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Chapter 12 of the book

Attention in the Age of the Phone

ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.3 things to start with2 popular claims graded28 works cited

How the chapter opens

In 2025 researchers reported a trial in which Turkish high-school students did their math practice with an AI beside them. The question was plain: does help from a machine turn into learning, or only into better homework?

The students were split three ways. One group got a large language model, the kind of AI that writes fluent answers to typed questions, with no restrictions: ask for the solution and get it. A second group got the same model with guardrails: it would not hand over the answer, only nudge the student toward the next step. The third group worked the way students always had, with no AI at all.

What the chapter covers

The argument, the studies and the stories are in the book. Get the book.

  • ·What Your Body Expects
  • ·Designed to Be Checked
  • ·Handing Over the Thinking
  • ·Children, Play and the First Phone

Mismatch card

The system

The reward circuit that learns from unpredictable payouts; the default network that runs during idle time; memory, navigation and reasoning that improve with use; and a child's play-driven development.

What it expects

Rewards that are earned, spaced and often absent; long stretches with nothing to attend to; problems solved with your own equipment; and childhood days of free, mixed-age, outdoor play.

What it gets

A pocket device engineered for time on device, paying out on a variable schedule and filling every gap; tools that supply the answer before the effort starts; and childhoods with hours of screens and the risk designed out.

What happens in the gap

Checking that resists unlearning, idle minutes that vanish, work that looks better while the person doing it learns less, and afternoons a phone ban empties but does not refill.

The handrail

The phone out of the bedroom, notifications from people only, AI as a spotter, phone-free times, free outdoor play for children (ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.)

Strength of evidence

ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials. One large randomized trial on adult social media and one strong field trial on AI and learning, set against a genuinely open argument about teenagers and a thin, mostly observational literature on play.

What you've heard

Popular claims this chapter tests, each with the book's verdict and grade.

The protocol

Each action carries the book's evidence grade. How the grades work.

Start here

  1. Charge the phone outside the bedroom

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.for children and teensEmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.for adults

    How: a charger in the kitchen or hall and a cheap alarm clock by the bed. Why: an expert panel agreed that screen use before bed harms sleep in children and teens, where the evidence is firmest; among young adults, more screen time in bed goes with more insomnia and less sleep (Chapter 8).18

  2. Turn off every notification that is not a person

    EmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.

    How: in settings, leave on calls and messages from people; switch off news, shopping, games, likes and "you might have missed". Why: every alert is one more unpredictable payout on the slot-machine schedule. No trial has tested this on its own, but the cost of trying is a few minutes.

  3. Use AI like a spotter, not a stand-in, whenever you want to learn or keep a skill

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    How: ask for a hint, a question or a check of your own attempt before any finished answer; if the tool allows it, tell it to tutor rather than solve. Why: in the Turkish trial, the version that withheld answers gave the biggest gains and no exam penalty, while full answers cost students on the exam. If the only goal is the output, this does not apply.

Then, pick from this menu

  • **Make some times and places phone-free (EmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.).** Meals, the first and last hour of the day, and above all the conversations that matter: put the phone in another room. In two small experiments, a phone merely lying on a nearby desk made conversations feel less close.19 Keep a phone reachable for real emergencies.

  • **Take a planned break of a few weeks from the app that bothers you most (ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.).** Delete it from the phone so willpower is not doing the work; the best trial used four weeks. Expect a small lift and a lasting drop in use, not a transformation.

  • **When boredom arrives, let it sit for a few minutes before you reach for the phone (EmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.).** In the queue, the waiting room or the first ten minutes of the commute. The mind's inward work seems to run in these gaps, but no trial shows that leaving them empty improves anything measurable.

  • **Do the first pass yourself (EmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.).** Draft the email, the plan or the essay badly on your own, then ask the AI to improve it. Try the recall before the search, and take a familiar route without the map now and then. Small studies and a plausible mechanism support this, not trials.

  • **Give children free, outdoor play with some real risk in it (EmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.).** Play the child starts, runs and ends, with adults nearby but out of the referee's job. Graded means a challenge the child chooses, never open water or traffic. Why: children with more freedom are more active, though the evidence is mostly low quality. About two hours outdoors a day also protects young eyes (Chapter 7).

  • **Give independence before the phone (EmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.).** Errands, walking routes and time out of sight, sized to the child. Why: in the risky-play review, freedom to roam went with more activity.

  • **Back a school phone ban, then fill the afternoon it cannot fill (EmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.).** Why: bans cut phone use during the school day, but in the one large study well-being did not change.

If this is you

Anxious, or checking feels compulsive

start with notifications and the bedroom, then try a break of a few weeks from one app. If checking or low mood is taking over your days, talk to a clinician (Chapter 13).

Waking in the night, including the 3 a.m. waking common in perimenopause

a phone in the kitchen cannot be picked up at 3 a.m. See Chapter 8 for what to do instead and Chapter 15 for why it happens.

Over 50, or living alone

keep every notification from people switched on, since those are the ones that connect you (Chapter 11). Do the first pass yourself on things you want to keep: routes, sums, names. Cognitive reserve is well supported, though no dose is known; Chapter 16 lists the dementia risks you can change.

Parents

set the house rules before the first phone arrives, including where devices sleep. Protect unstructured outdoor time, which a school ban does not supply. Expect no age that is right for every child.

Short on time

the first two actions take about ten minutes, once, and then run themselves.

Night shifts

the bedroom rule covers your daytime sleep too.

Tight budget

everything here is free. The one purchase worth making is an alarm clock.

If you use AI or other tools to read, write, speak or manage a diagnosed condition

the spotter rule does not apply to that use. There the tool is a ramp, not a stand-in.

Safety

Keep a phone within reach for emergencies, especially if you care for someone or live alone. If phone use, gaming or betting feels out of control, or comes with persistent low mood or anxiety, see a clinician; effective treatments exist (Chapters 13 and 14). Nothing in this chapter argues against treatment for depression, anxiety or ADHD. Risky play means graded risk with an adult nearby; traffic, open water and firearms are hazards, and the ordinary precautions apply.

The skeptic's box

What could overturn this chapter, from the chapter itself.

Almost everything in this chapter is weaker than its headlines. The best adult trial is one study of paid Facebook users in 2018, before short-video apps took over; its effect is small, and it says nothing direct about teenagers. The Turkish trial is strong but covers one subject in one country, and it measured learning, not brain health; no study yet shows that AI use harms a healthy adult brain. The risky-play reviewers graded their own evidence very low quality. The school phone study is a single snapshot that cannot separate cause from selection. On teenagers, the timing and the pattern favor the alarm, the direct searches for large effects favor the skeptics, and reverse causation fits the long-term data about as well as harm does. What would settle it: trials that randomly assign whole schools or families to reduced use and follow the children for years. And the alarm itself is old. In Plato's Phaedrus, Socrates warns that writing will breed forgetfulness, because people will trust outside marks instead of their memory. He was right about the mechanism, and nobody proposes giving up writing.20

Go deeper in the reference library

The research this chapter was built from, as longer reference entries: each with its own mismatch card, graded recommendations and the case against it.

See also in the book

Sources behind this page

  1. 20.Plato. Phaedrus, approximately 274c-275b (Stephanus pagination). Paraphrased; no translation is quoted.
  2. 8.Radtke, T., Apel, T., Schenkel, K., Keller, J., and von Lindern, E. (2022). "Digital detox: an effective solution in the smartphone era? A systematic literature review." Mobile Media & Communication, 10(2), 190-215. https://doi.org/10.1177/20501579211028647 ; Liu, Y., Mohamad, E.M.W., Azlan, A.A., and Tan, Y. (2025). "Am I happier without you? Social media detox and well-being: a meta-analysis of randomized controlled trials." Behavioral Sciences, 15(3), 290. https://doi.org/10.3390/bs15030290 ; Calvert, E., Cipriani, M., Dwyer, B., Lisowski, V., et al. (2025). "Social media detox and youth mental health." JAMA Network Open, 8(11), e2545245. https://doi.org/10.1001/jamanetworkopen.2025.45245 (The systematic review covered 21 studies; the 2025 detox study was an uncontrolled cohort.)
  3. 16.Odgers, C.L. (2024). "The great rewiring: is social media really behind an epidemic of teenage mental illness?" Nature, 628(8006), 29-30. https://doi.org/10.1038/d41586-024-00902-2 ; Twenge, J.M., Martin, G.N., and Campbell, W.K. (2018). "Decreases in psychological well-being among American adolescents after 2012 and links to screen time during the rise of smartphone technology." Emotion, 18(6), 765-780. (Twenge's analysis reports a cross-sectional dose-response link.)
  4. 17.Orben, A., and Przybylski, A.K. (2019). "The association between adolescent well-being and digital technology use." Nature Human Behaviour, 3(2), 173-182. https://doi.org/10.1038/s41562-018-0506-1 ; Vuorre, M., Orben, A., and Przybylski, A.K. (2021). "There is no evidence that associations between adolescents' digital technology engagement and mental health problems have increased." Clinical Psychological Science, 9(5), 823-835. https://doi.org/10.1177/2167702621994549 (Orben and Przybylski analyzed 355,358 adolescents across three datasets.)
  5. 18.Hartstein, L.E., Mathew, G.M., Reichenberger, D.A., Rodriguez, I., et al. (2024). "The impact of screen use on sleep health across the lifespan: A National Sleep Foundation consensus statement." Sleep Health, 10(4), 373-384. https://doi.org/10.1016/j.sleh.2024.05.001 ; Hjetland, G.J., Skogen, J.C., Hysing, M., Gradisar, M., and Sivertsen, B. (2025). "How and when screens are used: comparing different screen activities and sleep in Norwegian university students." Frontiers in Psychiatry, 16, 1548273. https://doi.org/10.3389/fpsyt.2025.1548273 (The panel did not agree that screen light itself harms sleep; the student survey was cross-sectional.)
  6. 19.Przybylski, A.K., and Weinstein, N. (2013). "Can you connect with me now? How the presence of mobile communication technology influences face-to-face conversation quality." Journal of Social and Personal Relationships, 30(3), 237-246. https://doi.org/10.1177/0265407512453827 (Published online 2012; effects were clearest when the topic was personally meaningful.)

Every work this chapter cites

The chapter's 20 notes cite 28 works, listed by note number. Each is also in the full source register.

  1. 1.Bastani, H., Bastani, O., Sungu, A., Ge, H., et al (2025). Generative AI without guardrails can harm learning: Evidence from high school mathematics. Proceedings of the National Academy of Sciences. 10.1073/pnas.2422633122
  2. 2.Raichle, M.E., MacLeod, A.M., Snyder, A.Z., Powers, W.J., et al (2001). A default mode of brain function. PNAS. 10.1073/pnas.98.2.676Buckner, R.L., Andrews-Hanna, J.R., and Schacter, D.L (2008). The brain's default network: anatomy, function, and relevance to disease. Annals of the New York Academy of Sciences. 10.1196/annals.1440.011
  3. 3.Wilson, T.D., Reinhard, D.A., Westgate, E.C., Gilbert, D.T., et al (2014). Just think: the challenges of the disengaged mind. Science. 10.1126/science.1250830for published pushback, see "Is thinking really aversive? A commentary on Wilson et al." Frontiers in Psychology (2014). , and "Motivations underlying self-infliction of pain during thinking for pleasure.
  4. 4.Stern, Y (2012). Cognitive reserve in ageing and Alzheimer's disease. The Lancet Neurology. 10.1016/S1474-4422(12
  5. 5.Schüll, N.D (2012). Addiction by Design: Machine Gambling in Las Vegas.
  6. 6.Allen, M (2017). Sean Parker unloads on Facebook: 'God only knows what it's doing to our children's brains.'. Axios. axios.com
  7. 7.Allcott, H., Braghieri, L., Eichmeyer, S., and Gentzkow, M (2020). The welfare effects of social media. American Economic Review. 10.1257/aer.20190658
  8. 8.Radtke, T., Apel, T., Schenkel, K., Keller, J., and von Lindern, E (2022). Digital detox: an effective solution in the smartphone era? A systematic literature review. Mobile Media & Communication. 10.1177/20501579211028647Liu, Y., Mohamad, E.M.W., Azlan, A.A., and Tan, Y (2025). Am I happier without you? Social media detox and well-being: a meta-analysis of randomized controlled trials. Behavioral Sciences. 10.3390/bs15030290Calvert, E., Cipriani, M., Dwyer, B., Lisowski, V., et al (2025). Social media detox and youth mental health. JAMA Network Open. 10.1001/jamanetworkopen.2025.45245
  9. 9.Sparrow, B., Liu, J., and Wegner, D.M (2011). Google Effects on Memory: Cognitive Consequences of Having Information at Our Fingertips. Science. 10.1126/science.1207745
  10. 10.Dahmani, L., and Bohbot, V.D (2020). Habitual use of GPS negatively impacts spatial memory during self-guided navigation. Scientific Reports. 10.1038/s41598-020-62877-0Gerlich, M (2025). AI Tools in Society: Impacts on Cognitive Offloading and the Future of Critical Thinking. Societies. 10.3390/soc15010006Kosmyna, N. et al (2025). Your Brain on ChatGPT. arxiv.org
  11. 11.Konner, M (2017). Hunter-Gatherer Infancy and Childhood. Hunter-Gatherer Childhoods. 10.4324/9780203789445-3
  12. 12.Rideout, V., Peebles, A., Mann, S., and Robb, M.B (2022). The Common Sense Census: Media Use by Tweens and Teens, 2021.
  13. 13.Sandseter, E.B.H (2007). Categorising risky play: how can we identify risk-taking in children's play? European Early Childhood Education Research Journal. 10.1080/13502930701321733
  14. 14.Brussoni, M., Gibbons, R., Gray, C., Ishikawa, T., Sandseter, E.B.H., Bienenstock, A., et al (2015). What is the relationship between risky outdoor play and health in children? A systematic review. International Journal of Environmental Research and Public Health. 10.3390/ijerph120606423
  15. 15.Goodyear, V.A., Randhawa, A., Adab, P., Al-Janabi, H., Fenton, S., Jones, K., Michail, M., Morrison, B., Patterson, P., Quinlan, J., Sitch, A., Twardochleb, R., Wade, M., and Pallan, M (2025). School phone policies and their association with mental wellbeing, phone use, and social media use (SMART Schools): a cross-sectional observational study. Lancet Regional Health - Europe. 10.1016/j.lanepe.2025.101211
  16. 16.Odgers, C.L (2024). The great rewiring: is social media really behind an epidemic of teenage mental illness? Nature. 10.1038/d41586-024-00902-2Twenge, J.M., Martin, G.N., and Campbell, W.K (2018). Decreases in psychological well-being among American adolescents after 2012 and links to screen time during the rise of smartphone technology. Emotion.
  17. 17.Orben, A., and Przybylski, A.K (2019). The association between adolescent well-being and digital technology use. Nature Human Behaviour. 10.1038/s41562-018-0506-1Vuorre, M., Orben, A., and Przybylski, A.K (2021). There is no evidence that associations between adolescents' digital technology engagement and mental health problems have increased. Clinical Psychological Science. 10.1177/2167702621994549
  18. 18.Hartstein, L.E., Mathew, G.M., Reichenberger, D.A., Rodriguez, I., et al (2024). The impact of screen use on sleep health across the lifespan: A National Sleep Foundation consensus statement. Sleep Health. 10.1016/j.sleh.2024.05.001Hjetland, G.J., Skogen, J.C., Hysing, M., Gradisar, M., and Sivertsen, B (2025). How and when screens are used: comparing different screen activities and sleep in Norwegian university students. Frontiers in Psychiatry. 10.3389/fpsyt.2025.1548273
  19. 19.Przybylski, A.K., and Weinstein, N (2012). Can you connect with me now? How the presence of mobile communication technology influences face-to-face conversation quality. Journal of Social and Personal Relationships. 10.1177/0265407512453827

The full source register

This page carries the chapter's apparatus. The chapter itself, and the fifteen others, are in the book.

Get the bookThe 30-day protocolAll sixteen chapters