How Flashcards Fail: Confessions of a Tired Memory Guy

You can use flashcards and spaced repetition to memorize almost anything – so why did I come to hate my reviews? Explore the dark side of this amazing memory system.

[UPDATE: You all left so many amazing comments on this article with awesome solutions! So I’ve compiled my favorite solutions into a whole separate article, “How Flashcards Succeed.” I’ll link to it at the end – don’t miss it!]

In my last post, I shared how spaced repetition flashcards made my memory feel like a superpower. I learned to remember thousands of things that would otherwise have misted away.

How Did I Come to Hate Reviews?

But flashcards depend on daily reviews. And after a few years, I just couldn’t stand the reviews anymore. I started skipping days. Weeks. Months. Today, if I fire up Anki, I have over 2000 cards due.

What went wrong?

At first, I blamed myself. I lacked stamina. Determination. Something.

But the solution isn’t that simple. On reflection, I’ve realized that flashcards and spaced repetition have some inherent dangers and difficulties. We can work around them, but only if we step back and think about them.

Review Clusters and Adding New Cards

The first problem: spaced repetition is uneven. That’s the nature of the math. Some days will have only a few reviews. Others will have a ton of cards. Those huge days can be demoralizing. You fire up Anki, and you have hundreds of reviews.

There are several ways to deal with this.

At a minimum, if you have a ton of cards due, don’t add any new cards that day.

You can also break up your reviews into several short sessions. But I rarely did that. I wanted to get reviews done (more on that later).

Also, Anki has a feature where you can see which days coming up will be big days. If you know tomorrow’s going to be a big day, you could review some of those cards today, ahead of time.

But there’s a deeper problem: depending on how you add new cards today, you could be creating mammoth review days down the road. That math is just too complex for a normal person to do on the fly. I want to know: if I add 20 cards today, are they going to land on some day next week that’s already huge?

This seems like a problem the program could address. It can’t predict exactly how much you’ll need to review. But perhaps it could estimate, and warn you if new cards today will land on a day next week that’s already overbooked.

Boredom Bias

A much more difficult problem is the boredom bias. The more boring a card is for you, (unless it’s boring because it’s easy), the more likely you are to get it wrong.

But the whole point of spaced repetition is to focus your time on the cards you get wrong!

Pretty soon, you’re spending most of your review time precisely on the most boring and/or difficult cards.

Damien Elmes, the lead Anki developer, is aware of this problem. His “leech” feature will remove a card after you miss it a whole bunch of times. But when you have thousands of cards, it can take a long time to purge each leech.

Card Laziness

Of course, you can set leeches to disappear faster. But is that the answer? You don’t want to disappear a leech. You want to figure out how to learn it. Isn’t that why it’s in your deck?

Either it’s important, and you need to fix it, or it’s not important, and it’s been a waste of time from the start.

But fixing leeches is a pain. It’s especially a pain if you’re reviewing with AnkiDroid, or another mobile app.

Yes, Anki on your phone is tantalizing. You can slip life-changing memory building into the dribs and drabs of time that are otherwise “wasted”.

But when you trip up on a leech, the last thing you want to do is wrestle with your tiny onscreen keyboard.

Even if you have a usable mobile keyboard, fixing a leech feels like breaking the flow. I’m trying to review here. Get this done. I don’t want to slow down and … um … think?


Flashcards As Tests

At last we poke the raw nerve. What exactly am I doing when I review flashcards? What’s the “flow” that I don’t want to break by fixing broken flashcards?

Am I taking a test?

I’ve spent about half my life (at this point) in school. School is about tests.

When I started doing flashcards, I was excited about how different they are from tests. Tests are a single snapshot of your recall at a particular time. Unfortunately, most students, including valedictorians, forget almost everything they ever get tested on. Traditional tests are a complete failure.

Flashcards are different, because you maintain knowledge. Spaced repetition ensures that you keep seeing things before you forget them.

But flashcards still feel a lot like school tests. Yes, in theory, it doesn’t matter much whether I get a card wrong, since I’ll see it tomorrow. But in practice, I hated getting cards wrong.

At first, I thought this dislike was an old school hangup. I expected that, in time, I would adjust to this awesome new world of gradeless reviews.

But the opposite happened. As time went on, my hatred for mistakes grew.

Spaced Repetition Collects Your Worst Cards

And because of the “boredom bias”, I was spending more and more time reviewing my least favorite cards, getting them wrong, and knowing I would have to see them again.

I began to amass a mental collection of cards that I could remember missing. The card would come up, and I’d think, “I always miss this.” And I would.

That is amazing. Think about that. Whatever I was doing, it was training my brain to remember that I couldn’t remember this. Somehow, I had spent enough time to make that connection, instead of connecting to the actual fact.

Why? Because I was mostly thinking about whether I’d get it right, not about what I was trying to learn.

Flashcards As Video Game

Flashcard review has an intense gravitational pull towards focusing on the actual flashcards:

  • How many cards you’ve gotten wrong.
  • How many cards are left.
  • How long it’ll take to finish them, so you can get back to your real life.

As a friend put it, flashcards feel like a video game. Wow! They really do. And I like video games, but they’re fundamentally geared towards success. Points. Levels. Defeating obstacles.

Should memorizing be a video game?

No. Flashcards are a huge step forward from tests, but if you’re focusing on success, you’re still fundamentally focused on grades. And that leads to absurdities like, in my case, actually memorizing that you always miss a question.

It also leads to the flashcard flow. I wanted to get through these cards as fast as possible! The last thing I wanted to do is hit the brakes and reformulate some broken card. That felt like losing.

Atomizing and Randomizing Knowledge

Flashcards seemed to disconnect me from the actual knowledge. Instead of immersing myself in the knowledge, I found myself controlling a flashcard slot machine.

The knowledge was atomized and randomized. I’d get a Spanish word, then some obscure fact from Edible Forest Gardens, then a letter in Morse Code.

This randomization is essential to spaced repetition. I needed to see that Spanish word, on that day.

For vocabulary, this might have been fine. Words are tiny bits of information that need to be random. We want to be able to reach for any word at any time.

It’s interesting that both SuperMemo and Anki were developed by programmers who were trying to learn a language. Despite all my problems with flashcards, I still think they could be an essential tool for mastering large quantities of vocabulary.

But what about the facts from books? Does it really help that a particular fact is only associated with the question on one flashcard? Is that really how our minds work?

Flashcards Kill Clustering

No. Our minds use chunks and clusters. You want more connections to each fact, not less.

Flashcards work directly against this mental need. Flashcards atomize each fact completely out of any context, except its context as a random flashcard.

Think about your friends, or even acquaintances. You think of a name, and instantly you get a face, hair color, voice, an outfit, the rooms where you see this person – and that’s all in less than a second. If you focus, you can pull tens, hundreds, probably thousands of discrete facts that cluster around this single person.

Spaced repetition and flashcards kill clustering. Instead of associating multiple facts from the same book with one another, you split them all up. Divide and forget.

For me, almost all this knowledge began to have no other meaning than as a flashcard. The only time I thought about it was when I was testing myself.


In short, this tool for remembering more of reality had morphed into an oppressive, self-contained computer game. The only way to win was to finish as fast as possible.

How can I fix this?

By questioning my underlying assumptions about the whole method.

Next time: Reviewing as Thinking

[UPDATE: As promised, here’s the followup article with an epic list of Anki solutions: How Flashcards Succeed.]