CHAPTER 8

8. Never Forget Again

In late 1878, a little-known German psychologist named Hermann Ebbinghaus set out to prove a wild and unfounded theory. Unlike his contemporaries, Ebbinghaus believed that higher mental processes, like memory, could be studied using scientific experimentation. Over the next seven years, he developed and refined a set of experiments, which he set about performing on himself and others.

Today, we would probably consider these experiments a form of psychological torture.

You see, Ebbinghaus knew, as you now do, that any prior knowledge would give an unfair advantage and skew his results. For this reason, he developed a list of 2,300 nonsense syllables, such as “daw,” “ked,” and “za.” Ebbinghaus would then memorize a random set of syllables by reading them aloud and attempting to recall them later on. As if this doesn’t sound mind-numbing enough, you should know that just one session of this experiment included fifteen thousand recitations.

By 1885, Ebbinghaus had made some groundbreaking discoveries in the fields of memory and learning. His first book, Über das Gedächtnis: Untersuchungen zur Experimentellen Psychologie (translated as Memory: A Contribution to Experimental Psychology), was a monumental success. Besides earning him a professorship at the University of Berlin, Memory sparked a renaissance in the psychological and scientific communities. Before Ebbinghaus’s work, little if any research was conducted on the science of memory. In 1894, however, shortly after the translation of Ebbinghaus’s research, thirty-two papers on the science of memory were published in the United States alone.

To this day, Ebbinghaus’s work has left lasting contributions to our understanding of memory. Most notably, Ebbinghaus discovered that our memory is subject to exponential loss. No, I’m not talking about you losing your keys exponentially more often as you age. Exponential loss means that there’s a sharp, nonlinear decline in memory immediately after learning something.

This probably doesn’t surprise you a whole lot. But here’s the more interesting (and useful) part. Ebbinghaus discovered that with repeated, spaced repetition, his memory of the random syllables became better and better. While it would take him only a day or so to forget a set of syllables the first time around, by the second time, he could hang on to it for twice as long. By the fourth or fifth time, it would stay in his memory for weeks. Eventually, his knowledge of this information would seem almost permanent.

Graphed visually, this gradually improving memory loss looks like this:

Ebbinghaus called this the forgetting curve—and it’s the basis for one of the most important fundamentals in accelerated learning: spaced repetition.

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In the last couple of chapters, you’ve learned the world’s most powerful ways to make things memorable. With these techniques, you will be able to remember things faster, with greater ease, and for longer durations. You’ll have a much easier time moving things from your short-term memory to your long-term memory.

But even with the world’s most proven mnemonic devices, they won’t stay there forever.

After all, you are fighting against millions upon millions of years of evolution.

Remember those two seahorses getting sucked into the vacuum? Every night, as you sleep peacefully, your hippocampi are hard at work, trying to figure out where they can “trim the fat” and get rid of unused memories. I’m sure they appreciate all the hard work you’ve done to keep things interesting for them, but ultimately, they have a job to do.

You see, in addition to all of the psychological effects we’ve learned so far, our brains are subject to quite a few more. The most important of these might be the spacing effect. It states that things become infinitely more memorable if we repeatedly encounter them. You should also meet its supportive cousin, the lag effect. It states that the spacing effect is compounded when encounters are spaced out for extended periods of time. What I’m trying to say is this: learning something once, no matter how well you do it, just isn’t enough. In his early work, Ebbinghaus found that there were tremendous benefits to continued review—even if he believed he “knew” the material. He called this technique overlearning, and it’s an essential part of creating memories that stick.

Fortunately, there’s a smart way to do this—a way that minimizes wasted time and cuts things down to the minimum effective dose. The fact is, most review is incredibly wasteful. Think back to your grade school days and those flashcards or summary sheet you undoubtedly made for that one big exam. Do you remember that feeling of working your way through that review and knowing the vast majority of the material? Sure, once in a while, you would get stuck on something you knew was challenging for you. But the rest of your study time? I think you get where I’m going.

Since Ebbinghaus’s day, people have concocted a few clever solutions to this little conundrum. One such solution is the Leitner box, a system of organizing your flashcards into five separate boxes. As you study, you move your cards between the boxes depending on how well you understand the information. As you reorganize the cards, you review each box more or less frequently, based on how hard each box is.

This system works quite well, but it requires some serious discipline and organizational skills. What’s more, it’s far from portable. All it takes is a cat jumping on the table to completely ruin everything!

This is why, in the modern era, software developers have taken this concept and digitized it. Today, there are a range of spaced repetition systems (SRS) out there. These include the completely free Anki, the former memory champion Ed Cooke’s Memrise, and even new upstarts, such as Brainscape.

The idea behind digital SRSs is quite simple. Create flashcards—or download someone else’s—complete with audio, video, pictures, and text. Then, start reviewing. For each piece of information, tell the software how difficult it was to answer, on a scale of one to four. The algorithm then considers your answers and reaction times and predicts when you’re likely to forget that card. If you answer “easy” within a few seconds, you’re unlikely to see that flashcard again for weeks—or months! If you struggle before admitting defeat, the flashcard will come up again during that study session. In fact, you’ll see it again and again, until it’s easy. Then, it will come up again tomorrow, and the day after that, until you can consistently answer quickly and confidently.

The end result is a whittling down of the amount of review necessary to learn large amounts of information. This allows you to either save time, if the amount of information you need to learn is fixed, or to pile on new information sooner. When I was learning what I thought was basic Russian vocabulary, I was able to learn up to thirty or forty new words in just a few minutes a day using Anki. This is because I wasn’t wasting any time reviewing words I knew well. By the way, because you’ll forget just about anything on a long enough time scale, SRSs help by providing even the most occasional reminder. In my Russian vocabulary deck, I have words that require review once every year or two. Just that simple review is enough to ensure I never forget them.

If you want to learn a subject fast, SRSs are a veritable secret weapon. Using apps like Anki, my students have passed the bar exam, become doctors, learned seven languages, and much, much more.

It really makes a huge difference.

Now, before I set you off to download Anki or the like, let me warn you. These software systems are developed by people who geek out on both memory and software development. The end result is that many of these apps have a sort of Jekyll and Hyde vibe. They seem simple enough when you use the web app, but download the desktop app, and you’ll soon discover a sea of options, tags, menus, preferences, and databases. It is seriously overwhelming and immediately puts off many would-be users.

My suggestion is to keep it simple. Create individual decks for the things you want to learn, such as human anatomy, Norwegian vocabulary, or the chords on the piano. Avoid spending too much time customizing the format or getting fancy with different templates. Also, if you decide to take advantage of the free, open-source decks that others have shared, be careful. Whatever you do, ensure that the cards are sorted, accurate, and that they import correctly. The last thing you want to do is learn words like трубка if you don’t have to.

But what about things you learn from books? Most of us read books to gain a general knowledge and perspective of new ideas, not to memorize the individual facts, figures, and quotes. For this reason, it doesn’t really make sense to import each of your highlights into a spaced repetition system. Chances are, you don’t care to memorize them like you would vocabulary words. Nonetheless, you do need to perform some kind of spaced repetition or overlearning if you don’t want to forget everything you’ve read.

To make this easier, there is a range of options, depending on what your goals are. For years, I’ve been a big advocate of reading on the Kindle, for one simple reason: Amazon allows you to log on to their website and download or export your highlights. From there, you can put them into a document on your computer or into a cloud-based solution like Evernote. You could even set a reminder to periodically notify you to review these notes. (Yes, the Kindle app does have its own flashcard software built in, but in my opinion, it’s rudimentary and not user-friendly). What’s more, you could even take your highlights, write out the key ideas you want to remember from a book, and load that into Anki. Its algorithm would then determine how frequently you need to be reminded of those points.

Let’s be honest, though: How often are you actually going to do that? I don’t know about you, but I’m usually too excited about the next book to go back and review the last twenty I read.

More recently, however, a member of our team discovered a phenomenal app that takes care of all that. It’s called Readwise, and the premise is very simple. Connect Readwise to all of your highlights (Kindle, Apple Books, Instapaper), and tell it about all of the printed books you’ve read. It will then create a database, adding to it the common highlights from books you’ve read in print or via audiobook, and send you a daily or weekly email of these highlights. What I love about Readwise is that it determines how frequently to send me highlights and then takes the burden of review off of me. All I need to do is read one email per week (or per day), and I’m performing spaced repetition on all of the books I’ve ever read. I like Readwise so much I’ve actually negotiated a two-month free trial for my readers. You can claim it by visiting www.readwise.io/superlearner.

One final note on spaced repetition. At the beginning of this chapter, I explained that visual mnemonics are not enough without spaced repetition. Well, it turns out, the converse is also true. As you dive into the world of spaced repetition and optimize your review, don’t forget everything you’ve learned thus far. Always create visual markers—even if you don’t add pictures to your flashcards. Where appropriate, remember to place those markers into a memory palace. This will supercharge your spaced repetition and save you even more review time. Some students even choose to add a custom “location” field to their flashcards. This is likely unnecessary, but it certainly keeps you honest. One great example of combining these techniques comes from my friend Gabriel Wyner, author of Fluent Forever. In the book, he teaches his meticulous method for combining memorable photos with spaced repetition software. With this method, Gabriel was able to learn four languages—simultaneously. Gabriel is now developing his own SRS, Fluent, which helps people learn languages in this way.

When you combine spaced repetition with the mnemonic techniques you’ve already learned, anything is possible. Plus, it takes a lot less time.