Home     About       Contact

Displacement Theory: Why You Can't Remember Your High School Locker Combination

by Jimmy Leonard | Updated 04 Aug 2023

Sueño Labs does not provide medical advice. See our terms and disclaimers.

A hallway in a high school with combination lockers in photographic style
Microsoft Bing Image Creator Powered by Dall-E

Remember 9th grade? Peach fuzz on the upper lip and awkward convos with your crush before the bell rang for third period? I’m guessing one thing you don’t remember is your locker combination. Think about it. If you went back to your high school as an adult and had to find your exact 9th-grade locker and spin the combination, the chances of you finding the right spot and picking the right numbers are less than the nutritional value of Hot Cheetos and cafeteria pizza.

Which is weird, right? At one point in your life, you input that combination multiple times per day, five days per week, for nine months. How can you do something that many times and then forget about it? The answer may have something to do with the displacement theory of forgetting. Our short-term memory deletes stuff that it no longer needs to care about. Turns out, encouraging that kind of clean out might be good for your brain.

Understanding Displacement Theory

The Fundamentals of Forgetting

Speaking of high school, let’s close our eyes and slow jam to Chasing Cars for a moment.

If I lay here
If I just lay here
Would you lie with me and just forget the world?

Every angsty teenager wants to “forget the world” from time to time — as does every angsty full-grown adult — but we know it’s not that easy. When it’s big-time drama, there is no delete button; there is no drag-and-drop into the trash folder of our brains. Yet somehow we do forget all sorts of things every day. Where we left our keys. The words to the song that’s stuck in our heads. What our boss said two minutes ago as we zone out in the Monday morning staff meeting. Why does this happen?

Scientific theories of forgetting often toss around the word interference. Basically, your brain has every intention of remembering, but then something interferes before it can. That squirrel climbing a tree outside the window while your boss is talking. The stress of being late because you can’t find your keys (a vicious cycle, that one). But that doesn’t account for everything. I don’t recall what shirt I wore on this date last year, but I do remember what I wore on my wedding day. That’s easy, right? It was this special, emotional day that naturally imprinted deep into my mind — plus I’ve seen pictures of it a zillion times to reinforce the memory. But an average day of the week? That’s not special — and that’s the key to the displacement theory.

Displacement Theory, Explained

There’s this scene in Sherlock when Watson ribs the great detective for “deleting” the solar system from his brain. Sherlock says, “Ordinary people fill their heads with all kinds of rubbish. And that makes it hard to get at the stuff that matters.”

If we think of the brain like a hard drive, each memory or fact or neurological function takes up space. The theory is that clearing space helps the brain run faster, just like how a computer frees up its random-access memory (RAM). The psychologist William James first proposed the idea that we have short-term and long-term memories in 1890. His theory was that our short-term memory (STM) has a finite capacity — it’s limited, like a cup that can only hold so much water before it overflows. The displacement theory, then, is that new, fresh information takes the place of old information. You’re on the phone with someone, they say something, then you hear someone nearby shout. Most likely, you go back to the phone call and say, “Sorry, what did you just say?” That’s because “words I just heard” was displaced by “shout I just heard,” even in that fraction of a second. 

So what about the locker combination? That wouldn’t be STM — you memorize those numbers early in the year. Brain scientists theorize that there’s a kind of interference that happens with memories of the same type. Maybe you’ve had a dozen different locker combinations, but when you mentally search for the right numbers, the most recent answer interferes with the others. For a more techy example, you surely remember your computer password or phone passcode. But if you were to change them, you may be surprised by how quickly you forget the old password. When the brain doesn’t need it, it deletes it.

Does Forgetting Really Help the Brain?

It’s hard to study this. We can’t really make a control group of people who go about their lives and forget nothing just to see what happens. But I think the fact that computers run slower when their hard drive is full should matter to this conversation. Or, think about cramming for a big test. It is literally exhausting to force information into your STM. Doing flashcards for an hour makes us tired.

The brain gets you from Point A to Point B. It’s not necessarily concerned about the journey. I did some transcription work early in my freelance career, and it’s pretty wild how bad we are at complete sentences. When you’re talking to someone in real life, you rarely notice it. But when you play back a recording, you realize that most conversations actually sound like this:

Hey, can you uh help for a sec?
Sure um I just needta finish this us uh
Yeah that’s fine no rush just whenever is fine

The brain takes this auditory babble and distills it to find the meaning: Can you help? Yes. Focusing on all the sounds in between is a waste of time and energy. Imagine eating a bag of chips at lunch and remembering what each individual chip tasted like. That would be distracting — and pointless. Your taste buds do experience each chip, but the brain is smart enough to aggregate that into one remembered thought.

The Things We Forget on Purpose

So if Sherlock Holmes can selectively delete useless information, can we?

Doing so involves leaning into the displacement theory. The expressions “take your mind off it” and “clear your mind” hold some wisdom here. You can clear your STM by filling it with something else.

Imagine someone says something upsetting to you or you make a mistake and are kicking yourself for it. There’s psychological advantage to replacing those negative thoughts and feelings as soon as possible, but you have to replace it in kind. Words replace words, sounds replace sounds, images replace images. If you see something really disturbing and try to erase it by listening to music, it probably won’t work. If you see something disturbing and then hop on TikTok to watch videos of cute puppies for 15 minutes, that will be much more effective. The brain updates “what I just saw” to something happier.

Try It: Displacement Theory of Forgetting Lab

The next time you have a song stuck in your head, try listening to music to get it out. Replace the song that’s annoying you with another one. Some people report that listening to the stuck song itself also works — the idea is to replace that “I’m stuck” feeling with a more neutral or even positive experience to get past the moment that’s bothering you.

Remember, you have to displace it with something similar. If you’re frustrated at work, taking a walk might help, but you’ll likely still be thinking about work. Instead, try working on something else — update “what I’m working on” in the brain. Your mind will clear its short-term memory anyway, but, when it’s advantageous, you can hurry the process along.

Jimmy Leonard

Jimmy Leonard

Jimmy is a marketing content strategist and copywriter who moonlights as the editor of Sueño Labs. He chooses not to forget the solar system.

© 2024 Sueño Labs                 Contact                 Sitemap                  Terms and Disclaimers

This website is hosted by SiteGround. It’s amazing. Use our referral link to save on a super-fast hosting plan.