Pay Attention: Mobile Slot Machines


“I feel tremendous guilt… The short-term, dopamine-driven feedback loops that we have created are destroying how society works,” admits Chamath Palihapitiya, former Facebook VP of user growth. This was in response to a question about his involvement in exploiting consumer behavior. These dopamine-driven feedback loops have been embedded in our smartphones, creating habits and shaping our behavior without us even noticing them. In order to maximize profit, mobile product designers have harnessed the addictive potential of techniques such as variable ratio reward schedules to manipulate user behavior and capture more engagement for advertisers.

Understanding Dopamine & Addiction

Before we can talk about variable ratio reward schedules, it’s important to first understand what dopamine is and how addiction works. Dopamine is a feel-good neurotransmitter that is released by the brain when eating delicious food, during sex, after exercise, after successful social interactions, or using drugs. Its main purpose is to motivate behavior by rewarding us with enjoyable sensations. While dopamine isn’t the sole cause of addiction, its motivational properties are thought to play a role in addiction.

So how does addiction form? A Harvard Health article titled “Understanding Addiction” reports: “According to the current theory about addiction, dopamine interacts with another neurotransmitter, glutamate, to take over the brain’s system of reward-related learning. This system has an important role in sustaining life because it links activities needed for human survival (such as eating and sex) with pleasure and reward… Repeated exposure to an addictive substance or behavior causes nerve cells in the nucleus accumbens and the prefrontal cortex (the area of the brain involved in planning and executing tasks) to communicate in a way that couples liking something with wanting it, in turn driving us to go after it.”

Basically, in this process, dopamine is released to link substances or behaviors that make us feel good with the desire to take action and seek out that pleasure. Over time, repeated exposure to the substance or behavior causes a tolerance to develop, and the brain adapts in a way that makes the substance or behavior less pleasurable. The Harvard Health article continues: “At this point, compulsion takes over. The pleasure associated with an addictive drug or behavior subsides–and yet the memory of the desired effect and the need to recreate it (the wanting) persists.”

Dopamine Triggers

Now, some might argue that you can’t get addicted to your phone–after all, it isn’t an addictive substance like caffeine, nicotine, or alcohol. I used to think the same thing. However, neurobiology research technician Trevor Haynes begs to differ: “Cognitive neuroscientists have shown that rewarding social stimuli–laughing faces, positive recognition by our peers, messages from loved ones–activate the same dopaminergic reward pathways. Smartphones have provided us with a virtually unlimited supply of social stimuli, both positive and negative. Every notification… has the potential to be a positive social stimulus and dopamine influx.” Thus, repeated exposure to apps that utilize such social stimuli in their reward systems can cause dopamine influxes that result in habit-forming. When a certain behavior (such as a finger swipe) is associated with positive social stimuli (and consequently the release of dopamine), the brain is building connections that motivate the individual to repeat that behavior. Over time, these habits can turn into addiction.

Furthermore, it’s not only substances or behaviors that you can get addicted to. In fact, social psychologist Jeanette Purvis points out that “In a study on the brains of drug addicts, researchers found that the expectation of the drug caused more release of the feel-good neurotransmitter dopamine than the actual drug itself.” This works the same with any reward, not just with drugs. Once you’ve come to associate a certain activity with pleasure, just the anticipation itself can be enough to raise dopamine levels.

This is actually a feature of our dopamine neurons called reward prediction error encoding. According to Haynes, “These prediction errors serve as dopamine-mediated feedback signals in our brains. This neurological feature is something casino owners have used to their advantage for years. If you’ve ever played slots, you’ll have experienced the intense anticipation while those wheels are turning–the moments between the lever pull and the outcome provide time for our dopamine neurons to increase their activity, creating a rewarding feeling just by playing the game.”

The Machine Zone

This rewarding feeling of anticipation is one that is familiar to slot players, and is referred to as the ‘machine zone’, by social anthropologist Natasha Dow Schull. While talking with gamblers and casino operators in Vegas for her research, Schull discovered that most slot players aren’t playing to win or even to make money. Rather, it’s all about getting into the zone. So what’s so alluring about this ‘zone’ that makes people willingly play slots over and over when they know they’re losing money? One player attests: “‘Everything else falls away… A sense of monetary value, time, space, even a sense of self is annihilated in the extreme form of this zone that you enter.’” Others described it like this: “‘You’re in a trance, you’re on autopilot. The zone is like a magnet, it just pulls you in and holds you there.’” To these players, the reward itself isn’t what keeps them playing; rather, it’s the expectation of the reward when the wheels are spinning that players are hooked on.

In an Atlantic article examining Schull’s findings, writer Alexis Madrigal proposes: “The machine zone is the dark side of ‘flow’, a psychological state proposed by Mihaly Csikszentmihalyi. In a flow state, there is a goal, rules for getting to the goal, and feedback on how that’s going… Csikszentmihalyi described the state like this: ‘Being completely involved in an activity for its own sake. Importantly, the task has to match your skills, so there’s a feeling of ‘simultaneous control and challenge’… The ego falls away. Time flies. Every action, movement, and thought follows inevitably from the previous one, like playing jazz.’”

Flow can happen as part of everyday life, but may be most familiar during activities such as writing, making art, playing sports, gaming, learning, or working. For example, with music, it usually takes me days, sometimes months to finish writing a single song. But sometimes, just sometimes, I’m able to complete a whole song in a single day. The words and rhythms come to me naturally, while hours pass by quickly without even realizing it. In this state, I feel like I’m able to pull off what almost superhuman feats I usually would be unable to accomplish. Athletes often describe this feeling of ‘flow’ as being ‘in the zone’.

The ‘zone’ that athletes enter during a heated match and the ‘machine zone’ that gamblers enter in front of slot machines are two sides of the same coin. However, as Madrigal points out: “Instead of the self-fulfillment and happiness that Csikszentmihalyi describes, many gamblers feel deflated and sad about their time on the slots. The games exploit the human desire for flow, but without the meaning or mastery attached to the state. The machine zone is where the mind goes as the body loses itself in the task.” While an athlete feels fulfilled from playing at their best, or an artist feels fulfilled from creating a work of art, gamblers don’t get that sense of fulfillment after being in flow. Instead, they’re left feeling regretful, since the activity itself was devoid of meaning.

The Smartphone Zone

Okay, but what does all this about the machine zone have to do with smartphone apps? Well, the use of reward prediction errors and ‘the machine zone’ are actually embedded in the design of many mobile apps we use on a daily basis. Such apps, especially social media platforms such as Facebook, Snapchat, Twitter, TikTok, Instagram, and Tinder (just to name a few), employ techniques that cause users to enter some softer version of the machine zone. If you’ve used one of these apps before, you probably recognize the machine zone yourself.

Of course, you’re likely not in that zone when you’re just chatting with your friends on Instagram, but if you catch yourself mindlessly scrolling down your feed for an extended period of time… You’re probably in that zone. Madrigal elaborates: “The machine zone is anti-social, and it’s characterized by a lack of human connection. You might be looking at people when you look through photos, but your interactions with their digital presences are mechanical, repetitive, and reinforced by computerized feedback.” And since the activity of scrolling through a smartphone lacks much meaning or mastery, it’s likely you’ve left this zone feeling unfulfilled, regretful of wasted time.

These mechanical, repetitive interactions are not only reinforced by computerized feedback, but also with dopamine. Each interaction, finger swipe, or tap is associated with some type of reward and a dopamine influx, whether it’s getting a new message, more content your feed, or a potential match on Tinder. This system has been employed by designers with the intent of creating habit-forming dopamine loops for users. Purvis warns, “For those who may be expecting the next swipe on Tinder to lead to reward, serial swiping can start to look and feel a lot like addiction… In terms of psychological conditioning, Tinder’s interface is perfectly constructed to encourage this rapid swiping. Since users don’t know which swipe will bring the “reward” of a match, Tinder uses a variable ratio reward schedule, which means that potential matches will be randomly dispersed.” Many apps implement this reward pattern, which is optimized to keep users as engaged as possible.

Variable Ratio Reward Schedules

The variable ratio reward schedule was introduced by B.F. Skinner in the 1930’s and is a proven method for creating addictive habits. Haynes explains, “In his experiments, he found that mice respond most frequently to reward-associated stimuli when the reward was administered after a varying number of responses, precluding the animal’s ability to predict when they would be rewarded. Humans are no different: if we perceive a reward to be delivered at random, and if checking for the reward comes at little cost, we end up checking habitually. If you pay attention, you might find yourself checking your phone at the slightest feeling of boredom, purely out of habit. Programmers work very hard behind the screens to keep you doing exactly that.” This means that compared to receiving a reward every time a task is completed, if we receive a reward only sometimes a task is completed, we are more likely to repeat that task many more times.

In fact, variable ratio reward schedules are so effective at building habits that, to quote Purvis, “It’s the same reward system used in slot machines, video games and even during animal experiments where researchers train pigeons to continuously peck at a light on the wall.” However, its uses don’t end there. Product designers have also picked up on the power of variable ratio reward schedules, as Silicon Valley insider and technology ethicist Tristan Harris attests during an 60 Minutes interview with Anderson Cooper: “Every time I check my phone, I’m playing the slot machine to see, ‘What did I get?’ This is one way to hijack people’s minds and create a habit, to form a habit. What you do is you make it so when someone pulls a lever, sometimes they get a reward, an exciting reward. And it turns out that this design technique can be embedded inside of all these products.”

Harris is right; design techniques that utilize variable ratio reward schedules such as the pull to refresh, the infinite scroll, notifications, recommendation algorithms, and gamification have become more prevalent in mobile apps. In fact, pull to refresh is one of the earliest examples of variable ratio reward schedules on the internet. The action of pulling down with the finger is like pulling a lever, the refresh wheel spins just like the slot wheels do, and you either get nothing or a reward (new emails). Since access to pulling to refresh comes at little cost, it’s easy for users to check habitually.

The infinite scroll is basically the older brother of pull to refresh, on steroids. When you pull to refresh once, there isn’t much point in refreshing it again until waiting for a bit, since it’s unlikely to have any new updates soon after. However, the infinite scroll rewards the user over and over with an endless supply of content. Every swipe of the finger down your feed is a pull of the lever on the slot machine. Criticizing the use of techniques such as the infinite scroll, Ramsay Brown, who writes computer code designed to provoke a neurological response for apps, attests: “You spend half your time on Facebook just scrolling to find one good piece worth looking at. It’s happening because they are engineered to become addictive… Since we’ve figured out, to some extent, how these pieces of the brain that handle addiction are working, people have figured out how to juice them further and how to bake that information into apps.”

Notifications are one of the worst offenders of this reward system because they interrupt you in the real world to drag you back into the digital world. Notifications also employ a variable ratio reward system because every time you hear a notification, you have no idea what it might be. It could be something important or pleasant, such as a text from a friend or a like on your photo, but on the other hand, it might just be Uber Eats telling you to order delivery again tonight. Every time you grab your phone and open the lock screen to check your notifications, you’re playing that slot machine to see what reward you got.

More recently, features like Snapchat Stories have utilized this reward pattern in an even more effective way. Now, you can click on people’s profile photo to see a few seconds of a full-screen photo or video that stays up for 24 hours. Once you’re in this full-screen mode, every tap flicks to the person’s next story, and once that person’s story runs out, it goes to the next person’s stories. Furthermore, even if you don’t tap the screen at all, the stories will auto play every few seconds on their own. Each new story is the pull of a lever that results in a full-bleed experience. Now, platforms like Instagram, Facebook, and even YouTube have integrated this same stories feature into their platforms.

Once you recognize the variable ratio reward system, you’ll start seeing it everywhere in the features of social media platforms.

The Price We Pay

Now you might be asking what’s so bad about all this, anyways? At the end of the day, spending an extra hour or few on your phone can’t be that big of a deal. Well, the truth is, frequently receiving a large amount of dopamine from these apps can cause dopamine exhaustion. This is a phenomenon in which the brain is so chronically used to a high level of dopamine that it builds up a tolerance in order to maintain homeostasis. The brain essentially has to ‘turn down the volume’ of the dopamine input; as a result, individuals in this state do not receive as much dopamine as they typically would from other activities (e.g. social gatherings) outside of the app. One might conclude “I don’t like X Y or Z because it’s not as fun as looking at my phone”, but it is important to understand this is due to a change in the person’s neurochemistry.

Aside from dopamine exhaustion, the potential for addiction itself is reason enough to be cautious. Even if the addictive activity may not be inherently harmful, anything in excess can negatively affect one’s life. Freelance writer Whitney Morgan puts it better than I could: “Time you should be spending working, driving, chatting with a friend…Too much of anything can evolve into an addiction, even if it’s something healthy like doing Crossfit. Dad’s not home for dinner for the 6th day this week…Crossfit is more important. It’s healthy for his body but not for his role as a father. Not for his family. Sex is great. But there are such things as sex addicts. When it impairs your day to day life, it’s an addiction. When it keeps you from doing things you need to do, it’s an addiction.” And personally, I can easily recall instances where my phone was keeping me from doing the things I needed to do.

The Illusion of Free Choice

Okay, but don’t users make their own decisions? If someone is spending all this time on their phone, it’s surely by their own doing, right? Well, yes, but we also have to acknowledge that users also have psychological vulnerabilities that designers take advantage of to manipulate behavior. When I go down a YouTube rabbit hole, I indeed am at fault for binging all of those videos without stopping myself. However, I didn’t click on the first video with the intention of spending two hours watching Curb Your Enthusiasm memes. On the other side of the screen, designers have created tools like autoplay and devised increasingly effective recommendation algorithms to make it easier for users to slip into the machine zone, and into compulsion. Consumer behavior expert Nir Eyal explains in his book Hooked: ‘The technologies we use have turned into compulsions, if not full-fledged addictions. It’s the impulse to check a message notification. It’s the pull to visit YouTube, Facebook, or Twitter for just a few minutes, only to find yourself still tapping and scrolling an hour later.”

In Tristan Harris’s viral presentation at Google, “A Call To Minimize Distraction and Respect User’s Attention”, he addresses how technology which encourages compulsion leads to mindless behavior: “Humans make different decisions when we pause and consider, versus when we react immediately. When access to the next hit is too frictionless, we lose the ability to consider before acting. When scrolling is frictionless, we don’t think before we flick to see what’s next. Or when it’s so frictionless, we don’t think before we grab our phone after it buzzes. Or so frictionless, we don’t think before getting a snack after an urge. When we lose that moment to consider before acting on our impulses, we lose what sets us apart as thinking humans.” Over time, the systems in our smartphones have become more frictionless and easier to use. But are we still the ones in control, or are we falling victim to compulsion? Is it the designers that are thinking and making decisions for us instead?

Let’s go back to the gambling analogy. On the podcast Your Undivided Attention, Natasha Dow Schull explains to Tristan Harris how casino architects use design to lead guests towards the slot machine areas: “The whole interior design and architecture of the casino is really constructed and engineered, I learned, to get people over to these profit hubs… A casino interior designer told me, ‘Look at the floor’. The floor is so important, because people sort of wander in off the strip, and the carpet is doing a huge amount of work. The carpet is drawing them into the gaming areas…. narrowing at the right point, and never, never having right angles in them. It is very important not to have right angles in the carpets because what a right angle does is it stops you up, and puts you in the position of a decision maker.” Similarly, product designers look to avoid ‘right-angles’ that put users in the position of a decision maker. Here, the curvature of the carpet is analogous to the frictionless nature of apps that lead us to compulsion.

In his 60 Minutes interview, Tristan Harris “likens the power of design to manipulate user choices to a magician’s misdirection: ‘we ignore how… [our] choices are manipulated upstream by menus we didn’t choose in the first place… This is exactly what magicians do. They give people the illusion of free choice while architecting the menu so that they win, no matter what you choose.” More simply put, in another interview for Wired, he words it this way: “The problem is the hijacking of the human mind: systems that are better and better at steering what people are paying attention to, and better and better at steering what people do with their time than ever before”.

Silicon Valley’s Business Model

In his blog post titled, “Do product designers need a code of ethics?”, Dropbox employee David Vallance boldly states: “The transition from technology to compulsion to addiction is not accidental. It is the result of conscious design decisions.” But why are product designers so intent on using techniques that manipulate user behavior and lead users into compulsion? Simply put: because we don’t pay for the products we use, advertisers pay for the products we use. Advertisers are the customers. We get to use them for free because our eyeballs are the things being sold.

As a result, the business models of these tech companies revolve around keeping users engaged on the screen as much as possible in order to turn a profit. The more attention that can be captured, the more that ad space can be sold to advertisers. Furthermore, the more time you spend on an app, the more data can be collected, which is used to get better at keeping users on the app and more accurately match target audiences to advertisers.

Similarly, casino designers are also trying to keep consumers as engaged with the slot machines as possible to maximize profits. Schull questions this relationship between designer and consumer with the analogy of an assembly line: “So this curvature that I mentioned on the carpet floors carried over to the curvature of these ergonomic seats which are designed especially for the elderly to allow the flow of blood through the arteries. It’s very reminiscent of 19th century factory construction assembly lines, how to prune out dead time and increase productivity. In fact, I’d say the rhetorical analogy for the machine zone is what the casinos call, this is the actual term, continuous gaming productivity. So although these are consumers, they are in an analogous position to the factory worker on the assembly line.” In the same way, consumers of mobile apps are also in an analogous position to the factory worker. Users of an app produce attention that is sold to advertisers, while product designers tinker with algorithms and addictive elements to increase worker productivity.

“This system works for everyone involved at first glance, but it has created an arms race for your attention and time. Ultimately, the winners of this arms race will be those who best use their product to exploit the features of the brain’s reward systems.” What Haynes means here is this system has created a negative feedback loop where mobile apps are designing more and more addictive products to compete for user attention from one another. This can be seen in the widespread use of video autoplay, the pull to refresh, the infinite scroll, the increasing number of notifications and interruptions, and increasingly personalized recommendation algorithms. Madrigal rebukes designers’ disregard to properly understand or address their users’ actual needs: “Because designers and developers interpreted maximizing ‘time on site’, ‘stickiness’, ‘engagement’, as giving people what they wanted, they built a system that elicits compulsive responses from people that they later regret.”

The Influence & Responsibility of Product Designers

Since the inception of the internet, designers have become increasingly capable of reaching large numbers of people on a global scale. Furthermore, with the rapid rate technology has evolved in recent years, smartphones and the internet have become the core of many of our everyday activities and interpersonal relationships. According to David Vallance, “Fifty years ago, the effect of poor design was minimal… In comparison, modern designers can tinker with the very fabric of society. A single keystroke change to Facebook’s algorithm can influence the news that tens of millions of people see.” Since the influence and reach of designers has grown to touch a larger audience, so has the weight of each decision that designer makes. However, it seems product designers have been disregarding the butterfly effect their actions can cause.

Whether product designers are aware of these outcomes and whether they care or not is unclear. However, Tristan Harris reminds us: “Inadvertently, whether they want to or not, they are shaping the thoughts and feelings and actions of people. They are programming people. There’s always this narrative that technology’s neutral. And it’s up to us to choose how we use it. This is just not true.” Some of the techniques like the ones I mentioned earlier may not have been created with insidious intent. However, designers have since realized the effectiveness of such addictive design elements and have been honing their use because ultimately, they work.

Design director Mike Monterio echoes Harris’s sentiment in a warning: “‘Designers have been running fast and free with no ethical guidelines.. And that was fine when we were designing posters and sites for movies. But now design is interpersonal relationships on social media, health care, financial data traveling everywhere, the difference between verified journalism and fake news. And this is dangerous.’” Without any design philosophies or ethical guidelines for designers, we vaguely hope designers are acting in our best interests. However, left to their own devices, designers looking to maximize revenue have utilized techniques such as variable ratio reward schedules, stolen from casinos to produce addictive software.

Bad Design vs. Unethical Design

Bad design can be painful, but is usually caused by a designer’s carelessness or ignorance, On the other hand, unethical design is purposefully engineered to take advantage of the psychological vulnerabilities of users. There has been an increasing prevalence in the use of dark patterns, user interfaces carefully crafted to trick users into doing something they might not mean to (e.g. signing up for a subscription). If you were to Google ‘dark patterns’, you would find some egregious examples that are obviously evil. However, the most dangerous dark patterns are the ones that are unnoticeable, embedded in our daily lives.

Tristan Harris questions the use of such techniques in his 60 Minutes interview: “[Snapchat] invented this feature called ‘streaks’, which shows the number of days in a row that you’ve sent a message back and forth with someone… But it turns out that kids actually when they go on vacation are so stressed about their streak that they actually give their password to, like, five other kids to keep their streaks going on their behalf. And so you could ask when these features are being designed, are they being designed to most help people live their life? Or are they being designed because they’re the best at hooking people into using the product?”

Many of those born in Generation Z may not even remember when the internet wasn’t always around. Every generation from now on won’t know what life is like without a smartphone in their pocket that’s connected to the internet, 24/7. Nowadays, I see parents letting their kids play with phones and iPads as soon as they’re old enough to touch a screen. When I consider the ultimate goal of these apps is to capture as much attention as possible for profit, I can see their intentions are not best aligned with the long-term health of users. Though a bit ironic coming from someone born in the Silicon Valley in 1999, it makes me feel uncomfortable to think these devices are raising children from such a young age.

What Can We Do?

So, is there anything we can do? Well, as users, we can try to be more conscious of our decisions and activities when we’re using our phones. Furthermore, you can do things like turn off notifications for unimportant apps, or delete apps that promote addictive behavior. If you’re hesitant to completely turn off notifications, you can try to disambiguate your notifications by changing the sound of important notifications. This way, you’ll be able to tell when you’re getting an important message, and can rest assured that other notifications are not urgent. Other than notifications, taking breaks from screen use or spending less time on your phone altogether is probably the best way to go.

However, there’s a limit to what we can do as users. As designers, we have a responsibility to our users to consider how the products we build are changing the way people live their lives, for better or worse. Instead of focusing on only the immediate consequences of a decision, David Vallance recommends designers utilize second-order thinking to think about subsequent long-term consequences of their actions. When applying this technique, you might find decisions that seem positive in the short term can often be negative in the long run. On the other hand, co-founder of the Center for Humane Technology Tristan Harris recommends “designers purposefully ask themselves how they can respect the timing, frequency, and duration of a product’s use to align with the user’s ideal life.” If a feature (e.g. Snapchat streaks) is not helping the user achieve their ideal life, it should be removed.

What’s interesting about all these addictive design techniques I’ve mentioned is that the same techniques and neuroscience can be used to promote positive behaviors, such as working out or studying. Therefore, these technologies for engagement can be used for good, or can be used for evil. Looking to the future, it’s up to mobile product designers to shape the ways we interact with our smartphones for the better.

Works Cited

Cooper, Anderson. “What is ‘Brain Hacking?’ Tech Insiders on Why You Should Care.” 60 Minutes, April 9, 2017, Accessed April 8, 2021.

Harris, Tristan. “A Call to Minimize Distraction & Respect Users’ Attention.” A Call to Minimize Distraction. 2013, Accessed April 8, 2021.

Harris, Tristan & Raskin, Aza. “What Happened in Vegas.” Your Undivided Attention, Center for Humane Technology, June 10, 2019,

Haynes, Trevor. “Dopamine, Smartphones, & You: A battle for your time.” Science in the News — Harvard University, May 1, 2018, Accessed April 8, 2021.

“How Gaming Affects Dopamine Reward Circuitry.” Youtube, Uploaded by HealthyGamerGG, January 25, 2019,

Madrigal C. Alexis. “The Machine Zone.” The Atlantic. July 13, 2013, AccessedApril 8, 2021.

Morgan V. Whitney. “A Social Psychologist Explains How Tinder has Become a Real Addiction.” Medium, September 6, 2017, Accessed April 8, 2021.

Purvis, Jeanette. “Why Tinder is so ‘evilly satisfying’.” The Conversation, February 10, 2017, Accessed April 8, 2021.

“Understanding Addiction.” Harvard Health Publishing, July 2011, Accessed April 8, 2021.

Vallance, David. “Do product designers need a code of ethics?” Dropbox Blog, May 20, 2019, Accessed April 8, 2021.