observable behaviors, which explains habits as learned responses to environmental cues through reinforcement. In relation to the habit loop, it emphasizes how rewards strengthen the connection between a cue and an action, making the behavior more automatic over time.

Habit Replacement Loop (HRL):  A framework that involves substituting an undesired habit with a more positive one by keeping the same cue and reward while changing the routine. For example, instead of reaching for a cigarette when stressed (cue), someone might practice deep breathing (new routine) while still achieving a sense of relaxation (reward).

The need to change habits is not a new phenomenon. The cue-action-reward (CAR) model is rooted in the study of human behavior, tracing back to Aristotle, who emphasized the role of repeated actions in forming habits.⁵ Later, in the 19th century, William James built on these ideas, highlighting the importance of cues and rewards in shaping automatic behaviors, laying the groundwork for modern habit psychology.

In the mid-20th century, behaviorism was the predominant school of thought in psychology, with the work of Ivan Pavlov and B.F. Skinner being particularly influential.⁶ Pavlov's experiments with classical conditioning demonstrated how environmental cues could trigger automatic responses, forming the basis of learned behaviors. Skinner expanded on this with operant conditioning, showing that rewards and reinforcements strengthen the association between actions and their outcomes. Together, their work highlighted the significance of cues, actions, and rewards in shaping behavior, providing the foundation for the CAR model and its role in understanding habit formation and behavior modification.

The cognitive revolution that followed reframed the CAR model by focusing on the role of mental processes in shaping behavior. Rather than viewing habits as purely reactive, researchers began to explore how thoughts, perceptions, and motivations mediate the link between cues, actions, and rewards.⁷ This shift highlighted the importance of decision-making, memory, and expectations in habit formation. By integrating these cognitive elements, figures like Albert Bandura advanced a more nuanced understanding of the forces driving behavior.

Books like Charles Duhigg's The Power of Habit (2012) and James Clear's Atomic Habits (2018) brought the Cue-Action-Reward Model into mainstream awareness.^{3, 4} Duhigg highlights the "habit loop” as the first formalization of the CAR model consisting of a cue triggering an action, which is reinforced by a reward, emphasizing the power of identifying and altering these loops to create change. Clear builds on this framework, focusing on practical strategies to design better habits by making cues obvious, actions easy, and rewards satisfying. Both authors underscore the importance of understanding the psychological mechanics of the CAR model to break bad habits and build lasting, positive routines.

The future of the CAR model lies in its integration with emerging technologies and behavioral insights. Advancements in AI and wearable devices could provide personalized cues and real-time feedback, tailoring habit loops to individual needs. Combined with insights from neuroscience, the CAR model may deepen our understanding of habit formation at the neural level, unlocking new therapeutic approaches. As behavioral science evolves, the CAR model’s adaptability ensures its relevance in addressing numerous challenges from altering health behaviors to organizational change.

Aristotle

A Greek philosopher who highlighted how repeated actions shape behavior and character. His ideas on habituation resonate with the cue-action-reward (CAR) model, influencing modern habit formation theories.

William James

A pioneering American psychologist who explored the role of habits in shaping human behavior, emphasizing their importance in daily life. His research laid the groundwork for the cue-action-reward (CAR) model, highlighting how repeated behaviors reinforce automatic responses.

B.F. Skinner

An American psychologist known for his work in operant conditioning, Skinner's research on reinforcement and behavior laid the foundation for understanding the reward component of habits.

Albert Bandura

A Canadian psychologist and key figure in cognitive psychology who is known for introducing the concept of observational learning and self-regulation. His research deepened the foundation of the CAR model by showing how cognitive factors, like self-efficacy and reinforcement, influence the habit loop.

Charles Duhigg

In The Power of Habit, Duhigg popularized the Cue-Action-Reward (CAR) model, explaining its role in habit formation and behavior change. He demonstrated how understanding this loop can help individuals and organizations identify and reshape habits to achieve desired outcomes.

James Clear 

In Atomic Habits, Clear expanded on the model by emphasizing the importance of small, incremental habit changes within the cue-action-reward framework. Clear introduced strategies, such as habit stacking and environment design, to make lasting behavior change more accessible and sustainable.

The cue-action-reward model is not limited to only personal habits—its broader influence is seen in fields like marketing, consumer behavior, and behavioral science. Let’s look into how the CAR model affects personal habits, but also influences fields that examine the behavior of larger social groups and societies. 

Habit Formation in Personal Development

The model provides a framework for building positive habits and breaking negative ones, empowering individuals to achieve long-term goals. Returning to our bad sleep anecdote, the solution seems simple—just sleep earlier, but environmental cues like your roommate’s late-night cleaning and your friend sending you TikToks disrupt the cycle. These cues trigger your existing habit loop, where the action (staying up) and reward (extra leisure time) keep you stuck in the same pattern.

To form better habits, the cue-action-reward (CAR) model can help you identify and adjust the cycle. For example, you could replace disruptive cues with calming ones, like dim lighting and a consistent wind-down routine, and reward yourself for sticking to your bedtime with small incentives, like a favorite podcast or cup of tea. The CAR model can be used more generally for understanding and reshaping habits, making it applicable to improving various personal routines, from exercise and eating habits to productivity and stress management.

Influence on Marketing and Consumer Behavior

Businesses leverage the CAR model to design products, advertisements, and loyalty programs that drive customer engagement and retention. Aside from the iconic “Wrapped” (which does have insights from behavioral science baked into it) that we eagerly await at the end of the year, we all know about Spotify's "Discover Weekly" playlist.⁸ With the habit loop in mind, Spotify identified the user’s craving: the desire to find new music. They followed this with the action of listening to a curated playlist and concluded with the reward of discovering songs users enjoy, fostering satisfaction and loyalty.

An app like Spotify is only one example of where the CAR model can improve user retention, just as other companies get customers to buy a product, become returning customers, or use their service in copious amounts by looping them into recurring habits. By leveraging the cue-action-reward (CAR) model, marketers can design products and experiences that tap into natural habit loops, creating long-term engagement and a stronger connection with their audience.

Applications in Behavioral Change Interventions

The CAR model is central to interventions in health, education, and workplace settings, helping to promote sustainable behavior changes and improve outcomes. Under the umbrella of health, habits—especially those we wish to change—are often closely linked to mental health patterns. Let’s zoom in on an example of the habit loop’s application to therapeutic approaches like cognitive behavioral therapy (CBT), an intervention that integrates approaches like identifying negative thought patterns and their corresponding actions in order to make a change.

For those seeking help via CBT, a version of the CAR model called habit replacement looping (HRL) may be a suitable solution for tackling specific habits like thumb-sucking, nail-biting, or even stress responses from PTSD.⁹ According to Duhigg himself, it all comes back to putting a name to the habits, as only then can they be consciously altered using a technique like HRL. We all have habits that we may be embarrassed to confess to—yet understanding and applying insights from the habit loop can help normalize struggles and elicit change. 

The CAR model is not an end-all-be-all for describing every human behavior and changing the ones we want to change. Human behaviors are nuanced, not every action is habitual, and there’s always the possibility of something as powerful as habit loops being abused for harm.

Oversimplification of Complex Behaviors

Human behavior is not as black and white as simple habitual patterns. The CAR model focuses on habit loops but may overlook factors such as underlying motivations, emotions, and social influences driving behavior. For example, your issues with sleep may not be as simple as being undisciplined with bedtime—life pressures, anxieties, or cultural norms may all influence sleeping patterns. 

With the nuances and complexities of human behavior, it is worth noting that the model of the habit loop simply may not work for everyone. Individual differences in one’s ability to form good habits or break bad ones may vary considerably. Such differences speak to the CAR model’s ability to make habits appear less complicated than they actually are. In the end, how to form and change habits depends on each person—not only a theoretical loop for change.

Not Every Behavior is a Habit

Not all of your actions can be boiled down to parts of the habit loop. While the CAR model may be effective for routine, automatic behaviors, it may not fully explain conscious, goal-driven decision-making. This is where we might apply System 1 and System 2 thinking to explain the CAR model’s limits: the habit loop may assist with the maintenance of those automated System 1 behaviors, but not as much with deliberate System 2 behaviors. 

An example to consider is when you learn something new—you cannot form a habit around something you are unfamiliar with. For instance, while initially learning a new language you’ve never written or spoken, close attention and conscious thinking must be applied. Once you’ve got the basics down, then the habit loop may come into play as you continue your learning, helping a new language to become as natural as your native tongue. 

Potential for Unethical Use

The habit loop, while powerful for personal growth, can also be exploited by companies seeking to influence consumer behavior. By strategically crafting cues and rewards, businesses can create addictive cycles that prioritize profit over well-being. For instance, social media platforms use notifications as cues to trigger the action of scrolling, rewarding users with dopamine fueled by likes or new content with every refresh—keeping them engaged longer than they intended. While effective, such tactics can manipulate attention and encourage compulsive use.

This raises ethical concerns, as companies may prioritize habit formation that benefits them over the mental health or autonomy of their users. The habit loop, when used unethically, highlights the fine line between fostering positive habits and exploiting vulnerabilities. Transparency and accountability are crucial to ensure that such behavioral strategies serve users rather than trap them in destructive cycles.

Hijacking the Habit Loop to Quit Smoking

When it comes to breaking habits, health interventions often lean into the power of the habit loop to drive behavior change. Smoking, in particular, is a prime example of how deeply ingrained habit loops can keep people stuck. Stress (the cue) prompts the action of smoking, which delivers the reward of temporary relief. For decades, smoking cessation programs have sought to rewire this cycle, turning unhealthy patterns into healthier ones.

In one such effort, the American Lung Association’s Freedom from Smoking program,10 participants were guided to identify their unique triggers and consciously replace smoking with alternative actions. For example, instead of reaching for a cigarette during moments of stress, individuals were encouraged to take deep breaths, practice mindfulness, or engage in brief physical activity. This method aimed to replicate the calming reward of smoking while forming healthier, long-term habits.

The results of this approach were promising. A study examining participants showed that by focusing on cues and replacing actions, individuals significantly reduced smoking frequency over time. Gradually, the new actions became just as automatic as the old habit of smoking, illustrating the power of behavior change through intentional habit loops.

This example underscores the potential of the habit loop as a tool for health interventions. By segmenting behaviors into cue, action, and reward, professionals can help individuals transform harmful routines into healing ones, offering practical solutions that extend beyond smoking cessation to a wide range of health and wellness challenges.

Fostering Sustainable Laundry Habits with Behavioral Science

Speaking of bad habits, are you running too many loads of laundry? You’re not the only one, but behavioral science is here to help you reduce your washing and drying cycles. In this article, TDL columnist Rosa Strube breaks down the challenges of promoting more sustainable laundry habits through points on consumer engagement, behavior change campaigns, behavior models, and reluctance over cold washes. 

Cybersecurity 101 Training: How to build employee habits that prevent cyberattacks

Sometimes, our online and digital habits at work can lead to risks like phishing, cyberattacks, and other breaches in cyber security. In this article, TDL columnists Lindsay Turk, Dr. Brooke Struck, and managing director Dan Pilat explore how to address cybersecurity early and form good habits to avoid such cyberattacks.

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