Why Do We Forget?

Wouldn’t it be fantastic if our memory were like a video camera, allowing us to choose what to remember and what to leave behind? And what if we could remember everything? For better or worse, memory doesn’t work that way. But forgetting is not a flaw of memory. Thanks to forgetting, we can reason and imagine.

21 de mayo de 2024

The Forgetting Curve

In the late nineteenth century, Hermann Ebbinghaus was the first to scientifically study how memory works and made some fascinating discoveries. The first one was that as soon as we learn something, we begin to forget it. His experiments resulted in a graph known as the forgetting curve, which showed that the first hours after an experience are when we forget the most. What we still remember a few days later is less likely to be forgotten.

Ebbinghaus also observed that sleep contributes to consolidating what we’ve learned. In particular, it was much more effective to review learning by spacing out the review sessions rather than doing them in close succession. Concentrating—massing—learning made it more short-lived.

Ebbinghaus’ forgetting curve.

Explaining Forgetting

Although it may seem at first that we forget something because it’s no longer in our memory, there’s actually another common reason why we forget: even though it remains in our memory, we can’t find it. How many times have you experienced that feeling of having something “on the tip of your tongue”?

From a neuroscience perspective, much of forgetting appears to result from the changes that have occurred in the brain to remember certain information, such as connections between specific neurons, gradually dissipating over time. However, from a psychological viewpoint (which studies forgetting by assessing whether people can remember information or not) it’s not always clear whether what we’ve forgotten is truly gone or simply not accessible. This is evident because forgetting is not always an accomplished fact: sometimes we don’t remember something, but a clue can jog our memory as if it were nothing. Other times, we may not recall something—for example, an actor’s name—but if someone tells us, we can recognize it.

Memory athletes are individuals who have trained to achieve impressive memory feats, such as remembering lists of thousands of numbers or words. However, they can only do this with the specific materials they have prepared for. Their memory is not extraordinary for remembering everything.

Is It Desirable to Remember Everything?

Since the scientific study of memory began, science has described some individuals with an extraordinary capacity for not forgetting. The Russian psychologist Alexander Luria came across a man, Solomon Shereshevsky, who could retain lists of hundreds of items with just one hearing and recall them years later with virtually no errors.

An American savant called Kim Peek unintentionally memorized all the information that came his way and, over his lifetime, stored the contents of tens of thousands of books word by word in his memory. Similarly, Jill Price can remember any day of her life as if it had happened yesterday. However, these exceptional individuals who hardly forget usually share a common problem: they struggle to make abstractions and use what they’ve learned in new contexts.

Indeed, forgetting is not a flaw in our memory but the way we rid ourselves of the superfluous details of our experiences and retain their meaning. This allows us to relate experiences and apply what we’ve learned in new situations to solve them more effectively. In other words, forgetting enables us to reason and imagine because reasoning and imagining involve combining information from different experiences. To see the relationship between them, we need to trim away the specific details and focus on the common background—if you think about it, most of what you know, you don’t remember when or where you learned it. Concrete memories become knowledge by shedding the details that tied them to a particular experience.

Kim Peek once interrupted a play because an actor changed the line of a text slightly. “I thought no one would notice”—said the actor. “Shakespeare would have noticed!”—Kim responded irritably.

How to Fight Forgetting

It would be great if we could, but memory can’t be trained in a general sense, as if it were a muscle that could be strengthened to remember everything better. Memory only becomes stronger in specific areas where we acquire a lot of knowledge. This is what memory athletes do to remember specific items (such as numbers), but this training is specific to what they study and doesn’t provide them with an exceptional memory for other things.

Certain actions help us remember what we want to remember better.

Although we can’t improve our memory in general, we can use it more effectively. For example:

Think about the meaning of what we’re learning, instead of trying to learn it verbatim. Our memory is much more effective at remembering the meaning—the background or the general idea) of our experiences—rather than specific details.
Look for connections between what we want to remember and things we already know. Analyze what you want to remember and find the knowledge you already have to link them together. It greatly helps in remembering it in the future.
Visualize mental images or turn what we want to remember into a story. Whenever possible, represent the information visually in your mind or create stories that contain it to help you remember it.
Review multiple times but spaced out over time. Spacing out reviews is essential for making memories last. It’s even more effective if you can sleep between reviews.
Use your reviews to test yourself instead of just rereading the information you want to remember. When you put in the effort to retrieve from your memory what you don’t want to forget, you strengthen it more or at least make it more likely to be retrieved in the future. Self-assessment solidifies your learning.