What makes someone keep scrolling or watching, day after day? Some of the same design elements that made video slot machines so compulsive have quietly migrated into social media, games and streaming apps — and they’re especially dangerous for children.
In two recent landmark cases, social media companies were found liable for harming children; Meta and Google are appealing and deny that their products are addictive. Still, more than a decade of research has identified core design features that apps use to hold attention and monetize it. Cultural anthropologist Natasha Dow Schüll, who spent 15 years studying video slot machines, says these features act like “superglue,” keeping people on apps longer and costing them time, energy and sometimes money. Understanding them gives parents a way to judge how harmful an app may be.
Schüll’s work began in casinos. In the 1980s and ’90s, the gambling industry intentionally developed video slot machines — large, screen-centered devices you can play for hours — that produced what researchers call a “machine zone” or “dark flow,” a trancelike dissociation where players lose track of time and surroundings. Some gamblers played for 24–48 hours straight; some even avoided bathroom breaks to stay in the game.
From interviews with players, engineers, marketers and executives, Schüll distilled four interacting features that make these machines so absorbing. Around the 2010s, those same features started appearing on phones and tablets. The four are:
1) Solitude
When interaction is strictly between you and the device, social cues that normally signal it’s time to stop disappear. Apps encourage private, isolated use — think kids alone in their bedrooms — which research links to higher risk of problematic usage: continuing to use an app despite negative consequences for sleep, relationships or health.
2) Bottomlessness
Content is effectively endless. Infinite scroll, autoplay videos and feeds that continually refill remove natural stopping points. Without a sense of completion, users never feel satisfied and keep chasing “one more” item.
3) Speed
Faster cycles of action and feedback increase time spent. Schüll found that faster play on slot machines led to longer sessions; the same applies to taps, swipes and autoplay on apps. High-speed delivery makes it easier to slip into flow, blurring where you end and the machine begins.
4) Teasing — being given almost what you want
This is perhaps the most potent. Apps use AI to predict what you seek and then withhold the exact reward, instead offering something close enough to keep you engaged. Over time you chase increasingly targeted content, convinced the next item will be the one you were after. Neuroscientist Jonathan D. Morrow explains that this “teasing” creates persistent possibility — a reason to stay longer in hope of finally getting the desired payoff.
Combined, these features form a recipe for overuse. Solitude removes social checks; bottomlessness removes endpoints; speed accelerates immersion; teasing keeps desire active. Schüll asks students to rate apps by these criteria to gauge harm, and both she and Morrow stress children are especially vulnerable. Kids’ developing brains, weaker impulse control, and time spent unsupervised make them more likely to be trapped by this design cocktail.
The comparison to casinos is not metaphorical: many design techniques were refined in gambling and then adapted for attention economies. Technological advances — faster internet, sophisticated recommendation algorithms, and interface patterns like infinite scroll — amplified the impact. The result is products that create relationships with users rather than serve as simple tools or toys.
That reality has policy implications. While parents can help by limiting unsupervised access, setting boundaries and discussing habits with children, experts argue designers should be held accountable and products regulated to protect young users from manipulative features.
Michaeleen Doucleff has a Ph.D. in chemistry and is a longtime science journalist (including previously for NPR). She is the author of the parenting book Dopamine Kids.