Charan Ranganath: Unlocking the Power of Memory

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0:48I'm Guy Kawasaki and this is Remarkable People. As you've now heard for about 250 times, we are on a mission to make you remarkable. Today's remarkable guest is Dr. Sharon Ranganath. He's a distinguished professor of psychology and neuroscience at UC Davis, and he's the director of the Dynamic Memory Lab. Sharon has dedicated over two decades to exploring the intricacies of human memory, and he's employed a variety of methods from brain imaging to computational modeling. His book, Why We Remember, Unlocking Memory's Power to Hold on to What Matters, offers a remarkable perspective on memory. It not only demystifies the common frustrations of forgetting, but also highlights the critical role memory plays in our daily lives, from learning and decision-making to managing trauma and fostering healing.

1:50The book challenges the traditional understanding of memory. It argues that our brains are not designed to retain every minute detail. Instead, they extract meaningful insights from our experiences to better navigate the present and prepare for the future. I'm Guy Kawasaki. This is Remarkable People. And now, here's the remarkable Sharon Ranganath. How many guitars do you have? I see guitars in this picture. so if memory serves there's about wait wait what do you mean if memory serves you're the memory guy i know i know well okay so there's some guitars that are basically dismantled or in various states of non-playability but if i include the ones that just need minor repairs or actually okay.

2:41That would be three acoustic guitars, one bass, and then another two baritone guitars, and then I think three electrics. I thought this was just going to be a multiple choice question. It wasn't going to be an essay. Yeah, I know. It's one of these things. So people who play guitar will understand. So I always skimped and skimped when I was a grad student and because I played music then and it played in bands but now that i can i collect them but i use them because it's like every guitar brings out different songs from you they feel different in your hands so it's not so much the sound of the guitar with electric it's like you can make it sound like anything if you know what you're doing but well it's really more that the feel of it the feel of different guitars brings out different playing in you to give you a parallel question which you could probably relate to because you mentioned surfing in your book.

3:41If you ask me how many surfboards do you have, I would have to give you an essay answer too. Depends on how you define I have. Is it I have that I use or I have as trophies on the wall or I have with my kids that we share? It's not as simple as six acoustics and three bass, but anyway. way yeah that's right you need a what a thruster you need a longboard you need so much stuff how is your surfing have you continued no part of it is that it's i'm a lousy swimmer part of it is that it's i'm out of shape part of it's that i'm very far away oh let's blame it on the fact that i'm far away from the shore yeah so since i wrote the book and finished it i have not been surfing Where do you live?

4:28I live in Davis, California. So that's pretty far. Yeah, it's not as bad as you might think. If I went to Bolinas, it's probably about a two, two and a half hour drive, two and a half hours, let's say. Parking there is supposedly pretty bad, but it's cold. It's cold water. Are you in Hawaii? No, I'm in Santa Cruz, California or Watsonville, California. Oh, you're in Santa Cruz. Okay. Oh, yeah. So do you have any, you have a connection with Hawaii? I'm sorry. I don't know that. Yes, I was born and raised in Hawaii, but I never surfed while I was growing up. And I came to California and I started at age 60.

5:05So you're not 60. So, you know, you can take like probably, how old are you? 40? Wait, did you say age 16? 60. 6-0. 6-0? Oh my God, you look great. That's the beauty of high-res cameras and AI. yeah i'm 50 i just turned 53 last week so i gotta tell you a short story to get this rolling okay i'm from hawaii my family and i we go to hawaii probably every year once a year and when you go to hawaii you have the stereotypical great surfing sessions you go to the luau you go to all the great restaurants and all that stuff what the hawaii visitors bureau wants you to know But one year we stayed in a place called Hawaii Kai, which is about 15 miles from Waikiki.

5:56And on New Year's Eve, the guy who owned the house took us in this powerboat to watch the fireworks on New Year's Eve from the water. And little did we know that a small craft warning happened while we were out there. And so going there was fine, but coming back got really rough. And people started throwing up and it was like awful. They thought they were going to die. And, you know, they're like really throwing up over the side and all going crazy. And I tell you this story because now when we talk about Hawaii, we don't talk about the great food, the great surfing, the great. We talk about the trip from hell.

6:38OK, so now you're the memory guy. Why do we remember what we remember? Why do we focus on something so bad at the time as like now brings us great joy? Yeah, I have a few stories like that in my book too, which is stories of things where everything went totally wrong. And, you know, I always like to say that if something bad happens to you, it's not worth it unless there's a good story you get out of it. I suspect you live by similar philosophy in life. But I think the two things that come from these experiences are, one is they're emotional, and our emotionally intense experiences are going to be the ones that we remember.

7:24There are certain chemicals in the brain that are released during intensely emotional experiences, times where we're scared or times where we're in moments of desire or attachment, stress. And so those chemicals, we call them neuromodulators. They actually promote plasticity and enable memories to stick around and be more resilient. So that's part of it. I think another part of it is that you have something that's memorable and emotional and you want to share it with people. So if it's not something truly traumatic that's associated with shame, you probably will share those experiences and sometimes start commiserating about them.

8:05But then they can also be used as almost like a little brag that you survived it. As that becomes now, every time you tell that story, it becomes more memorable. It actually, you strengthen that memory itself just by virtue of retrieving it over and over again. Now, you might even embellish it more and more. Like, I imagine you have a long version of the story that you tell people after a couple of years or something. And the long version, I'm sure there's a lot of embellishments that come into it. And the more times you embellish, the more of those details can become incorporated in the memory, too.

8:40Those experiences that are emotionally intense, but we get a good story out of it. Sometimes they become at some point more of a story than they are a memory. It started off as rough seas and it's already progressed to small craft warning and next step is hurricane. I can see the slope of this line already. It's like that movie, A Perfect Storm. I'm picturing Mark Wahlberg on the boat with you. I want the rock to play me. You can play you, man. So you kind of answered why we remember what we remember. But now, why do we forget what we forget? So forgettable experiences are ones in which the memories are just like every other experience we have, right?

9:30What I mean by this is that memories in the brain compete with each other. And many times when we forget, it's because these memories are drowned out by other memories that overlap with them and are similar to them. And there's nothing remarkable about them. There's nothing emotionally intense. There's nothing important relative to our goals. There's no surprises involved. And so all those factors can lead us to essentially forget about them. And that's a good thing, right? Think of all the temporary passwords, the people who you meet in passing who you'll never meet again. No offense, but it's like you meet a TSA agent while you're going through.

10:11You're nice to them. They have one line, but you don't really need to carry that information with you. That's what I'm talking about. And those memories, it's hard to reverse engineer why did you forget them, right? And maybe there's something in there so that if you met that TSA agent, again, it would be a little bit easier to memorize their name and remember their face the second time around. I don't know. Many of those things we just don't know. But basically, the kinds of factors that make something forgettable are unimportance, familiarity, like they're just not novel, predictable, and emotionally bland.

10:50It sounds like I'm bringing back TSA trauma to you, but okay. Well, I just got back from Seattle a couple of days ago. but it wasn't a traumatic one it was actually a nice experience but i could not remember the tsa agents that i dealt with for the life of me actually i do there was a colorful so this is a great example the one thing i remember was there was an extremely colorful guy who was near the conveyor belt and he just kept saying okay don't forget to put this inside put your electronics in a separate crate, but he was doing it in this way that was almost like theatrical. And it just struck me.

11:33That's what I remember from my TSA experience. And if it wasn't for that guy, I would not have any memory of it, I'm sure. It's like when you see a traffic cop having really lots of fun, right? Exactly. Yeah, exactly. Explain to me, are things like remembered and then forgotten? Or is it, what's sort of the baseline? Do you remember and then you forget or you forget and then you have to recall? What's going on there? Are we predisposed to forget or predisposed to remember? This is a very hard question to answer because it depends on what it is we're talking about. So what I would say is on average, we're predisposed to forget.

12:18And what I mean by this is research shows that if you give people like a bunch of meaningless information that they have to memorize, about little less than two-thirds of it will be forgotten by the next day. How that translates, though, into real-world events is a little bit harder to say, but on average, I would argue that, yeah, we forget more. And here's one way in which we can answer this question, right? Later on, you say, hey, do you remember that really amazing interview you did with this memory researcher. So then you go, oh yeah. And you describe it and you can describe that event in like about two minutes.

12:58But then at that point, you're going to run out of details to talk about, right? So it's not a literal replay of however long we're going to spend talking. It's really a reduced version of that. And there's a lot of details, exact words that I'm saying, exact things that are going on in the background, sentences, even several minutes that are just going to be dropped. So when I'm asked about this interview in a year, I'm going to say, oh, that's the guy with all the guitars. Right? Right? And then you'll go, what was he talking about again? I can't remember. Oh, yes. That's what we talked about.

13:36We talked about forgetting. Yeah. But when people ask you about interviewing with me, you're going to say, oh, that's the guy who sent me the socks. And you're not going to remember anything else. That's exactly right. I have already forgotten many of the podcast interviews that I've had, but I will not forget the man who sent me those great socks. And the microphone, too. I don't care what it takes to stand out, as long as I do. No, no, this has been a lot of fun already. It's a very memorable interview. Much more memorable than some other ones. Yeah, you say that to all the podcasters. But anyway, so I mean it.

14:23On a slightly more serious topic, based on your book, I must say that I am not too confident in witness testimony. testimony. So when you read about criminal cases and it's 10 years old and they have eyewitnesses, it's hard to have faith in what they're saying, isn't it? I think it depends. What I hope to convey in the book was that you can't look at any of these things in memory as an all or none phenomenon. In the case of eyewitness testimony, it's not like I'm telling people, oh, ignore it. It's all unreliable. Nor would I say that it's like you should just blindly trust a confident witness.

15:08Let's say if you and I became friends, and hopefully we will because I need some serious surf instruction. And I have a good man to do it. So let's say I go visit you in Santa Cruz a bunch of times, right? We start hanging out. We become pals. I teach you a little guitar. You teach me a little surfing. And so next thing you no, I see you like rob a bank or something like that. So the policeman said, okay, so who robbed the bank? I'll say it was Guy Kawasaki. And I will be very confident and I'll be pretty accurate because I know you. And so I have a very good memory of who you are. I'm hopefully not going to mistake you for somebody who looks like you, right?

15:49But on the other hand, if it were somebody who I didn't know, and let's say they were from, my wife actually says this to me that I cannot tell faces apart. She'll say this about anybody. If you look at the literature, for instance, there's a big factor called the other race bias, where essentially people have a harder time recognizing faces of people of other races. And it's not necessarily a prejudice thing. It can be just a lack of exposure to people of other races. It's also the fact that I think there's data to suggest that people, when they look at someone from another race, they actually don't pay attention to what makes them unique as much as the factors that help them identify the race.

16:33Whereas when they look at people of their own race, they're able to actually see them as a unique face, which is sad, but also fascinating and revealing. So let's say somebody is trying to do an other race identification and it's very quick. They just get one flash. And then let's say they look at the mugshot and then they're being asked to look at it again and again and again. And then at some point, third time around, they're like, I think that's it. So then they do another lineup. They're like, oh, I think that's it. And then they really, the third time around, they're really sure. At that point, that's a highly unreliable testimony because people can essentially create a memory for seeing this person rob the bank when actually they just saw this person in the mugshot book, and they may have looked a little bit like the person who robbed the bank.

17:24And as they look at it more and more, they become more and more confident. So there's a case like this in literature that I describe in the book. And in fact, there's many other cases out there that I did not describe in the book, but this is a remarkably common thing. And you'll even see this with AI face recognition systems, that they will also have these biases, especially with people of color. And the reason the AI systems have this problem is because they're using data curated by humans and the internet has these biases baked in. So it's an issue period when it comes to face recognition of strangers.

17:59There's more to it. I could go on and on and on, but that's just one example. You dedicate quite a bit of space to the creation of false memories. And I got the impression that in the hands of a skilled or skillful or manipulative person, that person can create false memories in people without too much difficulty. Did I get that right? I would say that we don't know why, but some people seem to be more susceptible than other people. There does seem to be some evidence that age and so children and the elderly are a little bit more susceptible to false memory creation. There's other factors like if you're under the influence of alcohol, if you're just tired and stressed out, all these things that reduce your ability to check yourself would be the factors that predispose you.

18:49Under an ideal circumstance, no, many people would not be susceptible to having an entirely false memory created. But I would argue that most people are susceptible to having their memory corrupted. And what I mean by that is, is that maybe you could ask me a question about a crime and you give me a leading question. When you saw this person rob the bank, were they in a blind rage? And let's say they just seemed a little bit, you know, you saw someone and they're just walking into the bank and they just look a little, they're frowning or something like that. You might now remember it more like they were really ready to go off and they're unhinged.

19:27And that's the power of imagination. Because when we remember the past, we get all these little bits and pieces, but then we generate a story. And that story reflects our beliefs in the present. Aren't you telling me that a skillful detective or a skillful prosecutor or a skillful criminal attorney can use these things to their advantage? I would argue that they do. I wouldn't necessarily say that it's intentional to create a false memory. But I think a good defense or prosecuting attorney will want to manipulate their witnesses to say what will be needed to convince a jury, right? But I think during the questioning, I mean, there's a technique that I talk about in the book called the read technique, and it's part of a standard manual for interrogation.

20:19And it contains basically the recipe for getting people to confess to crimes that they never even committed. It's definitely those kinds of questioning approaches that can lead people to get severe distortions in their memory. But not everybody uses those techniques. I don't, in fact, know how many people use those techniques, but it is out there for sure that somebody can. And keep in mind, by the way, this is not just limited to prosecutors. So one of the things I talk about in the book is an example of how George Bush Jr. was going up in a primary against John McCain. And so his campaign started doing these phone polls where they would call up people at their homes and say, hey, do you remember when John McCain said this?

21:08What do you think of it? And they implanted things in the questions that weren't true. And so what happened is that people who did the polls were more likely to think it was true. And so they spread this false information about John McCain and had to do his tax policies and this incredibly racist story of him fathering a black child illegitimately. And these stories ended up spreading just because they were in the question that was being asked in this poll. That wasn't even studied by memory researchers until years later. I suspect that in the research community, we're catching up to where people are actually using these techniques already in the real world.

21:50You also mentioned a positive sense of that quizzes can help you learn as opposed to just help you test, right? This is the same concept. Absolutely. If you're trying to say, learn a new language, for instance, or even memorize someone's name, the intuition would be, oh, I need to study it. I need to just say it over and over in my mind say the name, or if I'm trying to learn a word, I can just memorize the Spanish word just by saying it over and over again, like a palabra, which is Spanish for word, actually. And that's not true. The better way is actually to test yourself. And one of the coolest findings out there is if I test myself on a word or a name before I even get it, testing myself even before I know the answer can actually help me remember it better.

22:41And so we have a computer model of how this works. And what happens in the computer model is when you have some degree of error in the testing, that's when you really get some benefit. Because then what happens is the brain can suppress the wrong answer, which helps the right answer pop out more in memory. Wait, let me get this straight. So you're saying if you're trying to learn a new subject, You take a quiz before you know anything about it to prep you? Yeah. Wow. Now, what I would do is prep on each thing that you're trying to learn, though, but do the prep test. You don't want to wait till the end after you spent an hour studying.

23:20And then give you, I mean, you basically don't want to do it like give yourself a quiz on the entire thing and then, you know, an hour later, come back to it. You want to get some feedback fairly immediately. This is an eerie coincidence, but Madison and I are just about to release a book called Think Remarkable. And this is the Remarkable People podcast. So we have a lot of knowledge about how people can become remarkable. And we're also creating a course with Canva about how to be remarkable. And the people who design the course, they have quizzes inside each section, really simultaneous with actually presenting the information.

24:01And they said, yeah, these quizzes help people learn. I said, how can they help people learn? They don't know the answer yet. And then bada bing, bada bang. One week later, I'm hearing from a scholar that, yes, it's true. There you go. God works in strange ways. Yeah, that's exactly right. I see in your book and many other books, they're always talking about MRIs, right? So they show a person this and they look at the MRI and they say, okay, this is where the prefrontal cortex spiked and this proves that and that. I mean, is this all bullshit? I mean, tell me, everybody's going to an MRI and they're proving that this does that.

24:43You look at an image of this, it spikes this. Everything is an MRI. Is an MRI so reliable that I could show the MRI result to a scientist and the scientist could say, oh, I can tell you what caused that spike as opposed to show the person this and then prove that the MRI did it. Is MRI predictive? So you're actually asking me the method that I've used in my research for the past 25 years. Is it all bullshit? You should be able to defend it. Oh, no, you're absolutely right. Right. No, actually, the question is very astute. Can you just look at an MRI scan and can it be predictive? And the answer is, in some circumstances, yes.

25:28For instance, what people are starting to do is to use machine learning techniques where if somebody is watching a movie or even if somebody is remembering a movie, you can train computer models that relate the brain activity to the things that people are seeing and thinking about and so forth. And then in theory, you could present new things to the person and be able to generate a prediction of what it is they're thinking about, what it is they're remembering. Now, that requires a lot of data that may need to be person-specific. And right now we're still in the stone age of doing that for anything that's remotely interesting, but it can be predictive.

26:10A lot of the work that I talk about in the book, though, is more of an average of people, right? And this is a lot of the psychology and the neuroscience of everything. The neuroscience of everything is averaging across people and across animals and so forth. And so we don't yet have a great idea of what makes you different from me. And that is something I think that's the big gaping hole in our research. And then sometimes people do experiments and they're just don't have the richness to be able to do what you said, which is to predict what you're going to do. But I think we can do it. And that's one of the goals that I have in my research for the next few years.

26:53We're developing computer models of memory and we are using machine learning tools in our MRI research. And so that would be the hope. Let me just add, I know I keep giving you these long answers, but I should just add, MRI is just one tool. We're measuring blood flow in the brain, which is very slow. There's other tools like where we can record directly from the brain in patients who have epilepsy, for instance, they stick electrodes in their brains for surgery, where we can read out data in the millisecond scale. And that's the timescale in which brain activity really happens. And so I think in an ideal world, we would be able to do that in general.

27:32So MRI is one technique. It's very crude, but it can be very powerful in the right circumstances. Please don't take this personally because quite frankly, nonfiction book writers, business book writers like me, we have no proof of what we say is true either. So don't sweat that. No, no, I really am not. I was giving you a hard time. But can I just one more detail? So I have had something called Meniere's disease, which is deafness, tinnitus, and vertigo. And when you first try to get diagnosed, they stick you in an MRI. And this MRI is this thing where you're in this huge thing and you're in this little tunnel.

28:14And it sounds like a jackhammer is going off in your head. Is that the kind of MRI you're saying that we show people movies and we measure their MRIs? They're sitting in the middle of this thing with their jackhammer in their head watching the movie. Is that what you're telling me? It's remarkable. Yes. Actually, every kind of scan we do, let's say if I want to get a picture of the structure of your brain, or I want to look at the white matter in your brain, or I want to be able to measure fluctuations of brain activity, they all involve different kinds of what you call pulse sequences, which are different ways of using the magnets to measure things in the brain.

28:50and I have had people in my lab who've been scanned so many times they actually can tell what it is we're scanning based on the unique sounds of the pulse sequence so how do we do experiments is a great you really got I gotta say these are remarkable questions I never get these questions so it's great so when people are lying in an MRI scanner they actually look up and there's a little mirror and then they can see in the mirror outside of the magnet we have a video screen and the video screen will play the movie. And they have these noise canceling earbuds that we put in and we put like earplugs around them to keep them insulated from the sound of the magnet.