Hermann Ebbinghaus

Forgetting Curves

Memory tricks start with Ebbinghaus’ forgetting curves. He was the first to describe them in 1885. The concept is simple: We forget things. Some things we forget quickly, other things linger in our minds for longer. Whether things are hard or easy to remember does not matter: Forgetting always follows exponential decay (apart from very few exceptions).

If you start out with 100 things that are hard to remember it may take you a day to forget 50 of them. It will then take another day for you to forget another 25, and then a day to forget the next 12 or 13.

Now, if you start with 100 things that are easy to remember it may take you a month to forget 50 of them. It will take another month for you to forget another 25, and then a month to forget the next 12 or 13.

Each piece of information suffers exponential decay. Some knowledge decays faster, some slower. But the time it takes forgetting to half what you know always stays the same.

Revisions are the only way to interrupt forgetting. Things you have forgotten about can not pop back into your mind all by their own.

Flattening The Curves

If we could start with super-flat forgetting curves, knowledge would just stick and we would not have to worry about revisions at all.

If you have a normal brain, unfortunately, most knowledge decays after only 18 seconds. If you want to remember a piece of information for a whole year, you would have to find a way to strengthen your memory by roughly 2,000,000 times!

Revisions are one way to achieve this. But this takes some time and effort. And it is not the most entertaining thing to do, either.

Let us first focus on the first time you ever learn something new. Can we make this stick for longer? Can we make things easier to remember?

What is the actual difference between hard and easy to remember? The simple answer is: Anything useful for your survival in a Savannah is easy to remember. Everything else is hard. Over hundreds of thousands of years, genes causing a bad memory for survival essentials did not spread. Bad memory for everything else, however, did.

All of this still affects modern humans. You can quickly test your own prehistoric capabilities: Do you know where the next river, pond, or lake is? Will you find your way to 5 groceries in your vicinity? I am sure you do! Did you learn that in school? No?

You did learn how long-shore drift works and when the Battle of Waterloo was fought, though. Have you forgotten all about that? Evolution did not mind that our ancestors had a bad memory for these things.

Memory tricks simply fool your mind. All they do is pretend that what is relevant in the modern world (hard to remember) is somehow useful for surviving in a Savannah (easy to remember).

Peterson, L.R., & Peterson, M.J. (1959). Short-term retention of individual verbal items. Journal of Experimental Psychology, 58, 193-198

Wrappers

All we have to do is find ways to wrap things that are hard to remember in something else. Something, that is easy to remember.

Memorizing something by brute force is like a long jump. A single leap. A memory trick replaces it with a triple jump: You use an association, an encoding, and a story. And with a little bit of practice, you can ditch the brute force memorization.

If you think this is a terrible deal you are not alone. Like a long jump, brute force memorization does not take long. A triple jump takes longer. It is also much more difficult to get hop, skip and jump right. But once you are good with it, you can cover much longer distances!

When it comes to things that are hard to remember, the human mind can store a lot more and a lot quicker than with brute force memorization. This is why memory champions use these methods for their competitions. Here are some of their incredible memorization feats:

Memorize 4620 digits in 1 hour
630 digits in 5 minutes
the order of 2530 playing cards in 1 hour
52 playing cards in 12.74 seconds
241 historic dates in 5 minutes

Impressed? Wondering, how this is even possible? Read on …

First Wrapper - Images

How many faces do you think you can remember? How long will it take you to process this text? Probably a few minutes. How long, by comparison, will it take to process an image?

Research into any aspects where our minds thrive is actually rare. It seems that there is no meaningful limit. An average person recognizes 5000 faces and can process an image in just 13 milliseconds.

The simplest wrappers are images. They stick. All we need is a split second to take an image in. We can also easily imagine them in our mind’s eye*. Look at the two elephants. Let us use this image to wrap something that is hard to remember. Let us use them as a reminder for a short story that tells us how to spell b-e-c-a-u-s-e.

Big Elephants Can Always Understand Small Elephants

Images are great to form this sort of association. You can condition your mind so that the elephants pop into your head when you spell “because”. It is not the image that tells you how. It is the little story about elephants that does it. The image is just a memorable link between the spelling and the story.

* 1-3% of us have Aphantasia and can not

Jenkins, Rob, A. J. Dowsett, and A. M. Burton. How many faces do people know? Proceedings of the Royal Society B 285.1888 (2018)

Potter, Mary C., et al. Detecting meaning in RSVP at 13 ms per picture Attention, Perception, & Psychophysics 76 (2014): 270-279.

Second Wrapper - Small Stories

Our minds are great with small stories. We manage our relationships with them. Try it. Think of a person from your childhood and tell me about them! I went foraging with my gran, and to a swimming competition with my best mate. My neighbor brought me to the hospital when I broke my arm, and my auntie lost every single card game she ever played.

These are episodic memories: Stories that we have experienced ourselves. They are very sticky. However, they will fade away eventually. Unless, of course, they are regularly revised. Is your granddad telling you the story about the fish he caught again? He is just revising his episodic memory!

You can use the stickiness of small stories for your semantic memory as well. This is a different part of our memory. It manages concepts and facts. It has no personal context and no emotional connection and is therefore a lot less sticky. But we can make it more memorable when we make the story relatable.

Make them a lot more memorable with emotions: Outrage, disgust, anger, and laughter. Emotions tap into the strength of our episodic memory. So do locations - but more on this a bit later.

Greenberg, Daniel L., and Mieke Verfaellie. Interdependence of episodic and semantic memory: Evidence from neuropsychology, Journal of the International Neuropsychological society 16.5 (2010): 748-753.

Kensinger, Elizabeth A. Remembering the details: Effects of emotion. Emotion review 1.2 (2009): 99-113.

Detour - Amplifiers

With stories, we can prop up our semantic memory. But not all stories are created equal. There are several ways to make them more memorable: Spice them up with personal experiences and emotions. Place them in familiar locations. You can also take advantage of the Von Restorff effect.

The Von Restorff effect is also known as the isolation effect. When multiple stimuli are presented, the stimulus that differs from the rest is a lot more likely to be remembered.

This is why “Big Elephants Can Always Understand Small Elephants” is actually a weak image. There is no emotion. The elephants don’t do anything special. Let’s try and improve it with emotion and make the story stand out. Combine discomfort and an absurd story:

Berries Everywhere Cause An Unstoppable Sneezing Epidemic

Establish the emotion. You have an allergy attack when you have to spell because. Can you feel your eyes itching already? Can you feel a sneeze forming? It is the berries! They are everywhere! They cause an unstoppable sneezing epidemic: We’re all gonna die!

But don’t use my story. Try to find an image and a story that works for you. Then let it pop into your mind when you spell because the next time.

Fabiani, Monica, and Emanuel Donchin. Encoding processes and memory organization: a model of the von Restorff effect Journal of Experimental Psychology: Learning, Memory, and Cognition 21.1 (1995): 224.

Location, location, location

Images are great anchors. But it is difficult to encode more than one fact in an image. What happens if you have a collection of things you want to memorize? This may be a sequence of historic events for a test at school or a list of things you want to talk about in a presentation.

Locations are perfect when you have a lot to memorize. We have developed an almost unlimited capacity for locations. Ever since 1865, London Taxi Drivers are required to memorize 25,000 streets and 100,000 landmarks within 6 miles of Charing Cross. There are somewhere between 5,000 and 10,000 taxi drivers who have passed this test!

Memorizing all of this is hard, but you don’t need the brain of a genius for it. If you tried to memorize 100,000 of anything else you would struggle. Like words in a foreign language, digits of Pi, bird species, or the names of the 20,000 prescription drugs on the market. None of these help your survival in the Savannah. Knowing every landmark within a 6 mile radius does.

Locations are so strong because they are closely linked to our episodic memory. They are stored in the same brain region and give you the most powerful memory aid known. You can use them to attach your other memory tricks - the crazy stories, the images, the word games, or even little melodies and dances!

Let’s have a look how this is done …

Rolls, Edmund T., Simon M. Stringer, and Thomas P. Trappenberg. A unified model of spatial and episodic memory. Proceedings of the Royal Society of London. Series B: Biological Sciences 269.1496 (2002): 1087-1093.

The Memory Palace

We now have all the elements of a memory palace together!

The concept has been used for millennia and was first attributed in 514b.c. to Simonides of Cos. Cicero and many other orators used this and related concepts to memorize hour-long speeches.

You can build a memory palace, too! Just bring the concepts above together. Mastering the skill has huge benefits: Memorize 10 times more and 10 times faster! It takes a little bit of practice, though. Think of it like taking up jogging with a Couch to 5K training plan. Physical fitness has a positive impact on your cognition and you can even combine the two!

You can build your first memory palace for your next important assessment or for a presentation you give to a huge audience. If you are like me, you will probably not trust yourself to jump in at the deep end. You are better off practicing before. Here is how:

(1) Make use of your great memory for locations. You can use a room in your house. You can also use your way to work or school. Or you can put your trainers on and choose a 5K walk or run where you live!

(2) Choose some knowledge you would enjoy memorizing. The names of dog breeds, places that hosted the Olympic games, Picasso paintings … whatever you find interesting. Have a look at the topics in Sproc’s History Quiz. Why not select one topic and memorize all the events?

(3) Encode this knowledge in your walk or run. Select a landmark every so often and attach a story and an image that reminds you of the thing you want to remember. Have Abe Lincoln at your next-door neighbor’s letterbox collect his mail. Instead of a letter, he gets a burger. Battle of Gettysburg - done!

(4) Revise. Walk your walk or go for a jog. Stay mindful: when you pass that letterbox, let your imagination take over and remind you of Gettysburg. No memory aid is bulletproof. You will still occasionally forget things. Make sure you fix any gaps as soon as you can.

(5) Present. Find someone who will patiently listen to what you have memorized. Talk them through your palace - or even take them on your walk!

Practice this a couple of times and become confident with the concept. And then use it for an important presentation or a test you take!

Another Detour: Numbers

Numbers are evil.

First, their whole point is precision. Understanding a historic period or a physical phenomenon almost precisely is much better than no understanding at all. Remembering the PIN of your credit card or a telephone number almost precisely is just as good as not remembering it at all.

And second, we have not evolved any mental structures to remember them. Numbers play no role when it comes to survival on the Savannah. They are so irrelevant that there are still languages spoken in the dense forests of Amazonia today that have no numbers at all.

For numbers, memory champions use a third level of wrapping. They wrap the number in a word or phrase first. Then they wrap the phrase in a short story. The short story gets wrapped in an image. And if they need to, the images get wrapped up in a memory palace.

Memory champions have sophisticated methods to go from a number to a word, which allows them to bulk memorize hundreds of numbers in minutes. For everyday purposes, a simple encoding does the job. You can practice it when you play Quizterix: The Major System.

In this system, consonants translate to numbers and vice versa. You are then left to fill in the vowels so that they make up words. 1815, the date of the Battle of Waterloo, translates to d-f-d-l and you can spot a daffodil in there. You can also just encode the first words of a phrase to get more flexibility. 1815 stands for

Toilet Fatalities!
Tarantulas Lurking in the Loo

Emotion: Fear of Spiders, Von Restorff: Toilet Humour

Condensed Memory Palaces

Memory palaces work with locations but there are great ways to create substitutes. Many cultures have invented alternatives that transfer locations in the real world to locations on artifacts or locations in your imagination.

Lynne Kelly has a great explanation - a story, in fact - for how these techniques might have been invented. Hunter-gatherers used memory palaces to memorize their extensive knowledge about the world around them. Aboriginal Australians, for example, encode much of it in stories that they place in the landscapes around them.

Once agriculture was discovered, people stopped roaming as much and they lost frequent access to revise their palaces. They condensed landscapes. They still could build a palace but it became quicker to navigate. Lynne Kelly suggests structures like Stonehenge and similar monuments across the world are memory aids. Instead of roaming for miles a quick walk around the monument will give a similar result.

The Luba have shrunk this down even further. They use a piece of wood with shards, beads, and carvings. With imagination, it turns into a lush landscape. The Luba build their palaces there. They encode their entire history, their code of law, and the great Luba epic which has 120 pages when you print it in a book - and all on an artifact that fits into your pocket.  

Size is not the only advantage. Landscapes change and you can’t take them with you. You can, however, take your memory board with you. You can create a copy. You can hand it down to a child.

Epics

There is a third way to make stories memorable. Emotions and the van Restorff effect give you memorable soundbites. You can tie them together in a memory palace. For a working memory palace, you can keep them independent of each other. David Reser showed that you can increase memorability further if you manage to weave them all into a coherent epic.

An epic is a long story with a proper narrative. A story with a plot that we can emerge into, and that makes sense. It is much easier to retell the plot of such an epic than a shopping list of random items. But what makes a plot a plot?

Christopher Booker identified 7 basic plots. Almost all narratives seem to follow one of them. Why? Because these stories are memorable. They stick in our minds and spread. They get retold, written down, and turned into movies. We have heard so many rags-to-riches stories that hearing or reading one that is new to us feels familiar. It is clear from the outset who our hero is. We know who the baddies are. We expect the Fairy Godmother to help the hero. And there will be a showdown.

Like a walk in a familiar park, the plot is easy to navigate. The plot can serve as a landscape and substitute a place - just like a memory board. You can set your plot in a real landscape as well. This way you get a strong combination of several memory tricks. And if you do that, you arrive at a method similar to the Aboriginal songlines that turned out to be most successful in the Reser study.

Booker, Christopher. The seven basic plots: Why we tell stories. A&C Black, 2004.

Revision

And here we are. We have managed to flatten our initial forgetting curves. The Great Pyramid of Gizah was built in 2580bc …. close your eyes and 18 seconds later you have forgotten about it.

Now imagine it is nearly lunchtime and a Frankfurter Sausage Geyser erupts. You will be able to hold this imagery in your mind for a lot longer. And even longer with some training. It may last a few hours or even a week. But it will fade into oblivion at some point.

So you have to revise. Ebbinghaus suggests revising when you have a 50:50 chance to still remember. This will multiply your memory strength. If you start out with 18s of memory strength and you revise after 18s you may end up with a memory strength of 3 minutes. If you then revise after 3 minutes, you may end up with a memory strength of 30 minutes. Revise again after 30 minutes etc.

Unless you have a computer managing your revisions, hitting good revision timings is hard. Sproc’s History Quiz is all about using cleverly timed revisions to flatten forgetting curves. It works even when you use brute-force memorization and start out with very steep forgetting curves.

Once you have your memory at a strength of a few days or more, revision timings are much easier to manage: Revising after 1 week when your optimal timing would have been after 2 days does not make a huge difference. Revising after 1 week when your optimal timing would have been after 5 minutes will leave you with no impact on your memory strength at all.

There are two options to cope. If you stick to brute-force memorization, you basically accept that you will forget most things you will ever learn. If you want to put your time to better use, apply memory tricks, get your memory strength to a few days quickly, and revise occasionally.

Start Building memory palaces on walks and combine them with physical exercise. Use memory boards. But most of all: There are great memory tricks you can use to become faster and better at memorizing.

It is easier than you think. Start practicing. Get the skills. Reap the rewards!