When you leave, the clock stops. So the app has a way to restart it. Your phone buzzes: a friend posted, someone liked your comment, a streak is about to end. Each buzz is a small door back in. The app does not send them by accident. It sends the ones that get people to open it.
'Your friend replied', opened60 in every 100 sent
'New videos you might like', opened15 in every 100 sent
Made-up rates, real shape.
Some buzzes are about you: a reply, a message. Some only look like they are: 'someone you may know joined', 'three new videos you might like'. The app tests both kinds. It keeps the ones that bring the most people back, and drops the ones people ignore.
Buzz'someone you may know joined'
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Why?
Why does the app send a buzz saying 'someone you may know joined'?
Because the law requires it.
Not yet. No law asks an app to tell you about strangers joining. What asks for it is the count of people who open the app after it.
Because it is important news for you.
Not yet. Someone you may know joining changes nothing for you today. It is sent because it works, not because it matters.
Because in tests, it brought people back.
Right. Every kind of buzz is tried on some users first. The ones that bring people back are kept. This one survived its test, so it gets sent.
3 of 10
Of ten buzzes, about three are from a friend.
Made-up split.
The buzz works because you cannot tell which one matters until you look. Sometimes it is a friend, sometimes nothing. Not knowing is what makes you look. A slot machine works the same way: it pays out sometimes, never on a pattern. Psychologists call this a variable reward, a prize that comes only sometimes.
Move the control to set how many buzzes the app sends you a day. The rule is made up: you open the app four times on your own, and six in ten buzzes bring you back once more.
Opens you started yourself4 opens a day
Opens a buzz started0 opens a day
0 buzzes a dayNo buzzes: about 4 opens a day, all of them yours.
Opens you started yourself4 opens a day
Opens a buzz started1 open a day
2 buzzes a day2 buzzes a day: about 5 opens, 1 of them started by a buzz.
Opens you started yourself4 opens a day
Opens a buzz started3 opens a day
5 buzzes a day5 buzzes a day: about 7 opens, 3 of them started by a buzz.
Opens you started yourself4 opens a day
Opens a buzz started6 opens a day
10 buzzes a day10 buzzes a day: about 10 opens, 6 of them started by a buzz.
Opens you started yourself4 opens a day
Opens a buzz started12 opens a day
20 buzzes a day20 buzzes a day: about 16 opens, 12 of them started by a buzz.
At 20 buzzes a day, which is bigger: opens you started, or opens a buzz started?
The buzz ones, three to one.
Right. Twelve opens from buzzes against four of your own. At that rate most of a day's sessions began with the app, not with you.
Your own. Nobody opens an app just because it buzzed.
Not yet. Six in ten do, in this rule, and something like that rate is why buzzes exist. If nobody opened after a buzz, the buzz would have failed its test and been dropped.
Equal. Buzzes only replace opens you would have made anyway.
Not yet. Some do. But the four own opens stay at four in every frame, while the buzz opens climb. The buzz adds sessions on top; it does not swap them.
Move the control.
Day 1 to day 99the number grows
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Day 100 missedit goes to zero
The streak is a buzz that lives inside the app. Message a friend every day and a number counts up. Miss one day and it goes to zero. Nothing real is lost. But the number was built so that losing it feels like losing something, and that feeling is a reason to open the app today.
In a 2023 study that logged American teenagers' phones for a week, how many notifications did the middle teenager get in a day?
Pick one. Nothing is scored.
237Notifications a day, middle teenager
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Of them, during schoolabout a quarter
About 240.Guesses run low because most buzzes are cleared without a thought. The study logged about 200 phones and found a middle value of 237 a day, some over 5,000, and about a quarter of them arriving during school hours.
Which of these is the app reaching out to you, and which is you reaching for the app?
One card at a time. Tap the pile it belongs to.
Card 1 of 6
A buzz: 'Your video has 3 new likes.'
You open the app to send a friend a photo.
A red badge with a number on the app's icon.
A streak that will end at midnight.
You search for a recipe you saw last week.
An email: 'You have unread messages.'
A buzz: 'Your video has 3 new likes.' → The app reaches out
Not yet. The app reaches out. You were not thinking about the video; the buzz put it in front of you, and that was its job.
You open the app to send a friend a photo. → You reach in
Not yet. You reach in. The thought came first, from you, and the app was the tool you picked up for it.
A red badge with a number on the app's icon. → The app reaches out
Not yet. The app reaches out. The badge was put there by the app, because tests show a number on an icon brings people back.
A streak that will end at midnight. → The app reaches out
Not yet. The app reaches out. The streak is the app's number, built to make a day without opening feel like a loss.
You search for a recipe you saw last week. → You reach in
Not yet. You reach in. Wanting the recipe came first; the app did nothing to prompt it.
An email: 'You have unread messages.' → The app reaches out
Not yet. The app reaches out. An email about messages is a buzz sent by another road, and it was sent because it works.
The app reaches outit started it
vsvs
You reach inyou started it
Right. The line is who started it. If the app put something in front of you before you thought of it, the app reached out. If the thought came first, you reached in. On most phones the first list is longer.
The game
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7pm buzz'Your crops are ready'
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You open it
A farming game sends a buzz at 7pm every evening: 'Your crops are ready.' The crops are not real. Why 7pm?
It is random and just happens to be 7pm.
Not yet. A buzz sent to millions at the same minute is not chance. It is a schedule, and the schedule was picked by whatever brought the most people back.
Because crops grow in the evening.
Not yet. The crops are numbers in a database. They are 'ready' whenever the game says. The time was chosen for the people, not the crops.
Tests showed 7pm brings the most people back, so that is when it is sent.
Right. Every part of a buzz can be tested: the words, the time, the sound. The 7pm buzz beat the 6pm and 8pm ones on opens, so 7pm is what everyone gets.
Lesson complete
A buzz is the app reaching out to restart the clock, sent because a test showed it works.