Why you can't stop scrolling: the science of 'dark flow'

Summary

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Short Wave Podcast Summary

Episode: Why you can't stop scrolling: the science of 'dark flow'
Host: Emily Kwong
Guest: Michaeleen Doucleff, Science Journalist
Date: June 1, 2026
Duration: ~15 minutes

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Episode Overview

This episode digs into why it’s so hard to put down your smartphone, exploring the psychological tactics behind app design that keep users endlessly scrolling. Drawing on her new book Dopamine Kids, guest Michaeleen Doucleff discusses with host Emily Kwong the concept of "dark flow"—a trance-like, addictive state similar to what gamblers experience with slot machines. Together, they break down how these tactics migrated from Las Vegas casinos into social media and gaming apps, revealing the four key features engineered to hijack your attention. The conversation also includes practical strategies to disrupt these habits.

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Key Points & Insights

1. The Roots of Addictive App Design in Gambling (03:55–06:47)

• Origins in Casinos:

  • In the 1980s, Las Vegas casinos replaced traditional slot and poker machines with digital, video-based versions.
  • The industry conducted massive, real-time behavioral experiments—“large scale AB testing”—on gamblers to optimize the games’ addictiveness.
  • Tactics included lights, sounds, and ergonomic features, continually tweaked to keep people playing longer.
  • Memorable moment (05:49): Some gamblers wore adult diapers so they wouldn't need to leave the machines:

    "One casino worker told her that each night a bunch of the machines sit out in an alley for cleaning because people have peed in them." – Michaeleen Doucleff (05:49)

• Machine Zone/Dark Flow:

  • Anthropologist Natasha Dow Schüll identified a “machine zone,” where players lose track of time and surroundings.
  • This state is not exclusive to gambling: “Apps on phones can sometimes trigger this same machine zone state.” (06:12)

2. The Four-Ingredient Recipe for Digital 'Super Glue' (06:54–11:19)

Michaeleen and Natasha Dow Schüll lay out the “super glue recipe” for addictiveness in apps:

a. Solitude (06:59–07:38)

• Using apps alone removes social cues that might help us realize when to stop.

• "When we use an app by ourselves, we have trouble noticing if we're actually enjoying what we're doing or even realizing when what we're doing is hurting us in some way." – Michaeleen Doucleff (07:10)

b. Bottomlessness (07:44–08:25)

• Endless feeds: content auto-loads without natural stopping points.

• “There is no natural stopping point.” – Natasha Dow Schüll (07:57)

• Emily notes,

  "I genuinely feel like I'm being baited like a fish… I just have to keep watching." (08:09)

c. Speed (08:31–09:14)

• Faster interaction (like infinite scroll) means people stay longer.

• "On slot machines, you can play, like, 1200 games per hour or, like, one game every three seconds. It's bonkers." – Michaeleen Doucleff (08:33)

d. Personalization/Teasing Algorithm (09:46–11:08)

• Algorithms keep you hooked by getting closer to what you want, but never fully satisfying your cravings.

• "Giving you what you want will get you off the app. They don't want that." – Dr. Jonathan Morrow (10:17) "When you see improvement, progress, and so on, then you have a huge spike of dopamine telling you, oh, do it again and you will get it." – Dr. Mateusz Gola (10:43)

• Summary:

  “The social media super glue recipe is as follows: Solitude, bottomlessness, speed, and teasing.” – Emily Kwong (11:12)

3. Dark Flow vs. Good Flow (11:31–12:32)

• Good Flow:
  • The classic, productive “flow” state (as described by Mihaly Csikszentmihalyi) enhances well-being and results from complex, challenging tasks like playing music or sports.
  • Leaves you feeling happy and optimistic.
• Dark Flow:
  • Triggered by mindless, repetitive tasks (e.g., endless scrolling).
  • Afterward, you feel lethargic or even gloomy.

  • “These apps create dark flow. That's where you're concentrating on an easy, kind of mindless task, and you still feel deeply immersed... But afterwards, you often feel bad.” – Michaeleen Doucleff (12:12)

4. Fighting Back: Breaking the Spell (12:50–13:53)

• Practical Tips:
  • Create “bottoms” and “speed bumps” (e.g., cancel streaming subscriptions and pay per view a la carte).
    • Michaeleen found she and her family consumed far less content and saved money:

      “If we cut back on our movie watching, I'd say like a tenth.” (13:22)

  • Stop carrying your phone everywhere at home.

    “When you come home, put your phone in a drawer near the door and leave it there... I guarantee you it'll change your life.” – Michaeleen Doucleff (13:41)

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Notable Quotes & Moments

• On the process of addictiveness (05:13):
  “The casinos essentially ran these large scale experiments... They tweaked the device a bit and then see if those changes increase the time people spent gambling.”

• On the root of app design (04:43):
  “They're like apps with giant touchscreens and these ergonomic chairs attached to them. Plus they added all these things to capture your attention.”

• On what keeps us glued (10:17):
  “Giving you what you want will get you off the app. They don't want that.” – Dr. Jonathan Morrow

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Key Timestamps

• Main story starts: 03:55
• Origins of digital slot machines: 04:01–06:06
• ‘Machine zone’ state: 06:12–06:47
• The four ingredients: 06:54–11:19
• Classic flow vs. dark flow: 11:31–12:32
• Practical solutions: 12:50–13:53

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Final Thoughts

This episode offers an illuminating and sometimes startling look at how attention-hijacking designs from the gambling world are now ubiquitous in the apps we use every day. Pairing lively banter with expert testimony, Emily Kwong and Michaeleen Doucleff unpack the mechanics of digital dependence and provide simple, actionable strategies to disrupt it—making this essential listening for anyone with a smartphone.

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Transcript

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[B]

You're listening to Shortwave from NPR. Hi, Short Wavers. Emily Kwong here with NPR alum, now independent science journalist Mike Lean Duclef. Hi, Mike Lean.

[C]

Hi, Emily.

[B]

I hear you have a new book out now about the science behind screen time.

[C]

I do. It's called Dopamine Kids. And in one part of it, I explore why so many of us, including myself, can't put down our darn phones.

[B]

It's awful. Yeah. I pick up my phone to do one thing and suddenly I'm on social media for 20 minutes. I don't know how that happens.

[C]

Yeah, for me, Emily, it feels like there's this kind of super glue on the phone holding me there. Turns out that feeling isn't accidental. Many apps are designed to do this.

[B]

And this has kind of come to light in the courts, too. There have been two landmark trials this year in which tech companies were found guilty of harming children through their apps. And specifically the California case found Instagram owner Meta and Google's YouTub who deliberately designed their apps to be addictive for kids.

[C]

Yeah, and the companies are appealing those verdicts. But scientists have already spent more than a decade identifying the exact features that tech companies use to keep us glued to apps for as long as possible. So, Emily, I have for you today the super glue recipe. As the anthropologist Natasha Dal Shaw puts

[D]

it, things that keep us, you know, spending more time, spending more money, draining more of us and our energy and ourselves what might literally prevent flourishing.

[B]

Yes, this is what social media addiction and like obsession sounds like. But these features, they have a surprising history, I hear.

[C]

Yes, they have deep roots in the gambling industry.

[B]

So today on the show, we are digging into the design of your favorite phone app and learning how tech companies mimicked and the gambling industry to keep us scrolling and staring. I'm Emily Kwong.

[C]

I'm Mike Lane Duclef and you're listening to Short Wave, the science podcast from npr.

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[B]

So this story begins in the casinos of Las Vegas. Take us back in time and explain what was happening there.

[C]

Yeah, so we're going to rewind 40 years ago, way back in the 1980s, when the casino industry underwent a massive transformation and created what many scientists think is the most addictive form of gambling ever.

[B]

Oh, how did they do that?

[C]

So they went around and ripped up nearly all the mechanical slot machines and all those green felt poker tables and replace them all with digital versions of these games. So video based slot machines, video based poker machines?

[B]

Oh no.

[C]

They did this because these machines were way cheaper to maintain. But also they allowed the casino industry to add in all these extra features to them.

[B]

It's like they were apps before they were apps. The the gambling games just played on screens.

[C]

That's right. They're like apps with giant touchscreens and these ergonomic chairs attached to them. Plus they added all these things to like capture your attention and hold you there like lights, sounds, flashing images. So over the course of about 20 years, the industry gradually and purposely increased the addictiveness of these games by tweaking their features based on user feedback.

[B]

Wait, who gave the user feedback?

[C]

The gamblers. The casinos essentially ran these large scale experiments on all the millions of people gambling each year in Vegas. They tweaked the device a bit and then see if those changes increase the time people spent gambling, then they just repeated the process for decades.

[B]

So they were performing essentially massive AB testing on gamblers?

[C]

Pretty much. And the result was Truly extraordinary. The industry created devices that some people stay on for remarkable periods of time, 24 hours, 48 hours uninterrupted.

[B]

Like they don't even stop to use the bathroom sometimes.

[C]

Not that. Anthropologist we just heard from, Natasha Dalcholl, found that some people wear adult diapers to the casino so they don't have to stop gambling. One casino worker told her that each night a bunch of the machines sit out in an alley for cleaning because people have peed in them.

[B]

That is awful. That makes me so sad to hear, because it just shows the power these devices have on people's attention.

[C]

Yeah. And the power they have on people's time and money as well. In her 15 years of researching, Natasha found four features that when combined together, can trigger a trance like state in people. You lose track of time, where you are, what you're doing. Scientists call this the machine zone or dark flow. And some people have a really hard time stepping away from a device when they're in this state. And Natasha realized that apps on phones can sometimes trigger this same machine zone state. So she started to analyze the design of apps, social media, games, in the same way.

[D]

You know, I could never have anticipated this. I think gambling offers a case study of what big tech does in a more general way.

[B]

Mike Lean, let's blow the COVID off of this. What are the four ingredients in social media? Super glue.

[C]

Okay, so the first ingredient is solitude. You use the app alone. It's just you and the screen.

[D]

This is important because it removes social cues for stopping.

[C]

When we use an app by ourselves, we have trouble noticing if we're actually enjoying what we're doing or even realizing when what we're doing is hurting us in some way.

[B]

So you're saying it's the presence of other people that helps pull us out of that machine zone state?

[C]

That's right. And this, Emily, is real people, not virtual people. Studies have found that when kids use screens all alone in their bedroom, they're more likely to stay on the app, even when it prevents them from going to sleep or interferes with their homework or friendships.

[B]

I've experienced this as an adult. Okay, what is the second ingredient to social media? Super gloom.

[C]

It's what I call bottomlessness. There's just seemingly endless photos, endless videos, endless comments to read, endless levels to reach on games. And as Natasha points out, all this content appears automatically.

[D]

There is no natural stopping point.

[C]

So as you're scrolling, you may have a little thought in your head, like, maybe I should go to sleep. Right. But then another outrageous video Pops up and in your feed.

[B]

I genuinely feel like I'm being baited like a fish and that it's not totally within my control for some reason, and I just have to keep watching. And I think it's because I just. There's this feeling of, well, if I just stick around, something else will happen, and I won't be totally satisfied if I leave now.

[C]

Exactly. And that feeling grows even stronger when you add in the third ingredient, which is speed.

[B]

Ah, right.

[C]

The gambling industry found that when people could place bets faster and faster, they gambled longer and longer. Today, on slot machines, you can play, like 1200 games per hour or, like, one game every three seconds. It's bonkers.

[B]

Wait, what? And the speed thing, you're saying this has been happening for a long time with casino games, and it's definitely happening on social media?

[C]

Oh, yeah, for sure. The faster we can scroll, the longer we stay on. These apps, Infinite scroll and Autoplay let us view new content faster and more smoothly because you don't have to stop and click. When social media companies added Infinite scroll in the 2010s, they There was a huge jump in use.

[B]

Do scientists know why that's the case? That moving faster would make us stay on the app longer?

[C]

Yeah, you know, scientists don't know yet. But Natasha suspects the speed can cause

[D]

this sense where you feel like you kind of don't have a sense of where you begin and the machine ends, and it really just pulls you into this flow.

[B]

I don't like that. I don't want to be hooked up to a machine.

[C]

Yeah, I mean, Natasha says you can have this feeling that you sort of merge with the script.

[B]

I don't like it.

[C]

Me neither. So, Emily, can you guess what the fourth ingredient is? I'll give you a hint. AI is really good at it.

[B]

Oh, you mean the algorithm.

[C]

Yes. The fourth ingredient is a personalized algorithm and how it selects content for you.

[B]

Yes, it does.

[C]

Neuroscientist Jonathan Morrow studies addiction at the University of Michigan. He thinks this ingredient is probably the most important, and he explained how it works. First, the app uses AI to determine what you want to see.

[F]

They know what you want. They're very good at figuring that out.

[C]

But then this is key.

[F]

They don't give it to you. They give you something close to that.

[C]

Then a few clicks later, the algorithm gives you something even closer.

[F]

Giving you what you want will get you off the app. They don't want that.

[B]

They don't want that. They want you to stay on the app as long as Possible. All the features are designed to do that.

[C]

Exactly. So they sort of tease you in a way, right?

[B]

Yeah. They're not trying to satisfy you.

[C]

The app makes you feel like you're making progress or getting closer to your goal. Mateusz Gola is a neuroscientist at UC San Diego. He says when people feel like they're making progress, they double down their effort and try harder.

[F]

When you see improvement, progress, and so on, then you have a huge spike of dopamine telling you, oh, do it again and you will get it. Yeah. Because in the real life, when we try again, this dopamine really motivates us to get closer, closer, closer, and hit it.

[B]

So he's saying just a sense of progress, even if it's not true. Progress motivates us to keep trying and to stick with the app because it's just enough.

[C]

Yeah. There's always this possibility. Right. Of getting what you want.

[B]

So the social media super glue recipe is as follows. Solitude, bottomlessness, speed, and teasing.

[C]

Yep. When all those things combine together, you're likely to enter that trans, like state called the machine zone or dark flow. And for many people like me, it's hard to pull out of that state.

[B]

I mean, it seems to me like the tech companies and the gambling industry is hacking human minds. You know, everyone is susceptible to this but question. Mike Lean. I thought being in a flow state was good. Isn't that where you're so immersed in a task and you're enjoying it so much that you almost forget where you are and you play the piano for hours?

[C]

Yeah. So that's the, like, classic flow state. You know, the one that the psychologist Mihaly Csikszentmihalyi described back in the 80s. People go into these good flow states when they're doing complex and challenging tasks, like playing the piano or knitting a sweater, biking over tough terrain Right afterwards, this type of flow leaves you feeling really good and optimistic and relaxed.

[B]

Yeah, you get a little mood bump.

[C]

Exactly. It's like your most euphoric state or something. Yeah. But these apps don't create that. These apps create dark flow. And that's where you're concentrating on an easy kind of mindless task, and you still feel deeply immersed in it. Right. But afterwards, you often feel bad. Right. Lethargic and maybe even gloomy.

[B]

This is fascinating to me. I didn't realize there were two types of flow and that social media is very good at the machine zombie. One final question. Can we use this super glue recipe to fight back and pull ourselves away from these apps.

[C]

Absolutely. So, for example, our family was wasting way too much time on streaming apps, right? Streaming videos. So we put a bottom on the app and slowed it way down.

[B]

How'd you do that?

[C]

We canceled all of our subscriptions and now have to buy each video a la carte. I thought we'd end up spending way more money, but actually we save so much money because we're really careful about what we watch. Before we press play, we really think to ourselves, hmm, do I really Want to spend 5.99 on this video?

[B]

Wow.

[C]

Yeah. If we cut back on our movie watching, I'd say like a tenth.

[B]

You never binge when you have to pay for it each time. These are great. Any other tips?

[C]

Yeah, so I have a bunch of tips in my book, but here's one that changed my life. Quit carrying your phone around your house.

[B]

But it's an appendage. What would we do without it?

[C]

Yeah, so try it. When you come home, put your phone in a drawer near the door and leave it there. If you want to use it, go to the drawer, use it, and put it back. I guarantee you it'll change your life.

[B]

Michaeling duclef thank you so much for sharing these fascinating insights into our phones and how we can, I don't know, get a bit of distance from them.

[C]

Oh, thank you so much, Emily.

[B]

If you like this episode, please share it with a friend. It really helps out Short Wave. Oh, and while you're at it, subscribe. This episode was produced by Hannah Chin. It was edited by Rebecca Ramirez. Tyler Jones checked the facts. Jimmy Keeley was the audio engineer. I'm Emily Kwong. Thank you for listening to Short Wave, the science podcast from npr.

[E]

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