Why We Forget Some Memories And Remember Others

This morning, heading out the door to take my 9-year-old daughter to school, I patted my pockets to confirm “phone-keys-wallet.” This is a little ritual intended to keep me from having to run back for any of these essential items, or, worse, from locking myself out of the house.

Once we were on the subway, I remembered that my daughter needed to finish reading a chapter in her class novel. I unzipped her backpack and began searching for the book’s pale blue dust jacket. But it wasn’t there.

At that moment, in my mind, I saw the book sitting on the bedside table. She had forgotten to put it in her bag. My wife and I had forgotten to ask her if she had everything she needed for school. Multiple parties bore responsibility for this mistake. (In theory, we support having our kids be responsible for their own things, and experiencing the natural consequences of forgetting or losing them — but in practice, we offer a lot of gentle reminders in order to prevent trips back up to the apartment.)

My daughter was upset that the other kids would now be ahead of her in the book. I was disappointed to have broken the morning’s winning streak.

On most days, as I’m faced with an unyielding stream of parenting-related demands, something inevitably slips. I forget to make a call, return an email, pay a bill. The problems this creates usually aren’t critical. But they can be inconvenient and frustrating. There’s also the anxiety I feel knowing that something is going to slip through the cracks of my memory and I can’t entirely control what it’s going to be. Today it was the book, but tomorrow it might be making a bank transfer, or taking the chicken out of the freezer to defrost — either of which would create an additional problem for me to resolve.

Is it that I’m particularly absent-minded? Ill-suited to the demands of full-time work and parenting? Do I simply need a better system, maybe some sort of hack to make all of this easier?

Or could it be that my expectations of my own memory are a mismatch with my human brain?

I reached out to a couple of scientists who study the way our memory works, and I’m happy to report that they were both sympathetic and reassuring.

“I think a lot of our everyday forgetting comes from the fact that the amount of information that we have to process at any given time is just massive,” Charan Ranganath, a professor of neuroscience and psychology at the University of California, Davis, and author of the forthcoming book “Why We Remember,” told me.

“We have this expectation that you’re supposed to have a perfect memory of every moment, everything you ever experienced — which is impossible.”

The workings of the human brain, the way that neurons contain and transmit thought, remain something of a mystery. But by using modern imaging techniques like functional MRI, scientists are able to see which areas of the brain are involved in different processes. Studies have also made it possible to find patterns in the way that memory works.

Faced with a constant onslaught of information, our brains have to prioritize what information to hold on to. Where forgetting comes into play, said Ranganath, is when the brain lets go of information that it turns out we need later.

Many of our memories are similar to one another. When we have a new experience or learn new information, we add it to memories that we already have, instead of making a new memory from scratch every time. This makes our brains much more efficient. Instead of re-remembering my whole apartment layout every time I rearrange the furniture, my mind just notes that the sofa now faces the window. This is the salient thing, the piece that changed position.

“When you have a new experience, it’s never really… a brand new thing,” Ranganath said. “You just reuse a lot of those same components over again.”

This ability to add new information to prior understanding enables us to recall more. “A lot of the secret of remembering more is actually encoding less information,” Ranganath said.

But this elegant system does have some downsides. If I’m looking for my keys, for example, I’ve probably seen them in so many different places that it’s hard to recall where I placed them last.

The human brain evolved for our survival, and because of this, we are prone to remember distinctive things that will help us avoid threats to our safety.

“Our brains evolved to help us to remember things in order that we can interpret what’s going on around us, and creatively, flexibly imagine the future and then try to problem-solve,” Dr. Andrew Budson, a professor of neurology at Boston University and co-author of “Why We Forget and How to Remember Better: The Science Behind Memory,” told me.

If we want to remember a mundane thing, iterations of which which we have thought many times before ― such as an image of where our keys are ― we have to make the memory distinct somehow, so that it stands out to our brain as something to hang on to. Ranganath compared it to the way a brightly colored piece of paper would stand out on a desk scattered with sheets of white paper and manila folders.

There are different ways that the brain may access a memory.

The hippocampus, Ranganath explained, is a part of our brain that is good at holding on to the “when” and “where” of memories. Memories can be cued by something — often a particular song or smell will bring us back to a place in time, for example.

The hippocampus becomes activated in what are called “event boundaries,” or shifts in context. If you are having a conversation and you’re interrupted by a text message on your phone, it might take you a moment to “get back on track.” You might ask, “What were we talking about?” In these kinds of situations, when the hippocampus activated, it sort of saved your place for you, acting like a bookmark that can bring you right back to where you were.

Another example Ranganath gave is walking into the kitchen to grab something and realizing you’ve forgotten what it was you came for. In such cases, retracing your steps and returning to the room you were in before can serve to “jog” your memory.

“You just pull up these little pieces and then you kind of follow that breadcrumb trail back to where you were,” he said.

We also rely on a different part of our brain, the prefrontal cortex, to help us hone in on the thing we’ve deemed important and ignore all of the other background noise. The prefrontal cortex is what allows us to focus, and when we’re well-focused, we’re much more likely to remember the moment. (Cue every teacher reminding kids to focus in class so they’ll be able to recall what’s being taught.)

“Probably one of the biggest predictors of being able to form a memory that lasts is that ability to maintain that focus,” Ranganath said.

Emotion is another way that memories can get flagged as important and sealed in. When I said that I feel guilty for sometimes forgetting things that are for my kids (the class novel, the soccer uniform), Budson kindly pointed out that the kinds of things I’m forgetting are low-stakes. What my brain tags as important is done from an evolutionary perspective. It has to do with survival, not my self-image. If my child, for example, took an anti-seizure medication, and I had the frightening experience of seeing them have a seizure at one point, I would surely never forget to give them the medicine.

“Not remembering something, just because it’s related to their child, that doesn’t mean that you’re not prioritizing your children,” Budson said. “It just means that probably deep down you know, whatever it is you forgot is not really important.”

The way parents spend our days, constantly reacting to new information and switching back and forth between contexts, makes it a challenge to commit things to memory.

“There’s always this onslaught of things that you could be paying attention to, and so what that means is you’re just constantly getting these little snippets of your experience and memory, but then they just move on,” Ranganath said. “They’re all disconnected from each other.”

Add to that the fragmented nature of life in the digital age — here an alert, there an email — and parents today are up against a huge number of distractions that can prevent them from making and calling up memories. It’s harder than ever to maintain the kind of focus that allows us to remember clearly.

On top of everything, two things that help our brains function at their peak are sleep and exercise, both of which can be hard for busy parents to come by. Budson is also a proponent of practicing mindfulness, but, like physical exercise, this is something that we have to make time in our schedules for.

We like to think that we have control over our thoughts, Budson explained, but the practice of mindfulness helps us comprehend that actually, it is mostly our unconscious brain that “is deciding what we are paying attention to at any particular moment.”

It isn’t a cure-all, but “practicing mindfulness can help you to control your thoughts better,” Budson said. “And because of that, it will help you to pay attention better to what you want to pay attention to, and ignore what you don’t want to pay attention to.” This focus allows us to best commit information to memory.

Ranganath suggests that, as parents, we should all go a little easy on ourselves. When it comes to things like forgetting to check that the book was in the backpack, he explained, “remembering to do something is very, very hard, because we’re having to do something in the future. That means not only do you have to remember that you’re supposed to do, but we have to remember it at the right time, which hasn’t come yet. So if you don’t have a reminder in that moment, you’re going to be cruising along your day.”

In other words, it would’ve taken a reminder like an alarm on my phone or a sticky note on the front door to remind us to check for the book. It would have required forethought.

When it comes to remembering to do something, “the kind of memory demand that places is huge. That’s very taxing on your prefrontal cortex,” Ranganath said ― particularly “if you’re already compromised from stress and fatigue and distractions.”

Now that I’ve spent the day writing about the forgotten book, I’ll definitely remember to ask my daughter if it’s in her backpack tomorrow. This particular memory is now well-ingrained. But that won’t prevent me from forgetting to send in cans for the food drive, or money for the class trip. There will always be something.

In terms of remembering to do things, there are a couple of ways you can boost your brain’s ability to function. Budson referred to these as memory tools and memory strategies.

Memory tools are things like a shopping list to remind you what items you need to get at the store. Other examples of tools are a calendar, a pillbox, or a note on the refrigerator. Most of us use tools like calendar alerts and reminders on our phones to help us remember appointments, calls, and other things we need to do throughout the day.

As parents, we can help our kids take responsibility for the things they need to remember by making their own reminder notes and checklists.

Memory strategies include things like mnemonic devices. Another trick is to identify some sort of visual cue that you will see around the time or place that you need to remember to do something, Ranganath said ― like “a landmark that sticks out right at the stoplight where you need to turn to go to the grocery store. Then visualize yourself seeing that and then saying, ‘Aha, I’ve got to turn and go to the grocery store and pick up the cake mix.’”

When you see the landmark, “that memory will pop up, and then it’ll serve as a reminder,” Ranganath said. “You’re basically kind of creating a little alert in your brain.”

Testing yourself is another strategy. If you make a list of the four things you need at the store, then quiz yourself multiple times on the way there to see if you can remember them all, you may not need to look at the list once you arrive.

Of course, there’s no shame in making lists and setting digital reminders. Remembering is hard work, and we need to use all the tools at our disposal. But there’s also no shame in forgetting. Our brains evolved for the purpose of keeping our children alive — not always having them in matching socks or earning straight A’s.

“I really do believe that part of why we often feel so broken is because we just have such crazy expectations that, ‘Oh, I should be able to remember all this just because it’s important,’” Ranganath said. “And it’s like, you know ‘important’ is really like a saber-toothed tiger that’s about to tear you apart.”