Memory plays a powerful role in our everyday experiences, including how we learn and recall things, how we make decisions, and how we plan for our future. That is, memory serves as more than just a simple record of the past. What, then, happens to our memories as we get older—and, for that matter, how reliable are our memories at any age?
To answer these and other questions about memory, the Wellness Letter turned to Charan Ranganath, PhD, a professor of psychology and neuroscience at the University of California, Davis, and an expert on the issue. His book Why We Remember: Unlocking Memory’s Power to Hold on to What Matters was published earlier this year.
Wellness Letter: What are we talking about when we refer to “memory”? Are there different categories of memory?
Charan Ranganath: Yes, there are different kinds of memory. One would be the ability to learn physical skills, for instance, which is called procedural memory. Another is the ability to just see or recognize something as being familiar. Then there is the ability to retain knowledge about the world, which is what we call semantic memory. What I study is our ability to recollect individual events, which is called episodic memory. When people use the word “memory,” that’s usually what they’re thinking of.
WL: Do people tend to think their memories are real?
CR: I do think many people overestimate how accurately they remember things. They tend to think, “If I remember something very vividly, it must be an accurate memory.” And that’s not really true. Our brains are economical, so they’re not storing everything. They’re trying to grab just the important stuff from our experiences, what’s new and unique. When you recall the memory, you don’t recall the entire sequence of things, you just recall little bits and pieces that give you a sense of what was unique about this particular event.
The brain reconstructs the story based on that. That means we’re not really replaying the past exactly as it happened or unfolded. We’re making inferences about what had happened based on these little fragments that we recall. Sometimes you might consciously be aware of the fact that you’re doing this kind of guesswork. At other times, it happens so effortlessly, you don’t even know it.
WL: Can you give an example of how this works?
CR: For instance, if you’re remembering a vacation at the beach, you’ll know there’s going to be sand involved somewhere, there’s going to be water involved somewhere. So there are a lot of instances where you can just fill in the blanks from previous knowledge. That gives you a dramatic increase in the amount of information that your brain can encode. And it gives you the ability to deploy that information very quickly. You’ve already got these preassembled chunks about being at the beach. As a result, you can assemble any new memory using these chunks that you already have from past events.
That’s extraordinarily powerful. But we can also put the memory together in a way that’s inaccurate. For example, we might conflate elements of different events into the story. Moreover, just the act of remembering something actually changes your mental representation of it. It creates a new memory. When you’ve repeatedly recalled an event over and over and over again, little errors can accumulate. Over time, a memory for something that actually happened can morph into something else.
I like to say that memory is not as much like a photograph as it is like a painting. The painter might include some realistic details but there’s also going to be some distortions, and then there’s going to be some stuff that’s neither true nor false, but some kind of a reflection of the painter’s perspective and their imagination. And from the painter’s perspective, that’s an accurate portrait. In other words, whenever we’re talking about memory, I think you want to avoid thinking about true or false in the sense of assuming that everything has to be one way or another. It’s always going to be a complicated mix.
WL: Why can I remember some things very clearly from 30 years ago, but I can’t remember who came to Thanksgiving last year?
CR: The answer is that from 30 years ago, there are a lot of things that you don’t remember, but you’re not thinking about the things that you don’t remember, because you don’t remember them. So the things that you do remember stick out. I guarantee you, you have more things that you remember from, let’s say, 10 years ago than you do from 30 years ago.
Regarding the memories of recent events, sometimes what happens is you just need to be in the right context. Right now, you might not be able to think of who came to your house for Thanksgiving. But then maybe next Thanksgiving, last year’s guest list pops into your head. Or somebody says, “Oh, do you remember that Samantha and I came for Thanksgiving?” And then all of a sudden, you find it jogs your memory and you can pull up more details about it.
Moreover, the act of recalling the same memory in different contexts also leads to changes in that memory. I had a near-death experience while paddleboarding in rapids on a river. And it was a pretty terrible experience. But the interesting thing was that once I’d survived it, it became a funny story of a mishap. And this is a classic example of how sharing memories can transform them and transform your relationship with them. One important aspect of psychotherapy, in fact, is that it involves collaborating with someone else in viewing your past and any traumatic memories from a different perspective.
WL: Memory has been in the news lately because of some of President Biden’s gaffes, and you wrote an opinion piece about that for the New York Times. Can you shed some light on that issue?
CR: What people are calling Biden’s memory problems are really gaffes that have to do more with his ability to access information when he needs it. This is a very typical age-related issue. In general, this kind of absentmindedness, the feeling that a word is on the tip of your tongue but you can’t quite find it right now, is very normal with age. It is not a sign of reduced competence or reduced cognitive functioning. It is just something that happens as we get older.
And it happens because of changes in the prefrontal cortex and the efficiency with which it works. On average, those changes start around the age of 30, and some people experience it more than others. We’re more likely to be absentminded in the moment. And whatever we have encoded in our memories, we’re much more dependent on cues in the outside world to recall it. We have a harder time generating the memories on our own and are more likely to get stuck on the wrong memory.
WL: Do you have suggestions or tips for people about how to remember things they want to remember?
CR: When we’re talking about the more tedious things that you have to remember, the tip that I give people is to plant cues ahead of time. For example, yesterday, I spent two hours looking for my cell phone. I kept trying to remember what I had done with it. I eventually found it, but I had no memory of having put it down in the place where it was. If you have to work to reconstruct that memory of where you put it, then you’re starting off at a major disadvantage. On the other hand, if you plant clues, like making a specific point of noticing where you put down your phone in order to create a memory of putting it down, that can serve as a trigger to pull up the information later on.
In general, it’s important to realize that our memories are incomplete. And if that’s the case, what are the memories that you really want? What is the information that you want to have stick around? Because there’s no magic bullet to allow you to remember everything. But documenting or thinking of documenting something at the time can help ground you in the experience—for instance, thinking about what you’d write in your journal about the experience might focus you on the essentials of the event.
However, if you’re trying to document everything mindlessly by taking pictures, you might believe that you’re going to remember it better, but in fact, it can be quite the opposite—people might remember taking all the photos more than the experience itself. But if you look at the photos later, after you’ve posted a series of them on Instagram, say, and then you use it as a memory retrieval cue to pull up more details of what happened, the act of pulling up that memory will strengthen it and make it more accessible.
