Forget About It!

0:00This is Hidden Brain. I'm Shankar Vedanta. In Chinese mythology, Meng Po is sometimes known as the goddess of oblivion. She polices the land of the dead and has a special responsibility. She makes sure that souls on their way to being reincarnated do not remember their past lives. To ensure this, she prepares a soup with five ingredients. Her five-flavored soup of oblivion produces immediate and permanent amnesia. the soul can now proceed to be reincarnated with no memory of previous lives. There are rare occasions when spirits fail to drink the five-flavored soup, and when these souls are reincarnated, they become humans who can remember their past lives.

0:52Nearly every culture in the world has stories and legends about memory and forgetfulness. Our ability to remember long-ago events is a signature accomplishment of the brain. Our inability to remember important things is an endless source of frustration. Today on the show, and in a companion story on Hidden Brain Plus, we examine the science of forgetting. We look at why our minds hold on to some memories for a lifetime, but discard others within seconds. And we answer a question many people ask themselves. Is my forgetfulness a sign that something is wrong with me? Forgetting to remember and remembering to forget, this week on Hidden Brain.

1:50In Charles Dickens' novel, Great Expectations, we are introduced to the character Miss Havisham. Many years earlier, she was jilted at the altar on her wedding day. She becomes obsessed with this moment and cannot move on from it. She surrounds herself with reminders of that day, wearing her wedding dress and keeping the clock stopped at the exact moment of her wedding. In so doing, she becomes consumed with sadness. She becomes a prisoner of her own memories. The memories we carry say a lot about who we are and how we see the world. At University College Dublin, psychologist Kira Green studies how memories are formed and the roles that both remembering and forgetting play in our lives.

2:31Kira Green, welcome to Hidden Brain. Hi Shankar, thanks for having me. Kira, I want to talk about something that happened to you some time ago. You live in Dublin and it's common for people to get around by bike. You were riding your bike on the way to a piano lesson. Can you describe the day for me? Sure. It was about three years ago and it was a rainy November night and it was dark and it was starting to rain and it was just a kind of cold, miserable night. And I was leaving work to go to my piano lesson and I was in a rush. So, you know, I rushed down the stairs and I got down to my bike and I realised I'd forgotten my helmet.

3:08So I rushed back upstairs and all the way back up through this very large building and got my helmet, went back down. So then I was running late for my lessons. Ciara started zipping through the night to her class. The roads were slick. I was cycling through Donnybrook, which is a kind of a busy road. And on that road, there's a lot of buses, there's a lot of cars, there's a lot of cyclists. And what there isn't on that part of the road is a bicycle lane. The bicycle lane had stopped earlier. So in fact, as I was cycling along, I was weaving around traffic and in around buses. So I was cycling on wet roads.

3:47It's going too fast. And you can probably see where this is going because I skidded on the bike and I skidded right in front of a bus, which fortunately didn't hit me. But it was one of those e-bikes, an electric bike. So it has, you know, the electric power in it, which means it's very heavy and the down tube is really heavy. So as I fell, my leg got caught in the down tube and snapped my leg in half. It's like if you could imagine a little small bunch of twigs and then you snap those twigs. They don't snap cleanly. They snap with shards. And I had this very strange experience where I, you know, I've heard of this happening before but I'd never experienced it where I didn't feel the pain straight away.

4:28I was lying on the ground and, you know, you get that moment of shock and I was lying on the ground and I tried to stand up and I couldn't stand up and I didn't know why I couldn't stand up. And then I looked down and my shoe had come off somewhere. I don't know where it had gone but my shoe had come off. But my leg was dangling, like a stuffed sock. The bus driver came rushing out and he was like, are you OK? And I was like, well, no, I think I broke my leg. But it still didn't hurt. And then it was only a little while later that the pain started to come in. The bus driver called 999, so we called the emergency services.

5:10but it took nearly an hour for the ambulance to get there because it was a very busy, wet evening so they snarled up in traffic. As Ciara waited in the rain for the ambulance to fight its way through traffic she started to experience the kind of pain she had never dreamed possible. This incredibly sharp, overwhelming, almost electric pain. And I suppose it's because it's nerve pain essentially It's the shards of the bones sawing against the nerve. I've never had the experience before where I would actually scream with pain, but not intend to. It was completely involuntary. I'd feel like screams were being drawn out of me against my will.

5:52Just incredibly agonising, like electrifyingly sharp, overwhelming, blinding pain. You know in a hospital where they ask you, you know, like, how's the pain on a scale of 1 to 10? My previous 10 was now a 6 on the broken leg scale of 1 to 10.

6:10Around midnight, doctors decided to try and set the leg. They told Ciara they would give her anaesthesia. I'm allergic to one of the most common anaesthetic, so they said, we'll try ketamine. I'd never had ketamine before, and I'm sure if you're taking this for recreational purposes that maybe it's a good time. if you're starting out in a happy state and you're comfortable and relaxed with friends. But if you're starting out in a state of fear and pain, it was terrifying. It was a really, really terrifying experience. It felt like it lasted about a thousand years. I had this incredibly vivid hallucinations.

6:50And I came to believe at one point that I had ceased to exist, that I no longer existed. and I could feel not pain but pressure, which obviously in retrospect was pressure on my leg as I tried to set it, but it felt to me like I was being compressed through, I felt like I was a train being compressed through a train tunnel and it was this really, really surreal and very frightening experience and I've had a lot of flashbacks to that experience since. And then after all that, it didn't work. They tried to set my leg and they put it in plaster, but it didn't work. So then they said, actually, after all that, we need to do surgery anyway.

7:30I'm assuming there must have been a very lengthy period of rehab after this much work on your leg, Ciara Yeah, so I mean I couldn't walk at all for several months I was on crutches then afterwards for six months and there was very extensive physiotherapy and rehab and so on It's three years later now and I do still have pain in my leg You know, it's much, much better and I don't limp anymore mostly, I can walk fine but I used to dance and I used to do things that I can't do anymore. So, you know, it has had a lot of knock-on consequences in my life. More than I think, I think previously I would have used the expression, you know, of somebody breaking a leg.

8:07Oh, you might break a leg. And you think it's, you know, unpleasant but not a huge deal. But it was quite life-altering in a lot of ways.

8:20I'm wondering how the memories of this event have stayed with you have you been able to get back on a bike have you been able to go back to the place where the accident took place what's happened? Yeah so definitely the memories have stayed with me I'll find myself kind of repeatedly thinking about parts of it in terms of getting back on a bike Like, well, of course, I couldn't for a long time because I was physically, I was totally unable to. I was in a wheelchair for a while and then I had, you know, crutches for a long time. And, you know, but then maybe six, seven months after the accident, I did get back on the bike.

8:57I just said, right, I'll do a short cycle from my house down to my parents' house, which is not, you know, maybe a few miles. It's not very far. And I did it and I was proud that I did it. But my heart was going, just going like the clappers the whole time. And I found that I couldn't release my, I had this death grip on the handlebars and I couldn't release my hands from the handlebars enough to turn right. So, of course, we drive in Ireland on the left hand side of the road. So turning left is easy enough. You just stay on the side you are. Turning right involves crossing over the road. You have to indicate.

9:31So I did it to prove to myself that I could do it. But it was such an anxiety provoking experience that I couldn't. And I feel there is a thing with a lot of activities like cycling where you need to have a sort of illusion of invulnerability in order to do it. And that illusion was completely shattered. But I knew how vulnerable I was. And there was no getting around that. There was no pretending that this was a safe thing to do. I no longer believed that it was in any way a safe thing to do. So I still have the bike and I still want to get back on it. But I've never gotten back to being able to cycle to work, for example.

10:05And when you consider sort of going on the bike, when you consider the inconvenience of parking and you say maybe I should bike today, what happens in your mind? What does your mind say? I don't think I've even really gotten to that stage. I think if I was even to think about, you know, would I do it tomorrow? Because I'd have to plan. I'd have to think, well, you know, I'll pack the bike bag and I'll pump up the tires, you know, on the bike. And just straight away, I'm just like, no. There's always a thing. It's particularly, I live in Ireland. It rains a lot. This is no surprise. If I look out the window and it looks like it might be wet, it might be rainy, the road might be slick, absolutely no way.

10:40The thought of getting on the bike is really very frightening. I start to feel very anxious about it. So even if I'm driving and I see people, you know, cyclists weaving around, I get so anxious on their behalf. What if they slipped? What if they fell? What if they got knocked down? What if they had an accident? But it's absorbing a good amount of my attention. You mentioned a second ago that what happened at the hospital was also in some ways very difficult, that in some ways you continue to have these memories. Are you still bothered by those memories of what happened when you received ketamine and when you were in the hospital?

11:16Yes, to a certain extent. But then I had a strange experience maybe a year and a half ago. So maybe again about a year and a half after the accident. I had laser eye surgery. It only takes about 10 minutes. And it's not painful. They put, you know, anesthetic eye drops into your eyes. But obviously your eyes are open for the surgery and there's, you know, a laser coming in and doing things and there's a lot of pressure on your eye. And when they're doing that, you see strange things like it looks like kind of like a tunnel. You know, you have that kind of vibe of things looking like things are coming away, shooting away from you or coming towards you like they're down a tunnel.

11:49And I had this almost flashback to that ketamine experience where I told you it felt like I was being compressed and squeezed down a tunnel. And it was just the visual elements of that gave me this kind of reaction. And I knew that's what was happening at the time. And I didn't have a panic attack or anything. But I was aware that I was like, God, this is like that. And it made it very, very unpleasant. And it felt like a long 10 minutes.

12:14All of us want to have a sharp memory. But Keira's painful memories of her bike accident raise an important question. Is a sharp memory always a good thing? You're listening to Hidden Brain. I'm Shankar Vedanta.

12:49This is Hidden Brain. I'm Shankar Vedanta. Most of us wish we could remember things better. We think of forgetting as a flaw. But being able to forget some things can be a blessing. At University College Dublin, psychologist Keira Green cites the example of a woman with an unusual ability. So Jill Price is a woman who's very well known because she has an extremely rare condition that's called highly superior autobiographical memory, which is usually abbreviated as HSAM. And what it is, is a really extraordinary memory for the events of your own life. So somebody with HSAM, like somebody like Jill, for example, will be able to tell you in enormous detail about all the incidents of their lives.

13:33Like somebody who you might be able to say, tell me what the weather was like on the 30th of September 1998. And most of us would go, how on earth would I possibly know that? But somebody with HSAM, someone like Jill, would say, oh yeah, I remember it was really sunny, but the clouds came over at about three o 'clock. We thought for a while it was going to rain, but then it didn't. And I was hanging out with my friends and my friend picked me up. And then we went off down to the shopping centre and we hung out outside Claire's Accessories. And my friend was thinking about getting her ears pierced and, you know, would be able to give you this extremely detailed blow-by-blow account of their own personal experiences.

14:11So Jill Price wrote a memoir about her condition. And in the memoir, she tells a story about something that happened to her when she was a child. Tell me the story, Akira? So she tells the story that her dad used to work as the agent for Jim Henson, who, of course, was the creator of the Muppets and, you know, the brain behind Sesame Street. And, you know, he would tell all these kind of stories about, you know, to the family and everything, all about Sesame Street and about Jim Henson and how incredible it was. And at the time, Jill was very young. She was in nursery school. But her dad arranged for her whole class to go on a field trip to Jim Henson's studio, where all of the puppets were created.

14:53And this, you know, they've talked it up for ages. And this is something, of course, that they were all really, really looking forward to it. But when the day came around for the field trip, Jill was sick. She had tonsillitis. So she wasn't able to go. And of course, being very, very young, she didn't understand that, you know, her father had already committed to this and had already committed to take the whole class with her. So they had to go ahead. Without his own daughter, they had to go ahead and run the trip. and she was devastated. Couldn't understand why he was doing this, taking all of her friends, leaving her behind.

15:24And even though she had tonsillitis, so she had a really sore throat, she stood, you know, like screaming at the top of her lungs, screaming at her parents, so they were not letting them go. And she says, you know, that it was a small thing in retrospect, but that when every time she thinks about it, she still feels this overwhelming sense of disappointment every time she sees the Muppets. So every time you see a Muppets Christmas carol, you're brought back to this moment. I've not just a rose-tinted view of, oh, ha-ha, this is a funny thing that happened to me as a child, but really, like, almost being right back there again and feeling it as though she's right there in the moment.

16:05Now, because she has this extraordinary memory, this extraordinary autobiographical recall for things, she remembers very vivid details about what happened that day. She remembers hearing her mother walking away from her and hearing the sound of her mother's heels as they walk away from her. Really, really detailed. Now, what's striking, of course, is that when things happened to us many years ago, in time, our memories start to fade. We start to forget details of it. But that seems like that's not the case for Jill. No. So it's actually it is very unusual. Whereas, say, my memory of a childhood event might be very, very fuzzy, very foggy.

16:42I might remember kind of a core detail of that event, but I might not remember how I got there or what happened afterwards or what I was wearing. All of those really, really clear details. Those are still very vivid in Jill's memory. I remember a time when I was running around. I must have been 12 or 13. It was dark. I think I was in a parking lot somewhere. I tripped and fell. I landed very hard on my finger. I broke my finger. It was very painful at the time. But now when I look back on it, you know, I look back on it and say, you know, that's what being a kid was. You know, you ran around, you did silly things and you had injuries.

17:18I no longer remember the pain. I don't remember the details. To be honest, I'm not even sure which finger was actually hurt anymore. But with Jill, because she has this detailed memory, the memory is also painful in a way for her that it's not for me. Yeah, exactly. So a lot of the time, really, what's happening here is that she's constantly reliving these same experiences and kind of perseverating on them and thinking about them. And it does mean then that you're not able to let some of these things go. So we often tend to think of this kind of really extraordinary memory as being an extra gift, that it's this extra wonderful thing that you have, this skill that you have.

17:57And in some ways, of course, it is. And a lot of people who have this condition or who have this ability think of it as being wonderful. But there are significant downsides. And one other way of thinking about this is that it's not so much a great ability to remember as it is an inability to forget. So Jill Price doesn't just remember this one childhood event. She remembers other things in her life. Tell me the story about her husband, Jim, and what happened to him, Keira. So, yeah, so in the book, Jill talks a lot, firstly talks a lot about how she met her husband, Jim. And, you know, they had been, had a kind of a long distance relationship at first.

18:33And then when they met, they had this really, really strong connection and, you know, fell very deeply in love and got married and, you know, lived together. Had this, you know, from her recollection, had this wonderful marriage. But there was this extremely tragic end to it, which is that only after only two years of marriage, when Jim was only 42, he died. He had very severe diabetes and he suffered a stroke as a result of that and died as a result after several days in the hospital. Now, one of the things that's striking is that because Jill had such good memory, she could remember many of the good times in great detail, perhaps in much better detail than many of us could have remembered it.

19:12She remembered when she first met Jim, you know, that first night together, what their wedding day was like. She remembered the good times in extraordinary detail, but that also meant that she remembered the tragic end in excruciating detail. Yes, exactly. And I mean, of course, many people listening might be saying, well, I remember my wedding day as well. But I think the thing is that it's not just these these big key events that she remembers. It's also just everyday things. And she will remember not just our first date was great, but every detail of it in extraordinary clarity. but yes towards the end then as well she also cannot allow those those terrible memories of Jim's illness and death to fade and so she describes in really great detail how when she you know her father came home and told her that Jim had collapsed at work and then they're driving to the hospital and she goes through in this just exhaustive detail every phone call she made to the nurse and then the nurse is telling her this and then you know all these details of the drive to the hospital and then you know what the doctors were you know this horrible situation where he was in critical care for days and then eventually the doctors had to tell her they had to turn off the life support machines.

20:20The fact of this terrible thing happening is something that everyone would remember and like nobody's going to have forgotten that their husband died so tragically but it's every little detail of it and she says that even like every time now years and years later she can't drive down that road where they drove to the hospital because every vivid little detail of that drive to the hospital is there as comes comes back and they don't fade with time. You know we have that that cliche that time is a great healer and we do tend to see that that over time our negative memories tend to fade and we tend to hold on more to the positive memories.

20:56There are exceptions but Jill's memory really doesn't seem to discriminate. She holds on to all of those details whether or not they're still relevant whether or not they're useful to her she's still holding on to all of them.

21:14Kira, say more about this idea. I think when many of us think about forgetting, we think about forgetting as a flaw. You know, I find myself forgetting things all the time and whenever I forget things, I'm so upset with myself. And I say, you know, I used to have a fantastic memory and now my memory is failing me. It's not good. I worry if I have a disorder of some kind. Talk about this idea that in some ways we get it profoundly wrong when we think about forgetting as a flaw. Yeah, so I think the first thing to note is that forgetting is actually a fundamental component of memory. We tend to think of forgetting almost as the flip side of memory, that memory is the positive of what we're supposed to do, and then forgetting is the accidental thing that happens.

21:55But that's really not the case. Forgetting is a fundamental element of what happens in our memory processes. I think a lot of the problem here comes in that when we tend to make the mistake of thinking that our memories act like a computer system, that we should be able to just file away information and then it will stay in that same place. And then later on, we should be able to retrieve that information and we pull it back exactly the same way it was before. And if we had a computer where we went to go and retrieve a file and the file wasn't there, it had been accidentally deleted, we'd be disgusted.

22:23That's not what a computer is supposed to do, right? A computer is supposed to retain this perfect record of information as we recorded it. But that's not what our memories do. That's not how our memories work. Rather than thinking of memory as being this kind of passive process where we just file information away and then it just stays there, memory is actually this really active process where we're kind of actively engaging in our memories. We engage in actively constructing and reconstructing our memories and we change the way our memories are stored in our brains. And part of that process is that forgetting is a kind of a natural sort of digestion process in memory, that we have lots and lots of different events in our lives.

23:01And one of the really key things that our memories do, and that forgetting helps us do essentially, is to identify the gist of those memories. So for example, right, like imagine every day probably you eat breakfast, okay, and probably most days you eat more or less the same thing for breakfast. Maybe you eat something different on the weekends than you do the weekdays. Okay, but probably you eat the same thing more or less every morning. You could, if you think of that computer metaphor, you could imagine that for every single day of your life, you should have a perfect, veridical recollection of exactly what you ate for breakfast, how you poured out the cornflakes, how you poured out the milk, how you sat down at the table, picked up your spoon, how many bites you ate, how many times you chewed each bite.

23:44But honestly, what a waste of time to remember all of these things in such detail. Really, all you really need to know is to sort of condense all of that information into usually I eat cornflakes for breakfast. Okay. And then sometimes when something a little bit different happens, then we need to be able to remember that. Like, well, we ran out of milk this morning, so I had toast instead. I must remember to go to the shop and buy milk. But most of the time, remembering all of these very repetitive events in our lives in this perfect individual detail, it's actually a really inefficient way of storing information.

24:19Instead, we kind of condense that information down and we pull out the gist of those kind of repeated continuous events. So if you can't do that, if you're not able to kind of essentially leave some of those details behind you, then what you're going to have more trouble doing is identifying the gist, identifying the commonalities among all of those different events.