This episode is an extended interview with Dr Charan Ranganath, director of the Memory and Plasticity Program and a Professor of Psychology and Neuroscience at the University of California at Davis. He’s also the author of the book, ‘Why we remember.' James Tytko started by asking him about his love of popular music...
Charan - Yes, music is a very big part of my life and, when I wrote this book, it was a very personal thing for me to be able to write something that both tracked the development of my own ideas, but also my life in this field of science. Some people who are personally attached to Proust or William James or these kinds of things that people often cite in their popular books on memory, for me, these are my touchstones, and it gave me a lot of happiness to be able to put Picasso, Akira Kurosawa, the Wu-Tang Clan in the same sentence.
James - Terrific. And, as I understand it, you've been looking at using music as part of your science from the very beginning.
Charan - Yeah, that's right. Music is very evocative for being able to put people in a mood. In our early research, when I was interested in the effect of emotion on thinking, actually we ended up using music to evoke memories and then hoping that the memories would actually affect people's mood. That was exactly what happened. So everything else in that experiment didn't work out, it all went pear shaped, but nonetheless, it worked out enough that I was able to publish it.
Really, the impact on me was much greater, I think, than the impact on the field in terms of my thinking about how deeply personal memory is. Actually, since writing the book, I've been just enormously touched by the fact that many times after I give public talks, or even with people like journalists for instance, they feel almost compelled to tell me their own memory stories.
James - Yeah, you mention one of the first things people always say to you as a memory expert is, why is my memory so poor? And it turns out, because I feel like that applies to me, you've got a positive message for me.
Charan - Don't get me wrong. I tell myself the same thing, 'Why am I so forgetful?' And I'm always forgetting things. It frustrates the heck out of me, and I'm sure this happens for many other memory researchers because many of us often study what we're not good at. You probably see this a lot in science. They call it 'me-search.'
If you actually quantify people's memory for at least meaningless, arbitrary details, which is a lot of what's happening in our daily lives: we don't remember the overwhelming majority of them after at least two days. In fact, the majority of our experiences within a day will be lost. That gives you an idea that we're being very unrealistic if we think that on average we're supposed to remember everything. I think the expectation should be that we're not supposed to remember things. Then the question is, why do we remember anything at all? Which is where the title of the book came from.
James - So there it is, that's what you're trying to achieve. You are trying to switch the focus from, kicking ourselves over forgetting our aunt's birthday and instead trying to appreciate the amazingness of why things stick in our brains at all. Let's talk a bit about that process. What parts of the brain are specifically engineered to help us with this memory formation process?
Charan - There are different levels of this question, because it's a very big question. A lot of the questions that are the simplest are actually the hardest to answer. As it turns out, I think many memory researchers would say that every area of the brain is involved in some kind of learning or memory. But in terms of what people would colloquially talk of as memory, we typically are thinking of episodic memory, which is my specialisation. It's this ability to be able to remember particular past events, be it where you put your keys, or be it things like your 16th birthday or something, right?
These are particular events that we want to be able to bring back to mind, and so that ability to be able to remember something that happened just once at a particular, unique place and time is dependent on the hippocampus. It's a brain area that's tucked deep inside the brain and it's actually evolutionarily fairly old. Reptiles have a rudimentary form of a hippocampus, fish have a rudimentary form of a hippocampus. I think what makes the human brain, or at least the primate brain, especially notable is that we have another area called the prefrontal cortex, and there are some parts of the prefrontal cortex that may be even uniquely human.
James - You describe it in the book as being like the CEO of the brain. What do you mean by that?
Charan - Yeah, so for a long time people thought that the prefrontal cortex didn't do anything or they didn't understand what it did, which is why frontal lobotomies were quite popular in the 1960s. It's not very clear that the prefrontal cortex is extraordinarily important and it's not important because it does any one thing. Allan Badley, among others, who's a great British psychologist, used the term central executive, which became popularised as executive function. It's an apt analogy because, essentially, you try to give an executive any kind of a real job like mopping the floors, doing accounting or something, good luck! They're not going to do it very well.
The job of an executive is not to do any one thing well, but rather to take a bird's eye view of all of the offices that are part of a bigger project, a bigger endeavour, and orient them towards a particular goal. As a result, if you lose the prefrontal cortex, which would be responsible for executive functions in the brain, you still have all the abilities to walk, to talk, to think, but you can't remember very well, you can't pay attention very well. Anything that you need to do that is based on your own goals, you lose that ability. So it's not about memory per se, but it's about using information in memory to guide what you do and to be able to focus what you do on your goals and be able to form memories for things that you're really focused on, which would be like what I call in the book 'learning with intention.'
James - To go a level deeper, in terms of the way we perceive the world, our sensory functions, how are they then translated into things we discard or things that lodge themselves in the brain? You draw the distinction, don't you, between the thinking and the remembering self.
Charan - This is actually paraphrased from the Nobel winning psychologist Daniel Kahneman. Danny talked about this idea that there's the experiencing self, which is the person who lives in the moment, and then there's what he called the remembering self, which is, essentially, after an event is over, it's the person that makes choices and decisions based on not what they experienced but what they remembered.
As an example, you might have had a holiday recently and you spent a long time in queues, whether it's in the airport where you spend a long time in the queue at baggage claim, then you find out some of your baggage is missing, blah, blah, blah. 20% of that time is spent relaxing, but a good amount of that time is actually spent doing things that are quite unpleasant. But the next time you're planning, you'll probably plan a holiday for that 20% of the time that was pleasant. You probably won't put much thought into the parts of the trip that were unpleasant. I know Kahneman argues that's very irrational, but I think the brain is designed that way for a reason. It's designed that way because it's about holding on to what's important and grabbing what is most useful to guide our future decisions.
Sometimes it's going to be things that are biologically important, things that give us pleasure, things that give us states of desire, or things that give us a sense of love or attachment. You can see basically during any of these kinds of experiences that there's these chemicals called neuromodulators that are released in the brain. Many of your listeners probably know about them, like serotonin, dopamine, norepinephrine. These chemicals do generally have a similar effect, which is they affect the way that you pay attention in the moment. They affect plasticity, meaning that they solidify these changes in the strength of connections between neurons, which are essentially the unit in the brain of computing particular things, whether it's perception or thought or memory.
James - And I know you've not necessarily written this book to dish out advice on how to improve our memory, but what are the things that hurt our ability to remember things? And am I right in thinking that the modern world has kind of supercharged these factors and made them more pronounced?
Charan - So, why don't we remember many things? The typical reason has to do with competition. If you have an experience that you formed a memory for, that's very distinctive, it just stands out relative to everything else. Those are the experiences that you're going to be able to capture the best. The modern world, I think, is not the problem in and of itself as much as our meeting the demands of the modern world, right?
For instance, in theory, my smartphone was supposed to make life easier and, instead, now anytime that I'm not doing anything, I feel this urge to check my phone. Whether it's an urge to check email or an urge to check text messages, thinking about what's happening on Facebook or whatever can take us away from the present moment. This isn't necessarily bad except the problem is, if my goal is to actually pay attention to and remember this conversation that you and I are having, then every time that I switch, even for a moment, in this thought process, I'm losing a little bit of executive resources just to switch over to this new thought that I have. And then I have to use executive function to pull back into the conversation.
There are actually memories that are formed at those points which we would call event boundaries. An event boundary could be even something as simple as my changing the topic of conversation to answering this question. Now I've changed the topic and now I have to say, 'wait, what were we talking about again?' I've now formed this new model of what's going on because I'm telling you something entirely new. But now I have to switch back and forth and that requires me to effortfully recall something from just a moment ago when I was talking to you. If we're not connecting those dots in the moment because we're constantly switching back and forth, what happens is that you have a bunch of fragments that are competing because it seems like, even though it should be one continuous conversation in your memories, you've encoded a bunch of things that are unrelated to each other.
James - Is memory something that needs to be trained to be maintained? We talked about how we outsource a lot of our tasks that we would've had to do ourselves to our phones, for example, storing appointment times or phone numbers or things. In the book, you talk about early man having this necessity to remember which fruit is poisonous or which body of water is crocodile infested. Do the different taxes of the modern world mean we are losing something compared to our ancestors?
Charan:
Yeah, I've heard this argument: you use it or you lose it and that memory is like a muscle or whatever. I don't adhere to that view and I've yet to see any compelling evidence for that view. I think most neuroscientists would agree that we are constantly learning. The problem is that sometimes that learning can mean that the plasticity that we have in the brain throughout our lifetime can mean we start to lose things that we've already learned if we are not careful. So what I would say is that it's not so much a use it or lose it thing, but are we using it the right way? Are we using it to remember what we want? Because if you can't remember everything, then the question is, okay, well does it matter?
I don't want to remember most things I've experienced, like anytime I get a temporary password and I have to enter it into my phone or my computer just long enough to reset to something meaningful, think about every one of those temporary passwords. It's a lifetime of junk that you never want to accumulate. Or cave person trying to figure out which fruits are poisonous and where the sabre tooth tigers are, their priorities are pretty clear. And the brain's biology is quite optimal for figuring this stuff out without actually a whole lot of pontificating. Then, there's things that you can see in many traditional cultures in terms of things like navigation abilities, and there's Polynesian cultures who have accomplished just extraordinary feats in being able to navigate just by looking at the stars and so forth.
So there are all these abilities that are out there, but it's a matter of finding the right skills and adopting the right practices for remembering what you need to remember and dumping the rest.
James - How is the way our memory works, as you've described it, the episodic nature of it, used against us in certain cases. I'm thinking about this idea of nostalgia and rose tinted glasses. It's probably best if we start by asking why that happens. What is that phenomenon?
Charan - I was just talking to somebody who studied nostalgia and history and basically one of the things that people always tell her is, 'nostalgia ain't what it used to be!' And I think that captures the slippery nature of nostalgia. But the bottom line is that, in our modern day, we tend to think of nostalgia in a positive way. It can be enormously good for mental health to think of times in our life that were very positive and, on average, people have a positive memory bias, meaning that they remember positive events better than negative or bland events. As a result, it can give us good feelings in the present to think about these positive experiences, except that sometimes what can happen is that people take the wrong interpretation from that.
The wrong interpretation could be things used to be so great, whether it's for me personally, when I was young, everything was so rosy and life was good and I was free and now I'm not able to hang out, you know, after two drinks I get a hangover, constantly having to worry about falling, or whatever it is, right? Or, in the case of national or collective memory, there's things like, 'Oh, our country used to be great and now it's terrible. What happened?' 'Oh, it must've been these outside forces and that nostalgia can get weaponized.' I call it toxic nostalgia and it reflects a memory bias.
Right now, there's a lot of nostalgia for how America used to be great and how it was not great. Some of this concerns, for instance, the loss of industrialisation. I lived through the seventies and there was a big loss of industrialisation at that point. Instead of China, people were very worried about Japan and so forth. These things are not new to this time. Back in the seventies, there was nostalgia for the fifties. So I find it very difficult to accept that people are nostalgic about the eighties and nineties now. It doesn't feel like it was that long ago for me, but that positive memory bias can lead you to adopt an incorrect view of how things were relative to how things are now.
James - While I've got you, a memory expert, I thought it was very pertinent to touch on one of the issues that's going to be one of the defining ones of the next generation, related to memory. And that's how it changes as we age. It's estimated that one in three of us will go on to develop dementia. With an ageing population, perhaps because of medical advances in so many other fields, this one is becoming a more prominent concern and there's a lot of resources and scientific interest in finding the causes and potential cures for it. How does our memory change as we age and I suppose, how doesn't it? What are the misconceptions?
Charan - I think one of the big misconceptions, and especially recent research has really revealed this misconception, is that everybody gets worse as they get older. What we're finding is, if you look at longitudinal studies, meaning studies that follow the same person over say 10 years, what you find is that there's enormous variability. Some people will show a steep decline and some people will show virtually no change in cognition for a very long time. You can see this in many people who are in their eighties or even higher, who are just exceptionally with it and have great memory, and so I think this is an important point to make, that knowing someone's age in and of itself doesn't tell you a whole lot.
The second point is that if you do follow the averages, though, performance on some kinds of memory gets worse. So what I mean by this is your knowledge about the world tends to stick around and is quite stable and can even improve over time. And your old memories, the ones that you've carried from your younger days, tend to stick around. But basically the most common change that happens is that you are more forgetful often because you are losing this executive function. This is very common, actually. We think it starts after the age of 30, which is quite shocking, but it's a decline that happens throughout adulthood. You'd be hard pressed to find an older person who feels like they find words that come to mind, that they're not any more distractible or they're not any more absent-minded than they used to be 20 years earlier. That's largely due to changes in the prefrontal cortex, both structurally, but also in terms of chemical changes that can happen and so forth. That is a big part of it.
And then of course there are other changes that can happen to the hippocampus, like we talked about. Sometimes those changes are basically a very early development of Alzheimer's disease, but that's where the variability really kicks in. I think there is some controversy, but I think one compelling line of thinking is that there's a point over normal age-related development where you can get a forking off into this pathway towards Alzheimer's or other neurodegenerative diseases. These diseases tend to be caused by proteins that misbehave. I was just talking to somebody who studies longevity, for instance, and these things are kind of inevitable at some point. But the question is, when does that happen? And it's enormously variable.
James - A certain person whose memory has been of particular interest to the press of late, for a number of reasons, is Joe Biden. So there was a report written about the fact he couldn't recall necessarily the exact years he was vice president or the details of when his late son died. Being president, there are a whole lot of interruptions to the way our memory works as we were describing earlier which could account for some of that, but people have also pointed to his age.
Charan - People have been talking about Biden's age for a while in the US and, to be clear, Trump is not much younger. I believe he's 77 and Biden's 81, if memory serves. Within the realm of age related changes and thinking and memory. That's a negligible difference really. They're both known for memory lapses, but the reason this came up, especially for Biden, was that there was a special counsel that was investigating Biden for some alleged issues, and they didn't turn up any evidence in this investigation that was sufficient to suggest that he had committed any wrongdoing. But part of the report contained a statement that effectively they couldn't prosecute him because people would see him as an elderly man with poor memory. And this really struck me because, as a memory researcher, I want to know what they mean by this.
So I looked at the report and, at least the cases that I saw that were used as evidence for poor memory, were either cases which were not in line with what the implication was, or there were cases where it was not even a memory thing at all. What I mean by this is that, as I mentioned earlier, as we get older, it's often not a matter of having no ability to form memories, but at least in healthy ageing, it's usually a case of not being able to find the information that you're looking for when you need it.
One of the things that they talked about in special counsel's report, under this questioning, while there was all this stuff happening in Israel, he was being asked about the year that his son died, and he said he couldn't remember the right year. That might seem, well, 'how do you not remember that?' But it's not that he doesn't remember any experiences from the time that his son died or that he doesn't remember that his son died. It's just he wasn't able to pull up this one detail. I think we've all actually had these experiences where we couldn't pull up the right detail when we needed. What I would be worried about is if he couldn't remember that something happened as opposed to some detail about what happened. Then, there are other things like his notable gaffes, so to speak, where he was saying, and I think this really hurt him, in his press conference right after these allegations by special counsel, he inadvertently referred to the president of Egypt as the president of Mexico. Now, I think it's fair to give the president the benefit of the doubt that he knows the difference between Mexico and Egypt. Likewise, Donald Trump had a major gaffe where he accidentally confused Nikki Haley, who's a Republican opponent, with Nancy Pelosi, who's a democrat who's extremely unpopular amongst Republicans in the US and he clearly knows the difference between the two people, I would hope. Again, these are things where it's not that they have a memory problem at all, it's that they pulled out the wrong name or the wrong word at a given time and they were slow to catch the error, which is typical of healthy ageing.
Now it's fair to ask, so you have changes in frontal function as you get older, does that affect your ability to do the job? I think there are memory issues that are relevant to doing the job, but there are also memory issues that can be compensated for by assistants and by a phone, for instance. I think the question is, memory is one ability, but that's episodic memory too. There's knowledge about the relevant facts, knowledge about foreign countries. If you're running the United States or running a powerful country like the UK, you have to know about countries all over the world. You have to know about laws relevant to the economy. You have to be thinking about military and diplomatic priorities. There's a lot of knowledge that needs to be there, and I think we don't place enough importance on the fact that people with a lot of years have a lot of knowledge and it's quite stable over time.
James - I suppose it's nice that these gaffes happen to the best of us, or the worst of us depending on where you stand on this. Charan, thank you so much for your insights. It's been an absolute pleasure.
Charan - Thank you. Fan of the show, and I'm happy to be doing this.
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