←Notes

Remember anything forever

Recently, I watched a Netflix documentary on memory competitions that tracked four people on their journey to the 2017 World Memory Championship. It briefly covered the winner of that year's championship, Alex Mullen, who was able to memorize a deck of cards in 15.61 seconds. A year later, Shijir-Erdene Bat-Enkh set a world record by memorizing a deck of cards in 12.74 seconds. I was amazed and became briefly obsessed with figuring out how these memory athletes were able to recall so much information in such a short amount of time.

I realized that I wanted to learn about memory techniques for a few reasons:

  1. I love the idea that I might be able to work more efficiently if I can recall things immediately instead of looking them up over and over.
  2. When knowledge is internalized, we make connections between things we already know and use this understanding to help contextualize things we learn later. Knowledge is a snowball that grows as it accumulates more knowledge.
  3. Turns out that with enough practice, anyone can improve their memory with these techniques. Memory athletes don't have a genetic advantage.

These are all enticing reasons to get started, but before diving into an intense memory training regimen, realize that learning something deeply takes time and effort. Even if you master these techniques, you'll probably still forget where you left your keys, unless you remember to remember. Remembering is deliberate!

Here, I'll bring together everything I know so far about memory techniques and how they work.

Techniques

If you've taken a psychology course, you might know that working memory is limited to about 7 ± 2 items; we're only able to recall lists of about seven items at a time. So how are memory athletes able to recall so many items? They anchor new information to information already stored in long-term memory or encode more information into each item.

Humans tend to remember spaces, images, and stories better than things that are more abstract, like letters and numbers. So, we can make words and long sequences of numbers more memorable by generating images from them. We also tend to remember things that are emotional or unusual.

Mnemonic major system

The mnemonic major system can be used to generate words from numbers.

In this system, each digit is assigned to one or more consonants (see the mapping in the table below). We swap digits for letters and use these letters to create words, filling in vowels or other consonants not covered by the major system (like "h", "w", and "y") . 3 is the "m" sound and 5 is the 'l" sound, so 35 translates to mall, meal, or melee. It would be incorrect to encode 35 as smile because "s" would be decoded as 0, resulting in 035.

NumberCommon SpellingsIPA SoundsExamples
0s, z/s/, /z/soup, zebra
1t, d/t/, /d/tall, dance
2n/n/bin, kneel, gnaw
3m/m/flame
4r/r/hurry, race
5l/l/hello, locate
6ch, sh, j/tʃ/, /dʒ/, /ʃ/, /ʒ/chill, cash, jelly, college, vision
7k, g/k/, /g/calendar, bake, chaos, golden
8f, v/f/, /v/face, lava
9p, b/p/, /b/peach, brew

Let's apply this system to memorize the first 16 digits of Euler's number e: 2.718281828459045.

2718 -> negative
28 -> navy
18 -> dove
284 -> never
590 -> helps
45 -> early

It's much easier to remember "negative navy dove never helps early" than to remember the numbers on their own. To translate back into digits, we remove the vowels and any non-major-system consonants and use the table above.

Try it yourself! See if you can find words to match the first 16 digits of the Golden Ratio: 1.618033988749894.

It takes some practice to get good at thinking of words that match the numbers and then converting words back into numbers. When I get stuck, I use Pinfruit to generate words.

Person-action-object system (PAO)

The person-action-object system is a more involved technique for memorizing numbers, but it's useful for memorizing longer sequences.

To use this system:

  1. We assign a person, action, and object to every number between 00 and 99, inclusive. The actions and objects should be closely related to the person.
  2. We chunk six digits at a time, grouping them into three pairs.
    • We take the person associated with the first pair.
    • We take the action associated with the second pair.
    • We take the object associated with the third pair.
    • We combine this person, action, and object to create an image.

Example

For the number 35, let's go with Person: Steph Curry, Action: tossing, Object: basketball, since 35 is Steph Curry's jersey number. Alternatively, using the major system, we could have associated Steph Curry with the number 74 (Curry) or selected any other arbitrary number between 00 and 99.

Try to make these connections unique and meaningful. If you choose Steph Curry, avoid also choosing Michael Jordan, unless you can be sure you won't confuse their actions and objects.

These number associations will be different for everyone. For this example, I came up with and listed three other person-action-object groups in the table below. (Try coming up with 100 PAOs on your own!) We'll use these PAOs to remember this sequence of numbers: 197435863519351974.

NumberPersonActionObject
19Adelesings intomicrophone
35Steph Currytossingbasketball
74Gordon Ramsaycookssteak
86Luke Skywalkerfightslight saber

These are the scenes created by taking six numbers at a time:

  • 197435 -> 19-74-35 -> Adele cooking a basketball. (She has a wok with a basketball inside it, flames coming out over the stove, and you can just smell the rubber. But I set FIRE...)
  • 863519 -> 86-35-19 -> Luke Skywalker tossing a microphone. (Luke is standing way too close to the speakers and causes some really loud feedback, so using The Force, he tosses the microphone as far as he can.)
  • 351974 -> 35-19-74 -> Steph Curry singing into a piece of steak. (He's belting Celine Dion's "My Heart Will Go On" into a piece of steak in his hand, meat juice flowing down his arm and dripping onto his jersey.)

With a bit of effort, we were able to encode one image for every six numbers we were given. This system lends itself to generating absurd images, which is great for making things memorable.

More advanced memorizers use a set of 1,000 images, assigning a person, action, and object to each number between 000 and 999. This allows them to recall one image for every sequence of nine numbers.

Memory palaces and the method of loci

The PAO system is great, but as the number of images increases, it can be difficult to remember their sequence. To remedy this, we can store images in a memory palace and use the method of loci to move between them. This technique exploits our ability to remember spaces really well.

A memory palace is a location that you find memorable, like your house, your office, or a video game map. The method of loci involves imagining yourself visiting places (loci) within this location in a pre-determined order while adding images to each place. As you walk through the memory palace in the pre-determined order, you should be able to recall the images you stored at each locus. Memory athletes sometimes physically visit the location of the memory palace to keep their memory fresh.

Example

Let's choose our house as a memory palace and build on our previous example. Notice how we not only place the images, but also make an effort to integrate the image with the location.

We'll start right outside our front door and place Adele cooking a basketball on the front steps. She's struggling a bit because the warm weather combined with the heat of the wok is making her sweaty. As we walk into our house and into the living room, we see Luke Skywalker tossing his microphone. It makes a dent in the wall right above the TV and falls onto the ground with an amplified thud. Moving into the kitchen now, we see Steph Curry singing into his steak. Behind him the refrigerator is open and is overflowing with steaks.

Tips

  • Always visit a particular memory palace in the same order to simplify recall.
  • Memory palaces can have hundreds of stops, having multiple points of interest within each stop.
  • A memory palace doesn't have to be a building — it can be a path through town or stops on a bus route.
  • Memory palaces can be reused, but there is the risk of seeing an old image instead of a more recent one. Creating many memory palaces is unsustainable, so it may be best to let the older image fade before adding a newer one. (Memory athletes can have dozens of memory palaces and may use memory palaces to remember them all.)

Spaced repetition software (SRS)

Over time, associations between loci and images fade as we begin to forget them. To commit images into long-term memory and improve information recall, we can use spaced repetition software to review.

These systems use flashcards to remind us of information just as we're about to forget it and use algorithms to determine when to review each card. Memory decays exponentially, but decays more slowly if we are reminded of the memory at scheduled points in the future. Because of this phenomenon, the time commitment required to review these flashcards decreases and the time between each review session increases over time.

We can use SRS flashcards to remember the 100 images created for the PAO system, the number-consonant associations used in the major system, or the images associated with the loci in our memory palaces.

One of the most popular SRS apps, Anki, uses a modified version of the SM-2 algorithm developed by Piotr Woźniak of SuperMemo in 1990. SM-2 is commonly used for spaced repetition apps because it's easy to implement, open-source, and does not require a license. SuperMemo's upgraded algorithm, SM-17, offers some benefits, but it's commercial and proprietary.

Applications

The techniques above can be adapted, extended, or combined to fit different types of information. Note that there isn't just one "best" way to memorize anything; memory athletes make modifications and figure out what works best for them. Here, I'll document some of the strategies I've come across.

Memorizing binary numbers

We've covered how we might memorize long sequences of decimal numbers. Memorizing binary digits requires a few extra steps.

Memory athletes become proficient at reading 10 binary digits at a time and convert them to a decimal number between 0 and 1,023. Using an extended version of the PAO system with 1,024 distinct, pre-memorized images, they generate scenes for each set of 30 binary digits and place them in a memory palace.

Memorizing a deck of cards

We can use the PAO system and combine it with a memory palace to memorize a deck of cards.

  1. Associate each of the 52 cards with a unique PAO. We might choose the people based on the suit. For example, friends and family might be hearts, comic book heroes might be spades, etc. Additionally, we can use the card's value and the major system to remind us of the person's name. An seven of spades (7♠) might be Captain America throwing his shield.
  2. Take three cards at a time from the deck, generating imagery from the associated PAOs, just as we would with digits.
  3. Store the sequence of images in a memory palace. This technique allows us to store three cards as one image, using a total of 18 loci for a 52-card deck.

Memory athletes have taken this further and have come up with an even more elaborate system. Instead of relying on PAO to generate images, some athletes pre-memorize images for all possible two-card combinations (52 * 51 = 2,652 images) and store three images at each locus of their memory palace. This results in a total of 9 loci for a 52-card deck.

Memorizing names and faces

One way to match names with faces is to pick a distinguishing facial feature and generate a story from the feature and their name. USA memory champion, Nelson Dellis, elaborates on how to do so in his video on how to remember names and faces.

I've also read about mental athletes encoding facial features (hair color, eye color, etc.) into numbers, turning the number into words, and turning those words into memorable images with the methods above.

Memorizing foreign language vocabulary

To memorize foreign language vocabulary, it may be helpful to use the memory town technique, an extension of the memory palace technique. Alex Mullen demonstrates this technique in his video on learning Chinese vocabulary. Here, Mullen has memorized a person for every consonant sound and a location (a section of a town) for every vowel sound, including its tone. He places the person in the location and generates an image that includes the word's meaning. A description of the image is included in his SRS (Anki) flashcard along with the word and its definition.

Conclusion

I've only scratched the surface of the world memory training. There are tons of memory techniques that I haven't mentioned here, and it seems like people are coming up with new techniques all the time. One thing I noticed in my research is that these techniques are highly composable and can be customized depending on what we find personally memorable.

If you want to learn more about the world of memory training, I would highly recommend checking out the resources I've listed below.

Resources

General information

Spaced repetition