The way you think your memory works is wrong, and that matters.
It’s not just you that’s been led astray.
The way most people think memory works is wrong, and this mistaken understanding has had enormous consequences, from the way the justice system works to the way people think they best learn.
The brain is a complex system, and it’s hard for us to wrap our mind around it. It’s not surprising therefore that we take shortcuts.
We take something we understand intimately, say, a computer, and use it to stand in for the complex thing we want to understand better: our brain.
If the brain is a computer, then memory is the hard drive.
It is a simple enough leap to make. After all, both store information, one in wet brain matter, the other in hard electrons.
We deal with hard drives all the time. From computers to smartphones, to new smartwatches and the hundreds of thousands of computer servers up in the cloud, hard drives are all around us.
We know how they work. We upload information in the form of files which they then store until we need those files again in the future.
If our brain is a computer, and memory is like a hard drive, it only follows that they should work much the same way.
Except they don’t.
Our memory works nothing like a hard drive.
They couldn’t be any more different. They both store information, but that’s about all they share with each other.
A hard drive doesn’t forget. The upload of a file is a passive act. To open a file, you need only click on it.
You forget. You don’t learn by being a passive receptor of the outside world. Remembering doesn’t happen automatically.
Using a hard drive to stand in for memory is like using sugar instead of salt. They might look similar to the eye but using one to stand in for the other will ruin your cooking.
Nevertheless, despite the differences between the hard drive and our memory, research has shown that people think they work much the same way.
In 2011, the psychologists Daniel Simons and Christopher Chabris surveyed close to two thousand people to find out how they think their memory works. They found that more than half of those they asked agreed that memory works much as a video camera does.
Granted, a video camera is not a computer, but when it comes to memory, they share deep commonalities.
A camera accurately records what is happening. Your video of the lady in the red dress twirling around under the sun will not randomly make the dress blue, and the lady an angry man.
What you point the camera towards is what gets recorded.
Once it has been stored, the video file doesn’t lose random frames over time. Those joyous minutes you captured of your children playing around in the sand will still be there for you to look back on. All you need to do is to open the file and let it play.
It would be great if our memory worked like this.
It would make life easier if all we had to do was point our eyes to the book opened in front of us and instantly have its contents become imprinted in the photographic film of our minds.
Alas, if only it were that simple.
Of course, people don’t literally think memory is a hard drive or a video camera.
It is an analogy, and as we shall see, the analogy of memory as a hard drive is merely a single example of a broader category of misleading analogies of memory that have been throughout the centuries to think about how memory works.
These misleading analogies, and the false understanding they give us, have in turn blocked us from using the powers of our memory to their fullest extent.
The power of analogy
When people say that memory is like a video camera or a computer, they don’t mean it literally.
It’s a metaphor. Or rather, an analogy.
Analogies are shortcuts. When we use an analogy, we say something is like something else.
We use analogies all the time.
Her voice was like music to my ears. You need to blow off some steam. Some people are early birds, others are night owls. Love is a battlefield. Life is a journey.
When the poet Dylan Thomas wrote - “Do not go gentle into the good night”, his haunting words borrowed our understanding of the blackness of night and applied it to death, that ultimate darkness.
Analogies are powerful.
Oftentimes the best way to understand something is to come up with the right analogy.
If you’re learning about mitochondria, you can get a boost in your understanding if you think about it as the furnace of the cell. You know what a furnace is. You put fuel in and get energy in the form of heat out. It is the same with mitochondria, except instead of heat you get ATP, and instead of using wood pellets as fuel you use glucose.
The right analogy is rocket fuel to your understanding. On the other hand, the wrong one can act as a weight that drowns you in a sea of confusion.
The difference between enlightenment and ignorance can be in the analogies you use to make sense of the world, and much of the confusion people have about memory stems from the analogies they use.
It has been this way since ancient times.
All the way back in Ancient Greece, Plato had Socrates likening memory to a wax tablet.
For the ancient philosopher, learning amounted to knowledge inscribed to a wax tablet residing within your mind. The markings left where the stylus scored the wax were your memories.
The wax tablet was how people wrote things down in Ancient Greece. It was how information propagated forwards in time. It is not surprising that Plato chose the wax tablet as the technology with which he thought about memory.
By using the wax tablet as the analogy of choice, Plato could reason about why people forget (the marks left in the wax table withered away with the passage of time) and why some people had more trouble learning than others (their wax tablet was hard, thus the stylus could leave no marks on it).
More than two thousand years separate the wax table of Plato to the hard drive of today, yet for all that distance, as metaphors for memory, they share striking similarities.
The first has to do with learning and how knowledge enters our mind.
For the wax tablet, learning is the wielding of the stylus as it traverses around the wax tablet.
For the hard drive, learning is the upload of a file.
In both cases, learning amounts to an imprint of the outside world into a permanent storage location. For both wax tablet and hard drive, your memory is but a passive recipient in the learning process.
The second has to do with forgetting, or the lack thereof.
Sure, Plato talked about how the wax tablet lost the definition of its marks with time, but that is happenstance. Lock the wax tablet away in a hermetically sealed vault and nothing will be lost.
A hard drive doesn’t forget. The photos you saved of your kids when they were young will still be there years from now.
In both cases, information stored is stored forever. If you can get it in, it stays there. Indefinitely.
The third similarity between the wax tablet and the hard drive is that retrieval is effortless.
To retrieve a memory from a wax tablet you need only read its contents. To retrieve a memory from a hard drive you need only double-click the file you want to open.
The parallels between the wax tablet and the hard drive of the computer are striking and point to a deeper structure in the way that people have commonly thought about memory since ancient times.
The archival metaphor of human memory
We’ll call this overarching structure that unites the hard drive, the wax tablet, and the video camera the archival metaphor of memory.
The archival metaphor of memory is the central metaphor from which most other memory metaphors emerge from, and it is how most people think their memory works.
To put it simply, the archival analogy of memory sees memories as distinct blocks of information that get stored in a unique location inside our memory.
Think books in a library, or marks in the wax tablet, or bytes in a hard drive.
In the archival metaphor of memory, a memory is a record of experience. Once you give a book to the librarian, the librarian stores it in its appropriate row on the shelf. To retrieve a memory, you need only pull the book back from its shelf.
The great psychologist William James offered another example of the archival metaphor of memory when he likened memory to a house. To retrieve a memory was to “rummage our house for a lost object.”
One would think that if such eminent people as Plato and William James made use of the archival metaphor to think about the functioning of human memory, it would be because there was something to it.
Yet, the archival metaphor of memory is wrong.
It fails to capture many important aspects of the way our memories work.
Forgetting is inescapable.
A computer doesn’t forget, but we do.
Files stored in a computer don’t wither away with time.
Yet, as I am sure you’ve painfully been made aware, our memories are brittle things.
Memory scientists have measured the speed with which memories are forgotten. The curve displaying these measurements is called the forgetting curve.
The forgetting curve of a computer is flat. Our forgetting curve is an unforgiving downward slope, so steep that our memories cannot but fall alongside it.
Even though we all understand we forget things, it can be hard to make that knowledge come alive when we are going on about our day to day lives.
Researchers talk about foresight bias, where people believe because they remember something now they will also remember it in the future. This bias is also sometimes called the stability bias because people believe their memories to be stable.
Because of the insidious nature of biases, even if you know that you forget, it can be hard not to think that because you know something now you will also now it later. In other words, foresight bias makes us think intuitively of our memories as a hard drive.
How many times has it happened that you’re reading a book sure in the knowledge you will remember what you’re reading a year from now?
If memory worked like a computer, where information is stored perfectly in a crystalline cocoon until the end of time, you would be correct.
Yet, we forget.
Without remedial action, our memories slip away from our fingers.
Even if forgetting is inescapable, there are things we can do to stem the tide of forgetting.
Spaced repetition is one such thing. Research has demonstrably shown periodically being exposed to pieces of information makes them become deeply rooted in our minds, meaning that even though we cannot ever attain the perfect memory of our computer, we can work towards it.
I wrote more about the science and practice of spaced repetition here.
Learning is an active process.
How many students would you guess are currently hunched over hefty textbooks reading small print chapters hoping to suck up as much knowledge as possible for the coming exam?
But does reading the textbook work? Are those students making good use of their time to prepare themselves for their exams?
If they were a computer, sure.
For a computer to store something, you only need to download the file you want to save. By extension, to get something into your mind, to upload knowledge to your memory, you only need to read it.
When researchers ask students what their most common strategies to prepare for their exams are, reading always comes as the number one answer.
You don’t need extensive surveys and complex statistical analysis to come up with this conclusion. Head to any college library and see for yourself. Some of these students even arm themselves with a multicolored battery of highlighters which they proceed to use to light up their textbooks like a Christmas tree.
Reading the textbook multiple times seems like it should work, yet you couldn’t devise a more inefficient learning strategy than reading.
Science straight up says what most students do to learn doesn’t work. A comprehensive review of the literature on effective learning techniques rated rereading, which amounts to reading the same text multiple times, as having ‘low utility’.
Students don’t get much out of it. They think they do, which is why so many do it, but it’s mostly a waste of time.
Learning is not a passive process.
We cannot expect that the mere act of our eyeballs passing over words in a textbook will be enough to get them to stick.
To learn effectively we need to actively participate in the process. We need to get our hands dirty.
A key concept in memory research is the notion of depth of processing. The deeper you process something, the more deeply rooted it becomes in your mind.
The passive reading of a textbook is shallow. You are merely a passive receptacle for what’s written in the textbook. You are not engaging with it.
Writing down your understanding of something in your own words is deep. You are an active participant in the learning process. The act of writing things down forces you to engage with the information you’re trying to learn.
The archival metaphor of memory hides the distinction between shallow and deep processing. It has no way to make sense of it.
Remembering is not automatic.
How do you remember something?
If you were a computer, remembering would amount to double-clicking the correct file. Remembering is never in question.
However, how many times has it happened to you that an answer to a question you were struggling with on an exam came to you after you turned it in?
You couldn’t remember what the answer was during the exam. You thought you’d forgotten it, but after turning exam in the answer suddenly jumped out from whatever hole it was hiding in.
You didn’t forget that knowledge. If you had, you wouldn’t have remembered it afterward. The memory was still buried somewhere within your mind.
You just couldn’t access it.
To a computer, this makes no sense. When you double-click a file, the computer doesn’t tell you “You know what, maybe not today. Try again later when I’m in the mood.”
But you’re not a computer.
You’re a flesh and blood human, with a flesh and blood memory, and that memory comes with its own peculiar intricacies.
Memory scientists distinguish between the storage strength and the retrieval strength of a memory.
Storage strength is about how deeply embedded a memory is in your mind.
A memory high in storage strength isn’t going anywhere soon. It has roots all around your mind and those roots are strong and healthy. A memory low in storage strength is a fragile thing. The gentlest gust of wind will pluck it away from your mind.
Retrieval strength is about whether you can access a memory.
A memory high in retrieval strength is like a dog wagging its tail trying to get you to play with it. It is always ready to play fetch. If you call it, it will come. A memory low in retrieval strength is like a moody teenager that never wants to do anything with his parents. You may ask whether he wants to do anything with the family, but he would rather sulk away in his room alone.
Storage and retrieval strength are independent of one another.
You can have a memory high in storage strength you can’t access, or a memory high in retrieval strength that will soon be forgotten.
Your childhood phone number has high storage strength, but low retrieval strength. It will take you some effort to pull it from the depths of your memory (low retrieval strength), but it is there and likely will continue to be (high storage strength). When you’re in a hotel, your room number comes easily to mind (high retrieval strength) but a day after you’ve checked out from the hotel, you’ll already have forgotten it (low storage strength).
Memories you can’t access makes no sense in the archival metaphor of memory.
For the archival metaphor, if you have a memory, you can access it. If you have a file on your computer then you can open it. If a library has a book on its shelves, then the librarian can go there and grab it.
The archival metaphor papers over the issue of retrieval.
Retrieval matters just as much as storage. What use is having memories you can’t use?
You can increase the storage strength of a memory all you want, but if its retrieval strength is low, if you can’t access and use it, then why bother putting in the effort at all.
How, then, do you increase the retrieval strength of a memory?
By retrieving it.
Using a memory makes it easier to use again in the future.
When you retrieve a memory, you’re telling your brain to keep it ready at hand.
On the other hand, if a memory has not been used after a long time your brain will take notice of that and put it at the back of the warehouse alongside other dusty and rarely used memories. Those memories that are regularly used go to the front shelves, ready to be picked up on a moment’s notice.
Once again, the archival metaphor of memory can make no sense of this. The files on your computer don’t become stronger after you open them.
Unlocking your memory’s full potential
By thinking of memory as its own thing, with its own peculiarities and intricacies, you’ll no longer be at its inscrutable mercy. When properly understood, memory is a wonderful thing, and by laying the archival metaphor to the side you will be able to take full advantage of your memory.
Once you take memory for what it is, rather than what you think it should be, you will stop wasting your time with inefficient learning techniques that would only work if your memory were a computer.
It is only after you’ve left the archival metaphor behind you that you begin to understand that the techniques that work are not intuitive, they do not feel that they should work, but they do.
It is only then that you can begin to make full use of the power of your memory.
You will begin using spaced repetition because you understand that forgetting happens, and that you need to exercise those retrieval muscles. Anki will be a great help to you in that.
Because you realize learning doesn’t happen passively, you do away with your highlighters and instead repeatedly test yourself on what you’re learning. Where before reading might have made up the bulk of your studying, now it a mere sideshow. Testing yourself is what you think of when you think of studying.
The archival metaphor of memory is a useful one, but flawed. You and I will never get rid of it totally, it’s too useful a crutch to be abandoned entirely.
But it is not to be relied upon.
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