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

Episode Date: June 1, 2026

You pick up your phone to do one quick task, and suddenly 20 minutes have flown by without you even noticing. How do apps do that to you? Science journalist Michaeleen Doucleff felt like her phone had superglue on it, holding her on it for hours each day while draining her of time and energy. Turns out, that feeling isn’t accidental. In her new book, Dopamine Kids, Michaeleen describes four features that tech companies add to apps to keep us scrolling for as long as possible. She’s sharing this superglue recipe with Short Wave host Emily Kwong … and explaining how these features can pull people into what scientists call a ‘dark flow’ state.Interested in more tech and social media science? Email us your question at [e-mail] to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.Listen to Short Wave on Spotify and Apple Podcasts.This episode was produced by Hannah Chinn. It was edited by Rebecca Ramirez. Tyler Jones checked the facts. The audio engineer was Jimmy Keeley.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hi, shortwavers. Emily Kwong here with NPR alum, now independent science journalist, Mike Lean, Do Clef. Hi, Emily. I hear you have a new book out now about the science behind screen time. 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. It's awful. Yeah, I pick up my phone to do one thing. suddenly I'm on social media for 20 minutes. I don't know how that happens. 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. And this 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 YouTube deliberately design their apps. to be addictive for kids. 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 Dalshaw puts it. Things that keep us, you know, spending more time, spending more money, draining more of us and our energy and our cells, what might literally prevent flourishing. Yes, this is what social media addiction and, like, obsession sounds like.

But these features, they have a surprising history right here. Yes, they have deep roots in the gambling industry. So today on the show, we are digging into the design of your favorite phone app and learning how tech companies mimicked the gambling industry to keep us scrolling and staring. I'm Emily Kwong. I'm Mike Lean Doe Club. and you're listening to Shortwave, the science podcast from NPR. Okay, Michaeline, so this story begins in the casinos of Las Vegas.

Take us back in time and explain what was happening there. 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. Oh, how did they do that? So they went around and ripped up nearly all the money. mechanical slot machines in 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. 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. It's like they were apps before they were apps. The gambling games just played on screens. That's right. They're like apps with giant touch screens 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. Wait, who gave the user feedback?

The gamblers. The casinos essentially ran these large-scale experiments on all the millions of people, gambling each year in Vegas. They tweak the device a bit and then see if those changes increase the time people spend gambling. Then they just repeated the process for decades. So they were performing essentially massive A-B testing on gamblers. 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. Like they don't even stop to use the bathroom? Sometimes not. That anthropologist we just heard from, Natasha Dalshaw, 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.

That's awful. That makes me so sad to hear because it just shows the power these devices have on people's attention. 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, game. aims in the same way. 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. Michael, let's blow the cover off of this. What are the four ingredients in social media superloo? Okay. So the first ingredient is solitude. You use the app alone. It's just you and the screen. This is important because it removes social cues for stopping. 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.

So you're saying it's the presence of other people that helps pull us out of that machine zone state. 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. I've experienced this as an adult. Okay, what is the second ingredient? social media super gloom. 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. There's no natural stopping point. So as you're scrolling,

you may have a little thought in your head like, hmm, maybe I should go to sleep, right? But then another outrageous video pops up in your feed. I genuinely feel like I'm being baited, like a fish. And that I'd 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. Exactly. And that feeling grows even stronger when you add in the third ingredient. Which is speed. Ah, right. 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 1,200 games per hour or like one game every three seconds, it's bonkers. 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. 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, there was a huge jump in use. know why that's the case that moving faster would make us stay on the app longer? Yeah, you know, scientists don't know yet, but Natasha suspects... The speed can cause this sense where you feel like you're kind of don't have a sense of

where you begin and the machine ends and it really just pulls you into this flow. I don't like that. I don't want to be hooked up to a machine. Yeah, I mean, Natasha says you can have this feeling that you sort of merge with the screen. I don't like it. Me neither. So, Emily, can you guess what you? what the fourth ingredient is? I'll give you a hint. A.I.

is really good at it. Oh, you mean the algorithm. Yes, the fourth ingredient is a personalized algorithm and how it selects content for you. Yes, it does. 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. They know what you want. They're very good at figuring that out. But then this is key. They don't give it to you. They give you something close to that. Then a few clicks later, the algorithm gives you something even closer.

Giving you what you want to get you off the app. They don't want that. 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. Exactly. So they sort of tease you in a way, right? Yeah, they're not trying to satisfy you.

The app makes you feel like you're making progress or getting closer to your goal. Mateo Shkola is a neuroscientist at UCC and Diego. He says when people feel like they're making progress, progress, they double down their effort and try harder. 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. Because in the real life, when we try again, this dopamine really motivates us to get closer, closer, closer, and hit it.

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. Yeah. There's always this possibility, right, of getting what you want. So the social media super glue recipe is as follows. Solitude, bottomlessness, speed, and teasing. 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. 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? Yeah. So that's the like classic flow state, you know, the one that the psychologist, Miha, Chick-Sit-Mehi described back in the 80s,

people go into these good flow states when they're doing complex and challenging task 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. Yeah, you get a little mood bump. 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? Lothargic and maybe even gloomy. 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?

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. How'd you do that? 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? Wow. Yeah, we cut back on our movie watching. I'd say like a tenth. You never binge when you have to pay for it each time. Yeah.

These are great. Any other tips? 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. But it's an appendage. What we do without it? 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. My clean Duke-Clough, 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. Oh, thank you so much, Emily. If you like this episode, please share it with a friend. It really helps out. Shortwave.

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 Keely was the audio engineer. I'm Emily Kwong. Thank you for listening to Shortwave, the science podcast from NPR.