The Best Years of Your Life

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Shankar Vedantam: This is Hidden Brain. I'm Shankar Vedantam. In one of the movie versions of the Oscar Wilde novel, The Picture of Dorian Gray, the actor Hurd Hatfield stares longingly at a painting of himself. The picture shows a young man bursting with health and vitality. As Dorian Gray reflects on how he is going to change with age while his picture will stay the same, a strange wish passes through his head.

Dorian Gray: If only the picture could change, and I could be always what I am now. For that, I would give everything. There's nothing in the whole world I would not give. I would give myself for that.

Shankar Vedantam: In the story, Dorian Gray makes a pact with the devil. The painting starts to age in his place. The physical degradation of the picture isn't only about the passing years. The picture takes on the corruption of the character's many misdeeds. Meanwhile, Dorian Gray himself stays eternally youthful.

Oscar Wilde wrote the story in the late 19th century. The movie came out in the middle of the 20th century. The 21st century is not that different in its preoccupations from its predecessors. Movies, TV shows, and the fashion industry still worship at the altar of youth. People around the world spend billions of dollars on potions and injections, and surgical interventions to keep the signs of age at bay. Clickbait ads on many websites show you what the youthful stars of yesteryears look like today. The message couldn't be clearer. Aging is a terrible thing. Growing old is a horror show.

This week on Hidden Brain, astonishing new research about aging that could change the way everyone thinks about life.

If you're short, you don't know what it feels like to be tall. If you're white, you won't know what it's like to be black. Lots of aspects of identity are like this. They are fixed, but there is one form of identity that is certain to change with time. Young people today will become old people tomorrow. But while growing old is inevitable, it comes with so much psychological and cultural baggage that lots of us avoid thinking about it.

In popular culture, getting old means getting kicked out. Lots of elderly people discover that aging makes them invisible to others. At Stanford University, psychologist Laura Carstensen has focused her attention on the topic of aging. She has discovered some astonishing things.

Laura Carstensen, welcome to Hidden Brain.

Laura Carstensen: Thank you. Pleasure to be with you.

Shankar Vedantam: Laura, I want to take you back to 1974 when you were 21 years old. Like many young people on the cusp of adulthood, you didn't give much thought to aging. What would you say your priorities were at this time of your life?

Laura Carstensen: My priorities were dating, exploring, and thinking about future jobs and possibilities, and where I would live, and what I was going to do the next day, the next week, the next year. Thought a lot about my future. I didn't think at all about aging.

Shankar Vedantam: Your life changed very dramatically one night that year. I understand that you and some friends were going to a concert. Tell me what happened, Laura.

Laura Carstensen: Yeah, I worked as a waitress in a restaurant and a bunch of us after closing decided we would go to a concert. It was about an hour outside of town, and we divided up into cars, drove out, and we went to this concert. At the end of the evening, we said, "Well, let's go back and play some pool." So, we divided up again into different cars and started to head back to town.

I happened to get in the car with a man I hardly knew who was very drunk. I caught onto that pretty quickly and asked him to stop. I remember putting my hand out on the dashboard as he was going ever faster. And that was the last thing I remembered before waking up in a ditch on the side of the road.

He drove off the road and rolled down an embankment. The car turned two or three times over, and I broke about 20 plus bones, but my left leg was injured most badly. My femur cracked in half, and I had many other fractures through the knee and the ankle, and I had cracked ribs. I had a concussion, lots of facial lacerations, lots and lots of injuries.

Shankar Vedantam: I'm assuming there were a bunch of surgeries that must have followed this and very intense hospitalization.

Laura Carstensen: Yes. For the first couple of weeks, they couldn't do surgery. Because I had been injured so badly, they couldn't give me anesthesia. So, those were the toughest two weeks. Then they began a surgery, but mostly, they just kept my leg hanging in the air. It's that cartoonish image you have of someone laying in a hospital bed and the leg is being held upwards, and that would keep it somewhat straight.

Shankar Vedantam: Was there a period in this window, Laura, where people were afraid that you might not make it? I mean, it sounds like this was a very, very serious crash and the injuries were really serious.

Laura Carstensen: Yes. Certainly, there was the expectation that I may not make it. I remember at a point during that time, I wished I wouldn't make it. In hindsight, I remember thinking there are things worse than dying, but I kept becoming unconscious but then coming out of it again in those early days, and eventually, started to heal.

Shankar Vedantam: I'm wondering if your priorities changed around this time. You talked about how your priorities at age 21 were the priorities of anyone who was age 21. You're thinking about what's happening next week, next weekend. You're maybe thinking about your dating life. You're thinking about your career. How did that worldview change as a result of the crash?

Laura Carstensen: I, like many people who have these near death experiences, completely changed how I thought about life. Suddenly, life was something I didn't take for granted anymore, and life wasn't to be lived for fun and entertainment and exploration. I, for the first time, really saw how valuable time was.

Shankar Vedantam: Laura's social world changed too. A large circle of acquaintances was replaced by a bright spotlight on a small group of family and close friends.

Laura Carstensen: And for that, I felt incredible gratitude to be surrounded by people who really cared about me. My parents came to visit. My siblings came to visit. My dad came every day. I don't know what I would've done without that connection to the outside world and without the knowledge that I was embedded in a group of people who cared.

Shankar Vedantam: Tell me about your recovery. I understand that you were in the hospital for several months as you were recovering from these injuries.

Laura Carstensen: The way I remember this, it was about a month and a half before I thought about much of anything other than my injuries and how badly I had been hurt. But then I started to wake up, if you will, and I started to get bored. When you lay flat on your back with your leg up in the air, strung up in the air, there's just so much you can do day to day, and I got really bored.

Shankar Vedantam: Laura's father, who was a professor, offered her a way out of her boredom.

Laura Carstensen: He had always wanted me to go to college. I had not gone to college up to that point. I was 21 in this accident, and he suggested when I complained about being bored that maybe I should take a course. I was resistant to it. And he said, "Really, just name a course." And he would go tape the lectures and bring them to me. So, I took introductory psychology as a hospital patient laying flat on my back with my leg tied in the air.

Shankar Vedantam: Wait, so your dad actually sat in the psychology classes and recorded them and brought you back the cassettes to listen to?

Laura Carstensen: My dad was a saint, yes. My dad was a biophysicist, by the way. And when he first asked me what I wanted to take, I was saying, "Oh, not physics." And he said, "No, anything, anything." So, yes, he went to every lecture of introductory psychology with a tape recorder and tape recorded the lectures and brought them to me in the hospital.

Shankar Vedantam: Wow.

Laura Carstensen: Yeah.

Shankar Vedantam: So, while you were in the hospital, the nurses assigned you a task, which was also in some ways perhaps a psychology workshop, of talking with some of the elderly patients who were in the same ward as you. Why did they ask you to do that, Laura?

Laura Carstensen: Well, I had gotten to know the nurses. Again, you're with the same people day after day. And so, we had begun to talk a little bit, and I complained to them about being bored. And they said, "We've got an assignment for you. There are a lot of older women who come into the orthopedic ward and we're going to put them in this room with you." I was on a four-bed ward, "And your job is to talk to them and keep them alert, so they don't get confused and so on. We're giving you that job." So, two things happened. One, I'm taking introductory psychology. And the second one is I've now been assigned to talk to older women.

Shankar Vedantam: Now, I can't tell whether this was a psychological intervention to help you or a psychological intervention to help the people you were talking with, but perhaps it was both at the same time.

Laura Carstensen: Well, really, this was about helping me. They were trying to give me a gift of a job.

Shankar Vedantam: Is there anything you gleaned from the time you spent with these elderly patients in the ward?

Laura Carstensen: So many things. I learned so much from this experience about aging. For one, their lives were so different from one another. And their personalities and their outlooks on life were so different from one another. That to the extent that I had stereotypes about what older people were like, they went quite far in challenging those stereotypes.

One woman that I shared a room with was a matriarch of her family, and these young kids would come in and sit on the bed and talk to her. There were other women who were really sad, really in a tough situation. I remember one woman in the hospital room who had to sell her home in order to pay the hospital bill before they would discharge her. And so, she had to be transferred to a nursing home instead of back to her own home, and it was all for financial reasons.

There was another woman who just laid in her bed and stared at the ceiling all day. The physicians would come in. They'd surround my bed. They'd be trying to do all sorts of things to help rehabilitate me, get me better thinking about my future, and then they would just wave to her on the way out the door. Say, "Hey, Sadie," and just keep going. They didn't pay much attention to her at all.

There was another insight I had from spending so much time with these older women who were also spending all their days in bed being cared for by other people, and that insight was just how much we had in common. I was 21 and these women were in their 70s and 80s and probably 90s, but we were all dependent on other people for everything, from being fed to staying clean, to having any social interaction. I mean everything, we were dependent on.

Suddenly, I shared these characteristics that I would have thought of as characteristics of old people or sick people, but now, it was me too. And so, that also changed, and it made me think about the world and how the world comes to shape who we are. And the one insight I had about aging, or at least was at the beginnings of my thinking about aging, was that aging is a biological process, but it's driven, shaped by the social world. And that was the insight that led me to be interested in the science of aging.

Shankar Vedantam: Laura spent four months in the hospital. After she was discharged, she was in a wheelchair for a while and then walked with a cane for several years after that. While she gradually recovered from her injuries, the hospital experience stayed with her. She finished college, went to graduate school, and decided to become a researcher who studies the science of aging. She was soon to discover a phenomenon that affects not just the elderly, but everyone at every stage of life.

That's when we come back. You're listening to Hidden Brain. I'm Shankar Vedantam.

This is Hidden Brain. I'm Shankar Vedantam. Laura Carstensen is a psychologist at Stanford University. She's the founding director of the Stanford Center on Longevity. When she was a young woman, she sustained some serious injuries in a car crash. As she recovered in the hospital, she found herself surrounded by elderly patients with many infirmities. The experience helped her decide to specialize in the science of aging.

Laura, when you started your career as a psychologist in the early 1980s, there was a scientific consensus about what it meant to grow old. Was it fair to say that that consensus was a grim one?

Laura Carstensen: Oh, it was grim indeed. Aging was considered to be a serious threat to virtually everyone's mental health. There was a clinical psychology textbook that I had when I was in graduate school. This was a textbook on psychopathology. They had a chapter on anxiety, a chapter on depression, a chapter on drug abuse, and then they end a chapter on old age. So, old age itself was considered pathological.

Shankar Vedantam: And I'm assuming that when scientists were talking about the pathologies of old age, they were referring to things like declines in cognitive function, impairments in memory, depression, anxiety, a whole range of problems.

Laura Carstensen: The whole range. And at the time, people also believed that Alzheimer's disease was the inevitable consequence of aging, so that cognitive impairment would begin and would eventually progress to dementia, so that that was the fate of people who lived very long lives.

Shankar Vedantam: Soon after you started working as an academic, the National Institute of Mental Health funded a study to assess the prevalence of psychiatric disorders. What did it find and what was its impact on you, Laura?

Laura Carstensen: Yes. This was an epidemiological catchment area study of mental health conducted in the early 1980s, and it was not a study designed about old age at all. It was a study that was designed so that the researchers could get a better estimate of different forms of psychopathology in the community. And so, what they did was to have trained clinicians go out into the communities and interview a representative sample of people in a number of different geographical areas around the country.

It was the best epidemiological study of mental health that had been done in this country, probably anywhere at the time. The results of it were to give them pretty good estimates of the prevalence of anxiety, depression, phobias, et cetera, et cetera. And one of the findings that was embedded in this set of findings about prevalence was that the prevalence of every form of psychopathology, with the exception of the dementias, was observed at lower rates in older people than middle-aged or younger people.

This really turned on its head the idea that psychopathology, mental health problems, depression, anxiety, were part and parcel of growing old.

Shankar Vedantam: The National Institute of Mental Health study was studying emotions associated with psychiatric disorders. Laura wanted to broaden the picture, what were the everyday emotions experienced by people who were young, middle-aged and elderly? To find out, she ran a study that measured the daily emotions of people ranging in age from 18 to 94.

Laura Carstensen: We studied a whole range of positive emotions and negative emotions. We wanted to understand what emotional experience in day-to-day life was like. We knew from this large study of mental health problems that they had lower rates of that, but we didn't know a lot about what day-to-day emotional life was like in old age.

And so, at the time, we designed a study using what was then the gold standard, probably still is, of studying emotional experience in day-to-day life. And we gave people pagers, electronic pagers, and they carried them for a week. And at random times during each of seven days, we paged them and asked them to tell us the extent to which they were feeling each of 19 different emotions. Some were positive emotions like joy, happiness, calm. Some were negative emotions like anger, sadness, fear. And so, we had this detailed record now for individuals about their emotional lives.

Shankar Vedantam: So, the NIMH study was finding that older people, in fact, were not suffering from higher levels of psychopathology. You were studying, if you will, more ordinary emotions, everyday emotions. What did you find in terms of the everyday emotions of the young, the middle-aged, and the elderly?

Laura Carstensen: We found that increasingly older people had fewer negative emotions, less anger reported, less fear, less disgust, and just as much happiness, joy, calm. And so, this was consistent with these findings about psychopathology as well. Now, we had a normal healthy population from the community and we were observing something similar.

Shankar Vedantam: Now, it must have felt a bit like a head scratcher. Given all that we had heard about how aging is a horror show, did you ever worry that you had something wrong in the data?

Laura Carstensen: It wasn't just us who worried about it. It was the whole field that was in disbelief. The general public didn't buy it. More importantly, the scientific community was very eager to scrutinize these findings and figure out what was wrong. And in science, nothing better can happen than that, having a finding that lots of other laboratories, lots of other investigators say, "I don't quite believe it. I'm going to look at it this way. Maybe X explains it. Maybe Y explains it."

So, there was one alternative that people were reporting that they were happy because they didn't have the cognitive ability to really ruminate and generate lots of negative emotions. That is, if you can't remember how upset you were yesterday and how people treated you, then you're not going to feel bad about it. So, one was that cognitive impairment was actually leading to more happiness.

I refer to this within my own research group as the village idiot hypothesis. It's just like if you really can't appreciate just how bad your circumstances are, why you're happy. Lots of studies have looked at the relationship between everything from executive functioning and education to intelligence, and this positive outlook on life, and it's the reverse. People with the highest levels of executive function and cognitive abilities and education, those are the ones showing this effect the strongest. So, we ruled that one out.

Then there was a hypothesis generated by many in the field of psychiatry that was called masked depression. That is really older people were terribly depressed, but they were covering that up because it was a way of keeping it from others, but more importantly, fooling themselves. So, we did studies and others did studies where we would have people experience different kinds of emotions while they were in brain scanners and be able to look at activation of different regions of the brain. Again, you couldn't explain it through a lack of activation.

A lot of research was done to try to explain or reconcile that this was really just cognitive impairment or brain impairment. It was really about something else. But with every study, it became clearer that this was a highly reliable finding. Older people were happier in their day-to-day lives, on balance, than younger people were.

Shankar Vedantam: So, eventually, the weight of all this evidence convinced even the skeptics. And the finding that older people were in fact happier than younger people was dubbed the paradox of aging. What was the paradox, Laura?

Laura Carstensen: Well, the paradox really was that aging entails a lot of bad things. Cognitively, people often do change. Feel that memory isn't as good. Attention is tougher to keep in focus, not to mention the physical changes with age. Most of us experience more aches and pains. So, all these things are changing. Then in the societal context, people aren't taking us as seriously as they used to. There's an invisibility people talk about when they get old. That people walk almost right through them, and they're just not noticed. And so, if all of that's happening with aging and it is, how could it be that older people are emotionally doing well?

Shankar Vedantam: And it does seem like a mystery because, of course, social status, physical health, friendship networks can become more limited. Social engagement can decline. And you will think that, if all those things happened, if you had less social status, less physical health, a smaller network, lower levels of social engagement, you would predict that the people would then have worse psychological health. And yet, psychological wellbeing seem to be improving.

Laura Carstensen: Yeah, it challenged all of our basic assumptions about what gives us happiness. It's having a lot of friends. It's having a bright future. And here, the older we get, the closer we are to death. How could it possibly be that people get happier?

Shankar Vedantam: So, as you were trying to tease apart this mystery, in some ways, there's the fact that the data coming in was so at odds with the intuitions and cultural beliefs that many people had about aging. You stumbled on an answer to that mystery one day as you were interviewing a pair of elderly siblings, Laura?

Laura Carstensen: Yes. One day, I interviewed two sisters who lived together in an apartment in San Francisco. It was an apartment that housed a lot of older people. They were talking to me about how sad they were that they had lost many good friends and relatives as they'd gotten older. And I said to them, "What about new friends? There are a lot of people who live here in this building, and do you reach out to them? Do you want to make new friends?"

I remember them giving me this blank stare, like you just don't get it. And they said, "Laura, we don't have time for those people." And I looked at them and first thought, "You don't have time? Come on, you've got a lot of time on your hands, don't you?" Then I went away, and they were kind enough to send me off and be sweet to me. But I went home and I remember sitting at my dining room table, staring out at the San Francisco skyline, and it was this moment where I feel like I had an epiphany where I said, "It's about time."

And I realized that it wasn't about time in the day; it was about time left in life. And if our time horizons are changing, if they're getting shorter as we grow older, then our goals may systematically change. And everything in my life, in my research, changed after that evening.

Shankar Vedantam: Laura's epiphany was quickly followed by a second moment of insight. She realized her own life contained a case study of the very phenomenon the elderly siblings had demonstrated to her. She thought back to the time she had come close to dying at the age of 21. She remembered how her priorities, her social world, had changed dramatically.

Laura Carstensen: I didn't know that I was going to make it through those months of recuperating. And the idea of exploring this very large world full of possibilities was of no interest to me either during that time, but I did care about things. It wasn't a flattening of emotions. It was a very sharp focus of what matters and what doesn't. And it's very much tied to time, time left.

Shankar Vedantam: When we come back, the powerful force that shapes us throughout our lives from youth to old age. You're listening to Hidden Brain. I'm Shankar Vedantam.

This is Hidden Brain. I'm Shankar Vedantam. Laura Carstensen is a psychologist at Stanford University. She's the author of A Long Bright Future: Happiness, Health and Financial Security in an Age of Increased Longevity. While conducting research on the surprising emotional resilience of elderly people, Laura identified a powerful subterranean force that was shaping the outlook of the individual she studied. This force had to do with how people of different ages and people at different life stages perceive the amount of time they have left in their lives.

Laura Carstensen: Humans, to the best of our knowledge, are the only species that appreciates our mortality throughout most of our lives. There are other species like elephants, lions, they probably know when they are dying, but we anticipate how much time we have left throughout the course of our lives, and we do this subconsciously most of the time.

Then every once in a while, events occur that prime mortality. It could be the death of a friend or a terrorist attack, a war. Something happens that reminds us that we're mortal. We're not going to live forever. We don't have all the time in the world. And as we get older, we increasingly experience those kinds of reminders. And so, we come to take account of time and value time differently. Goals change systematically as our time horizons change.

Shankar Vedantam: So, let's delve into that with a little more detail. When we are younger, take, for example, the undergraduates that you're teaching at Stanford, obviously, they are young people. They have their entire lives in front of them. What are their time horizons, and how does it affect how they're thinking, Laura?

Laura Carstensen: It's an interesting question because when we began this, we thought younger people think of about their futures a lot, and they envision their futures as very, very long. It turns out the more we've studied this that a clearer answer, a more accurate answer is that younger people don't think there are any constraints on time. So, they don't think about the future so much in terms of how much left there is. It's that it's just vast. It's abundant. They don't need to think about time. And it's really the shift is as we grow older, where we come to think about time more, how much time we have left. But for young people, they have all the time in the world, essentially.

Shankar Vedantam: So, as we get older, the shifting time horizon has a number of different kinds of effects on our lives and our choices. We talked briefly about this before, but one of the effects is on our social relationships. What is the effect of our shrinking time horizons on our social relationships, Laura?

Laura Carstensen: Social networks get smaller as people get older. And I should note that this was part of the thinking about the paradox of aging. Because social relationships are what bring us our greatest happiness, there was thinking that if networks and older people were smaller than they were in younger people, then older people must not be as happy. That was basically the thinking.

Instead, it appears that what happens is that over time social networks get smaller, but they're very well-honed. And so, the people who are retained in the networks are those that are most important, the people who are most predictable, most valuable in our lives, and those are the relationships that stay. And we let these other more distant acquaintance like relationships fade away. But what it means then is that our social networks as we get older are more emotionally dense. They're people who we really care about. And so, there's a real benefit to that kind of a social network.

Shankar Vedantam: There are so many jokes about how the elderly are incurious. They're stuck in their ways. You can't teach an old dog new tricks. But partly, what I'm hearing you say is that the old dog's old tricks are actually pretty good.

Laura Carstensen: Yeah.

Shankar Vedantam: In fact, the old dog is pretty happy with those tricks.

Laura Carstensen: Exactly. I try to explain this to undergraduates who are having a hard time grasping that. I say, "Imagine that you only had one week left in a city that you'd been exploring. Do you want to try another new restaurant, or do you want to go to your favorite restaurant in that last time out?" And I think that's some of what's happening with age. Exploration is extremely adaptive when time horizons are long. We need to learn. We need to explore. We need to collect because those kinds of things could be useful.

And especially if your time horizon is so vast, anything could happen. So, meeting somebody at a party, even somebody you may not particularly like could end up being an important contact five years from now when you're looking for a job. So, people are collecting and they're very open to that. But as time horizons are shorter, we focus. We focus. We savor. We see better what's important and what's not.

Shankar Vedantam: Another change that accompanies old age and one that also appears to be driven by shortened time horizons is a shift in the kinds of information to which older people attend. Tell us more about this, Laura.

Laura Carstensen: I think this is one of the most interesting findings. Brains do not take in information evenly, but rather goals direct our attention, goals direct our memories, goals direct cognitive resources. And so, with colleagues of mine, Mara Mather and Susan Charles, we began to think one day about whether these changes in goals that we had documented widely in social preferences and social networks would be represented in fundamental aspects of cognitive processing.

And we began to run a study, which since has become widely replicated, but it was a study where we presented positive, negative and neutral stimuli to younger, middle-aged and older adults. And we had them sit in front of a computer screen, and they would go through the images. Then after they've done this viewing, tell us all the images you remember. And what we find is that younger people remember almost the same numbers of positive and negative images.

By middle age, we see a preference and memory for the positive images and in old age, that preference is whopping. That is older people are remembering almost exclusively the positive images, and they're not recalling the negative nor the neutral ones. And so, that was the first time we'd seen this. It was a little surprising to us because we weren't exactly clear why people would selectively attend to positive and not negative too, because negative could be emotionally meaningful. And we thought this was super interesting.

We then ran a study of autobiographical memory. Again, same finding, using neuroimaging where you look at amygdala activation in response to the negative, the neutral, the positive. Again, what we see is more amygdala activation in response to positive viewing than the viewing of negative images in older people. Again, let me loop this back to some of the thinking about how negative aging was years ago.

Prior to the study we did, and this was a study published in the early 2000s, but prior to that, there'd only been one study where they looked at amygdala activation in response to emotional stimuli, but the researchers had only used negative stimuli and older people didn't remember them as well. And so, the conclusion was that the amygdala is broken. There's some neural impairment, but what we showed is the amygdala is activated just fine in response to positive stimuli.

And many people, by the way, think of the amygdala as more of a salience indicator than emotion per se. So, it's what is capturing attention, what's valuable in attention. And since then, as I say, there are now hundreds of studies showing the positivity effect.

Shankar Vedantam: This is actually striking because, of course, there's also a wide literature across the social sciences generally arguing that bad news is perceived more strongly than good news. It's sometimes called the bad news bias. But what you're saying is that really that might actually have an interesting intersection with age.

Laura Carstensen: Exactly. People have long believed that negative stimuli have powerful adaptive, evolutionarily-based value. And so, of course, people, and that was the way these studies were described, people will pay more attention to negative stimuli than positive. However, people, as it turns out, were young college students in virtually all of these studies. So, we were generalizing from what younger people were observed to do to humans writ large.

And actually, what we see now, if we look at the body of research that has emerged since we first identified the positivity effect in cognitive processing, is that there's a gradual age effect in it. And yes, younger people pay more attention to negative stimuli than positive, and then gradually that not only diminishes, but heightened attention to positive emerges.

Shankar Vedantam: Another effect that you and other researchers have examined that looks at the effect of shrinking time horizons is how focused people are on the present versus the past or the future. Talk about this idea, Laura.

Laura Carstensen: There is a stereotype of older people that they live in the past and think largely about the past. There's also a literature and clinical psychology showing that when people think about the past, they're more likely to be depressed. So, that kind of pattern was long believed to capture the obvious depression we would see in older people, but of course, they're not depressed. And here's the finding, they also don't think about the past any more than younger people do, but they don't think about the future as much as younger people do.

So, younger people are rarely in a present focused mode. They're almost always thinking about the future. Older people can actually be in the present, and that tends to be very good for mental health. There are lots of meditations now, Buddhist meditations, that are intended to help people get to that present focus because living in the moment tends to take people's attention to positive aspects of the world.

Shankar Vedantam: So, in many ways, it strikes me that your focus on the effects of time horizons means that this is not really about aging in a chronological sense. It's more about the psychology of how we perceive time. Does this mean that if you experimentally induce younger people to feel like their time horizons are short, that this would then change how they feel and behave?

Laura Carstensen: Isn't that exciting? Yes, it does. Sarah Barber, a psychologist who works also with Mara Mather, ran a study about five years ago where they induced endings, mortality, or approaching the end of your life. And they did this kind of imagery induction with younger people and then presented them with stimuli, positive, negative, and neutral. And younger people also showed this shift and a favoring, a preference for positive information in attention and memory.

What's most exciting actually about this whole line of work is we've been able, in most cases, to just lift age out of the equation and say it's time. It's our beliefs. It's our perceptions. It's our sense of a future that affect the goals that we pursue in everyday life.

Shankar Vedantam: I'm wondering on a college campus whether you can see interesting differences between people who are freshmen and people who are seniors, because in some ways you almost have a natural experiment that's unfolding of people who have a sense of a long time horizon and people who have a sense of a short time horizon, at least on campus.

Laura Carstensen: Yes, you can compare returning sophomores to graduating seniors, and their social preferences for spending time with others. And as you've anticipated, the returning sophomores are interested in meeting new people, and the graduating seniors are not interested in meeting new people. They're interested in spending time with their very good friends.

Shankar Vedantam: Does the effect run in reverse as well? What happens when older people are asked to imagine that they have more time left to live?

Laura Carstensen: We ran an experiment where we ask exactly that question. We thought, "Wow, we can make young people old. Can we make old people young?" And so, in one study before, we asked people to choose from among an array of social partners. We said, "Now, imagine that you just received a phone call from your physician who told you about a new medical advance that virtually ensures you'll live about 20 years longer than you expected in relatively good health. Who do you choose?" And now, older people were no longer expressing preferences for these very well-known friends and loved ones. They were interested in exploration and novelty too.

Shankar Vedantam: I love this because in some ways what you're really identifying is the underlying psychological mechanism here. Regardless of whether people are old or young, it does happen to be the fact that older people, because they have a more limited time horizon, are behaving in a certain way, but you can induce them to behave differently. I'm wondering, once you understand this underlying psychological mechanism, what the implications of this are, are there benefits to pulling back the curtain and looking at how our sense of time left in life might be affecting us?

Laura Carstensen: I believe that there are. Occasionally, I'll give a talk to a largely young audience about these findings. And somebody inevitably comes up to me after the talk and says, "How do I get to be more like an old person? I'd really like to be that." Then what I say is it's not a good idea. That it's adaptive to explore, to learn. And it entails taking risks, including emotional risks, but it's good to do that when you're preparing for a long future. And when you don't have to prepare for a long future, then you can focus on what really matters.

So, in some ways, aging relieves us of the burden of the future. We can be in the moment, and that's adaptive to do that. Now, that said, it will be great if we can find ways to have younger people step out of that future-oriented mode occasionally and really experience the present, see what's positive in the world. This would be really good for them, I believe.

And just the same, there are context occasions where it's really good for older people to think about the future, the long-term future, and not just the present. Think of a climate change, for example. Probably not going to affect somebody too much who's very old today, but good to pay attention to it. And so, yes, we should be able to time travel, so we can step into the future or step into the present.

Shankar Vedantam: I'm wondering whether you do this in your own life, Laura. Having done this research now, do you try and apply this? Do you actually catch yourself at various points in your day saying, "Here's how my time horizons are shaping how I think, and maybe I want to make that choice more mindfully"?

Laura Carstensen: I try to take the findings to heart, and there are a couple of things I do. One is something will happen to me during the day, as these things happen to all of us, that's just really irritating. Or something where I just keep going over it and over it in my head again, like, "Ah, I wish I said this to so-and-so and what." And it really helps to put it in perspective, like if this were the last month of your life, would you care? And the answer is always no. And so, being able to do that, I do think helps.

Then there are moments where I can get lost in staring out the window of my office at home where there are a number of trees, and goldfinches, and bushtits, and blue jays, and they're always out there. And I can just stop and really just love them, just love that experience. Then quickly go back and begin to think about what I have to do next, and what paper is due, and what email I need to return, and I can go back to that. But yeah, it's good to be able to step out of the future demands occasionally.

Shankar Vedantam: You've written that you like to think of two older people in particular. They grew up together in Kew Gardens Hills in Queens, close friends who shared a love of music. While still in their teenage years they started recording songs together and they achieved a lot of success. But over time, disagreements flared, resentments accumulated, and they mostly stopped speaking to each other. Decades later when these two men were past 60, they elected to put their differences aside. And I want to play you a clip of them singing together.

Simon & Garfunkel: Can you imagine us years from today, sharing a park bench quietly? How terribly strange to be 70. Old friends, memory brushes the same years...

Shankar Vedantam: Laura, I'm wondering what the story of Paul Simon and Art Garfunkel can tell us about friendship and forgiveness over a lifetime.

Laura Carstensen: I think there's something powerful to that, and I don't think it's very well understood in the science, but there is evidence that older people are more likely to forgive and that marriages improve. And this is research that comes from John Gottman and Bob Levenson and I that we did together on older marriages. Even unhappily married couples are happier as they get older, and I think some of that is they come to wear the years that they weathered as a badge of honor. They share something together and come to take pride in that and to begin to say, "You may not be perfect, but you're mine." And there's something really moving about that.

Simon & Garfunkel: Long ago, it must be, I have a photograph. Preserve your memories. They're all that's left you.

Shankar Vedantam: Psychologist Laura Carstensen works at Stanford University. Laura, thank you for joining me today on Hidden Brain.

Laura Carstensen: It's a pleasure. Thank you.

Shankar Vedantam: If you have follow-up questions for Laura Carstensen about the science of aging and are willing to have those questions shared with the larger Hidden Brain audience, please record a voice memo on your phone and email it to us at [email protected]. 60 seconds is plenty. Please remember to include your name and a phone number where we can reach you. Again, email the question to us at [email protected] and use the subject line, Aging Questions. [NOTE: This request for questions has now closed.]

Hidden Brain is produced by Hidden Brain Media. Our audio production team includes Bridget McCarthy, Annie Murphy Paul, Kristin Wong, Laura Kwerel, Ryan Katz, Autumn Barnes, and Andrew Chadwick. Tara Boyle is our executive producer. I'm Hidden Brain's executive editor.

Our unsung hero today is a former contributor to Hidden Brain. Dan Pink is the well-known author of many books, including most recently The Power of Regret: How Looking Backward Moves Us Forward. Dan used to be my sparring partner many years ago on a Hidden Brain segment we called Stopwatch Science.

Some time ago, Dan and I were on a walk in Washington DC and he mentioned the work of a Stanford psychologist named Laura Carstensen. Dan isn't old, but he is an old soul. He's also an unusually generous human being. After hearing Laura explain the connections between age, wisdom, and generosity, it all makes sense to me now. Thank you, Dan.