Short Wave - 'Stealing The Past': A Spat Between Twins Leads To A Theory Of Disputed Memories

Episode Date: May 6, 2024

It's not unusual for siblings to quibble over ownership of something — a cherished toy, a coveted seat in the car — or whose fault something is. If you're Mercedes Sheen, you not only spent your childhood squabbling with your sister over your memories, you then turn it into your research career. Mercedes studies disputed memories, where it's unclear who an event happened to. It turns out these memories can tell us a lot about people — they tend to be self-aggrandizing — and how the human brain remembers things.Check out more of NPR's series on the Science of Siblings.Curious about more science about memories? Email us at [e-mail] pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, shortwavers, Emily Kwong here. And riding shotgun with me today is our old pal and former shortwave editor, Gabriel Spitzer. Gabe, welcome back. Thanks, Emily. I am happy to be back. All right. Well, Gabriel, what is the news today?

What do you got for us? Well, I and all of my colleagues on the science desk have been working on stories about the science of siblings. So what I'm bringing you today has to do with siblings and how they remember. remember the old days. You know what I mean? Like, you have a sister, right? I do. Yes. I call her my best friend. And, and, um, she used to call me enemy, oddly. She couldn't pronounce my name. Enemy instead of Emily. Funny, funny how Emily became enemy, huh? What's her name? Amanda. Amanda. Okay. Have you and Amanda ever, like, disagreed about a childhood memory? I don't know. Maybe you, one of you remembers and the other one doesn't? Oh, yeah. There is a memory. Okay.

There was this time in our childhood home. There was some housework being done on the attic. And I wanted to go up there to explore, even though I'd been told not to. But no one had told me why. Okay. So I go upstairs. And in Amanda's memory of the event, she followed me up there and witnessed as I fell through the, like, plaster drywall ceiling situation and was like hanging upside down from the ceiling in the living room. caught it by my legs. It was very mission impossible. But in my memory, Amanda, was not even there.

And she just, like, heard the big crash. And we argue about it all the time. This is something that a lot of siblings go through. You might be, like, talking over the old days or whatever. And you'd find out that your memories don't totally line up. And so I wanted to introduce you to this woman who has had some disagreements with her identical twin sister. The woman's name is Mercedes Sheen. The best example is our first kiss. My first kiss would I perceive to be my first kiss. And I remember my twin Macaulay would say, hey, no, no, no, that happened to me. That happened to me.

We both felt that it was 100% us when the event could only have happened to one of us. This used to drive her absolutely up the wall. I bet. Like laying claim to the same first kiss memory? Exactly. You know, sometimes it cut kind of deep. You know, our memories tie us to our personal past are this is us. And when someone kind of steals, in fact, my thesis,

was called stealing the past because it really feels like someone's taking your history from you. One could say that I took my arguments with my twin to a great extent by doing a PhD on it. The ultimate twin vengeance. But seriously, it is a kind of identity theft when you claim someone's memory as your own. But now I'm wondering, like, how do you even know whose memory it is as if you're both confused? Right, right. And is it always the case that one is right and one is wrong or, you know, is there shades of gray here? So these days, Mercedes-Sheen's a professor of second.

at Harriet Watt University in Dubai. And for that PhD thesis, she talked about, she designed this whole series of experiments with identical twins to see if other pairs had the same kind of arguments that Mercedes and Michaela had. And this would wind up leading to a whole new framework for thinking about these kinds of memories that's now, you know, widely used in the field.

We kind of created this new false memory phenomenon. It had never been discovered before or never been named as such. So we called it disputed memories. Disputed like disputed ownership of the memory, as in which twin did it happen to? Today on the show, what happens when siblings disagree about who owns their shared past? And what that can tell us about how the human brain remembers? You're listening to Shortwave, the science podcast from NPR. Okay, Gabriel Spitzer, you just introduced us to psychologist Mercedes Sheen.

and her kind of analysis of this concept of disputed memories. So she mentioned one example of disputed memory for her was her first kiss in dispute with her twin sister. Tell me you got her to spill the tea on this memory. She shared it very willingly. I think she's still annoyed. So we were at summer camp in Canada in New Brunswick. We were walking up the hill. And this guy called Jeff Levitt, who was the camp catch, the most gorgeous,

guy at camp, he pulled me aside and pulled me into a bush and kissed me on the lips, like very briefly. Oh, all of a sudden. All right. Did she like that? Yeah, she was into it. And this was a really big deal for her. It was her first kiss.

And yet, she did not tell Michaela at first. When I told her, like, six months later, she said, that was me. That was me. And I said, no, it wasn't. It was me. It actually makes me worry that Jeff was kissing both twins. Uh-huh. I wondered the same thing.

Mercedes said that they actually stayed friends with Jeff for years afterwards and that he only remembers smooching one of them. Okay, well, which one? He asked him and he said, I can't remember. And one thing that is so wild about this, Emily, is that both of them were so sure. So you still don't agree on whose memory it is? No. How confident are you that it's yours? 100%.

And how about your sister? 100%. It's kind of bizarre to think that, you know, you have such a strong memory and like the sounds, it smells. And to think that it didn't happen, it kind of makes you think, well, wow, so what is real? Well, here's the thing. As I always kind of knew memories were subjective, but this is like a whole different realm. This is like contested reality, you know?

Right. That's exactly it. And because our memories are such like an intimate part of our identity, we can get really kind of like defensive about it and very attached to our own way of thinking. about it. And so, you know, Mercedes, when she was in graduate school and looking to do her PhD, she wound up going out to lunch with this researcher named David Rubin. She mentioned to him that she was an identical twin, and he was like, oh, do you have any, like, weird memory things between twins? And she said, aha, as a matter of fact, I do. So what she did was first she recruited a bunch of identical twins. And she figured out different ways to ask them, do you have any memories that you

don't agree whose it is. I used, I think, 20 or 30 keywords that sort of would cue everyday experiences like birthday, McDonald's, road trip. And just by asking them both to come up with their memory in response to those cue words, they just happened spontaneously. So once they found a disputed memory, the researchers would ask all these detailed questions like, what do you remember seeing? What do you remember hearing? Do you see the memory from your own point of view or in observers? And they found that In most cases, both twins were equally credible, even though the event could only have happened to one of them. I'm just imagining all these twins leaving the research lab and fighting with each other. Like, no, you messed up the study. No, you messed up the study.

Emily, you're not wrong. It's really interesting the way the arguments came out, and they all had the same types of arguments that I had had with my twin. So I was like, no, you always do this. You steal my memories. So how common is this among twins? And also just like among siblings? Sure. Well, the effect. was strongest between identical twins like Mercedes and MacIla. But Mercedes did experiments later that showed that fraternal twins experienced this too, to a lesser extent, as do non-twin same-sex siblings like you and your sister Amanda. And another thing that they found was that disputed

memories tend to be self-aggrandizing. Like they paint the rememberer in a positive light or as the main character of the story. Our memories are selective. Our memories are not a file that we pick out from our brain, they're reconstruction. I'm interested in this idea. Can you say more like our memory isn't a file we pick out from our brain? What's she mean by that? Yeah, this idea takes a little getting used to, I think. So I talked to another psychologist named Charles Ferniho at Durham University in the UK. And he said making long-term memories is like a really complicated construction project.

My dad used to say to me, if you've got a machine with many moving parts, like a car or whatever, there's just so many more ways it can go wrong. And memory is one of those machines with many moving parts. But what kind of moving parts are we talking about? Well, Charles says that memories are made up of different kinds of information. There's like what actually happened, and then there's all your subjective sensory information, like what you saw, what you heard. And then there's something called semantic knowledge, meaning knowledge of how the world works.

And all these things are run by different neural networks in the brain. It takes all those different kinds of information, spread across all those different bits of the brain, and it puts them together right here, right now, when you're being asked to remember. It reconstructs a version of the past according to the demands of the present. Most of this is completely unconscious, but there's this tendency,

depending on what the context is that you're remembering the thing in. If it would benefit you to remember it a certain way, then that's the shape the memory often takes. We are such unreliable narrators. Indeed. And I can now see why on a neurological level the brain might get it wrong sometimes

if you're saying this is all happening through different neural networks. It's almost like not our fault. It is very much about the architecture of our brain, and it's not your fault. I mean, each time you go through the process when your brain's whole like Rube Goldberg machine gets going and you reconstruct a memory, it's a different self that's remembering each time. So the result could be a little different. So if we tend to remember things incorrectly or in a way that suits our best interest and we can be so certain and our minds can't tell the difference, I mean, it just makes me think about all the controversy over like, courtroom testimony, right? And how reliable people's memories actually are, even if they're

completely sincere that that is what they remember, they could be totally wrong. That is a really apt comparison, Emily. And it's actually one of the reasons why Mercedes work is so important. You think about eyewitness testimony, they're the most convincing in court. You say, I remember it. I remember looking at his hair. I remember seeing it. And they're often incorrect. Right. These sensory details are what crop up, even if they're not true. Exactly. And there's decades of research behind this now. And these are the qualities that twins often use to say, this is my memory. I remember ice cream melting in my hair. I remember the humiliation. I remember the sound it made or the smell of fire burning.

And all these qualities that are used and I would as testimony are also used between twins when they want to argue about their memories. That's hilarious. It's also very unnerving. Just like, you know, human to human. Right. I mean, it's like Mercedes said earlier, you know, what is real? And really, it goes even further through the looking glass. I did a study once on the confusion between real and dreamt experiences. And actually, people can sometimes think you dream something because you have so much imagery involved with dreams, you can actually remember it as a real event. So given all of this, like, what can we hold on to when it comes to memory? I think the first step is kind of letting go of this idea that memory is just like, you know, pulling a file from an archive. That researcher from the UK, Charles Ferniehobe at this

point. People often, including me, get really confused about whether they're remembering an event or whether they're remembering seeing a photograph of an event. And that's the problem with memory. We're never remembering the thing pure and simple. We're always remembering a version of a version. It's always a memory of a memory. Everyone misremembers. And we all should stand to remember that. One nice thing is that, like, all the complexity that is at fault for those mistakes is actually the result of a long, like, evolutionary journey that gets us to a place where our brains are pretty good remembering the important stuff, or at least the gist of it. Gabriel Spitzer, thank you so much for coming on the show. Emily, it was my pleasure.

Gabriel Spitzer edits and reports for NPR's Science Desk and is the former senior editor of Shorewave. You can hear his story about another pair of sisters with mismatch memories and the rest of NPR's incredible series on the science of siblings at the the link in our episode notes. Scroll, scroll, scroll, and click on that. This episode was produced by Rachel Carlson and Burley McCoy. It was edited by our showrunner, Rebecca Ramirez, and fact-checked by Gabriel Spitzer. Robert Rodriguez was the audio engineer. I'm Emily Kwong. Thank you for listening to Shortwave from NPR.