195 capitals
and one forgotten city

There are some things you learn and assume you'll simply carry for the rest of your life. For me, one of those things was the capital of every country in the world.

It started as a small obsession. I had a printed list of all 195 countries, grouped by continent, and I worked through it one region at a time: Africa, then Asia, then Europe, the Americas and Oceania. I tested myself in the evenings, then at breakfast, then in the gaps between everything else. After a few weeks I could go from Afghanistan to Zimbabwe without a single mistake. Kabul to Harare. I was proud of it in the way you're proud of something nobody asked you to do.

I didn't look at the list again. Why would I? I knew it.

The quiz night

A few months later, someone at a quiz night asked for the capital of Burkina Faso. I knew that I knew it. I could almost see the word on my old printed list: long, full of vowels, somewhere near the top of the Africa column. But it wasn't there. Someone else said Ouagadougou and I felt something close to embarrassment. Not because I'd forgotten one capital, but because I suddenly wasn't sure how many others I'd forgotten too.

So I tested myself that night. It was humbling.

It wasn't just capitals. When I looked honestly, the same thing had happened everywhere: vocabulary I'd been proud of, ideas from books that had changed how I thought, formulas, a handful of quotes I'd promised myself I would live by. I had learned them properly. And then, without noticing, I had let them go.

Reading about forgetting

I wanted to know whether this was a me problem. It isn't. In the 1880s Hermann Ebbinghaus spent years memorising lists of nonsense syllables and measuring how quickly they disappeared. He plotted what we now call the forgetting curve: a steep drop in the first days after learning, then a long, low tail. My capitals had followed that curve exactly. I had learned them once, never reviewed them, and let biology do the rest.

The more hopeful half of the research is the spacing effect. If you actively recall something just as it's starting to fade, the memory comes back stronger and the next drop is slower. Do that a few times, with the gaps growing each time, and the curve flattens out almost completely. It's one of the most consistently replicated results in the psychology of learning, and almost nobody uses it on purpose.

I tried the existing tools. Some were powerful but felt like a second job: hundreds of flashcards a day, settings I didn't understand, a queue that punished me for missing a weekend. What I wanted was much simpler. I wanted to say “this matters, don't let me lose it”, and have something tap me on the shoulder at exactly the right moments for the next year.

Six taps on the shoulder

So I built that. Every topic you add to Spaced gets a roadmap of six reviews: on day 3, 7, 15, 30, 90 and 365. Early reviews come quickly, because that's when a new memory is most fragile. Later ones are months apart, because by then the memory can hold on by itself. Each review only unlocks on its due date. Recalling something early feels productive but does much less, so Spaced won't let you cheat.

The first roadmap I ever created was, of course, Countries Capitals. It's still the first set in the Spaced catalog, right next to 500 advanced English words, world currencies, official languages, logical fallacies, cognitive biases, the pillars of Stoicism and the founders and holy books of the world's major religions. They're all things I wanted to keep for life.

It has been well over a year now, and every one of those six reviews has come and gone. Ask me the capital of Burkina Faso. I won't even hesitate.