There are few more depressing scenes than the one painted by the anthropologist Natasha Dow Schüll in her book Addiction by Design. She describes slot-machine players in Las Vegas so absorbed in their gambling that, when one of them collapses after suffering a cardiac arrest at the slots, others neither notice nor make space for the paramedics.

As Schüll explains, these slot-machine superusers aren’t even playing in the hope of winning money, but because they find the machine soothingly absorbing. They have entered what we might call the “junk flow state” — a grotesque parody of what the psychologist Mihaly Csikszentmihalyi called “flow”, a state of intense focus and immersion in a challenging activity.

Disheartening stuff. But even more disheartening is the knowledge that the same techniques long ago escaped the casinos and settled on your smartphone. Now toddlers watch TikTok with the same slack-jawed expression as the slot-machine addicts, while couples interrupt their dates to show some love to their phones.