You carry a slot machine in your pocket

Infinite scroll copies the mechanics of a slot machine: the variable reward. Sometimes the next piece of content is gold, almost always it's filler, and that uncertainty is exactly what hooks you.

Dopamine isn't the molecule of pleasure, but of anticipation. Experiments by the neuroscientist Wolfram Schultz showed that dopamine neurons fire harder for uncertain rewards than for guaranteed ones. B. F. Skinner had already observed it with his pigeons: intermittent reinforcement creates the behavior that's hardest to extinguish.

The feed knows this, which is why it never ends: with no ending, there's no stop signal. The antidote is friction: apps off the home screen, a grayscale display, the phone in another room. Against one design, another design.

Source: research by Wolfram Schultz, University of Cambridge