How nature restores the mind

Welcome to Many Mines, a podcast about our world's spectacular varieties of mind and what we can learn from them. We feature conversations that shed light on the diverse ways of thinking, sensing and being that are out there. I'm your host, Kenzie Cooper-Eider, thanks for joining us. One afternoon, you decide to snub your responsibilities and go for a hike. You spend a few hours in the woods or the mountains. You study the bark of trees. You bathe in bird song. You let your eyes roam along a distant ridge line. And you come back feeling better, restored somehow, like you have more energy, more patience, more bandwidth. We've all, I'm guessing, had experiences like this. But what's behind these effects? Why would nature restore us? What's the evidence that it really does? And what is even being restored? My guest today is Dr. Mark Berman. Mark is an associate professor in the Department of Psychology at the University of Chicago, and the director of the Environmental Neuroscience Lab. Mark is also the author of a new book, Nature and the Mind, the science of how nature improves cognitive, physical, and social well-being. Here, Mark and I talk about attention restoration theory, the idea that nature experiences restore our limited capacity for directed attention. We discussed the broader field of environmental neuroscience, which Mark helped kickstart, and continues to lead. We range across studies from Mark's lab that show nature's beneficial effects on attention, on mood, and on health. We talk about what the active ingredients in nature seem to be. And we discussed the field's prospects for understanding how nature impacts not just the mind, but the brain itself. Along the way, Mark and I touch on soft versus harsh fascination, the elusive concept of mental energy, trees, wood, fire, and rain, the architect and theorist Christopher Alexander, the value of fake plants, fractalness in space and time, curvature and spirituality, and how nature tends to steer our thoughts in certain directions. Needless to say, we're stoked to be kicking off a new season of many minds. If you're new to the show, welcome. If you're already a fan, perhaps you'd consider leaving us a rating or review on your platform of choice. It really does help us reach new listeners. Alright, friends, onto my conversation with Dr. Mark Berman. Enjoy. Dr. Mark Berman. Welcome to many minds. Thanks for having me on the podcast. In your book, you lay out this distinction between things that provoke soft fascination and things that provoke harsh fascination. What is that distinction? When we think about soft fascination, we think about interesting stimulation that captures our involuntary attention, but it doesn't really consume all of our attentional resources, so that people can still mind-wander or think about other things. If I imagine a beautiful waterfall, it's interesting, it captures my involuntary attention, but I can still mind-wander and think about other things while I'm looking at the waterfall. If I think about harsh fascination, we think about stimulation that's also very interesting, but consumes all of our attentional resources. If you imagine walking through Times Square, there's a lot of interesting stimulation in Times Square, but it doesn't really allow for any reflection or mind-wander. The stimulation in Times Square is so strong, it's so kind of all-consuming. You can't really devote any attentional resources to anything else. We think that environments for them to be restorative of directed attention need to have this softly fascinating stimulation that tends to be in natural environments, but potentially walking through a museum that had a lot of beautiful artifacts or beautiful artwork, and if it wasn't too busy, it might have a similar kind of quality, so I kind of like to think of it as sort of interesting stimulation that's not so interesting that it's all consuming. I like this point you made that natural stimuli tend to have this softly fascinating quality, and man-made stimuli may tend to be a little bit more harshly fascinating, but it's not like that's an absolute right? You can also have natural stimuli that are a little bit harsher, right? I was thinking like maybe a bolt of lightning or something like that, right? Yeah, pretty hard to ignore. That's right. So you use this example, I like this example of the waterfall as kind of a paragon of soft fascination. Are there other ones that you think of as like especially good examples of softly fascinating stimuli? You could imagine a river where there's sort of rocks in the river, and you can see the river flowing. Maybe some leaves have fallen on the river, and you can watch the leaves moving on the river. I think of leaves also on trees if there's some wind, and you can see the leaves kind of swaying on the tree branches, watching a cardinal, you know, a bird flying around, landing on a tree. The same might be true of the sounds too, so it's very easy to think of sounds that are harshly fascinating, like, you know, a car alarm just going off this kind of repetitive sound versus like a bird song or the wind kind of rustling through the leaves that has a very different character than the car alarm. I had one that I was thinking of, which was just a wood fire that strikes me as this kind of endlessly softly fascinating kind of thing. Do you think that's a good example? Absolutely. I think of the great example. I was thinking about rain, too, in this context, like, I mean, I love the experience of sitting inside or on a porch or whatever, but watching and listening to the rain simultaneously, it's just like, I love it. Now, of course, you can saturate as it were on rain and a lot, you know, they haven't done research on it, but the sound machine company, you know, one of them is, is the rain. Of course, you're not getting the visual there, but I would say many people have the same experience as you where they like sitting on the porch and watching the rain and listening to the rain. And I think because it does have these softly fascinating characteristics. Yeah. So you already alluded to this distinction between involuntary attention and directed attention, which is another one that is really important for your work. Could you unpack that a little bit? We talk about attention kind of coming in two flavors. And this was kind of first proposed by one of my mentors, Steve Kaplan and his wife, Rachel Kaplan, when they were developing attention on restoration theory. So one kind of attention is called directed attention. I think other people might call it top-down attention or endogenous attention. That's the kind of attention where you as an individual person are deciding what you're going to pay attention to. And I think one of Steve's innovations with that was that the ability to direct attention he thought was fatigable or depletable that humans can only direct their attention for so long before they become mentally fatigued. And it's hard to focus. And, you know, I think we've all had that sensation that the end of a long work day where you might be staring at the computer screen and it's very hard to focus or direct your attention. That's the time to take the break. Directed attention fatigue can also be accompanied by irritability and lack of patience. These are all kind of telltale signs that you might be in a directed attention fatigue state. That's different from involuntary attention, which is the kind of attention that's automatically captured by interesting stimulation in the environment. And I think other psychologists might talk about involuntary attention as being bottom-up attention or exogenous attention that things in the environment are capturing your attention. And it's thought that involuntary attention is less fatigable or depletable. So you don't often hear people say, "Well, you know, looking at this beautiful waterfall is just really taxing and tiring. I can't look at it anymore." I can't watch this really interesting movie anymore. It's just too interesting. I have to shut it off. I'm getting too tired. So the idea behind attention restoration theory is that if you can find environments that don't place a lot of demands on directed attention while simultaneously having interesting stimulation that captures involuntary attention, you may be able to restore or replenish this kind of precious directed attention resource. And we think natural environments are one kind of environment that can do that. And then related to that was something we talked about previously as this idea of soft fascination. So we think that the kind of stimulation that activates involuntary attention needs to be softly fascinating and not harshly fascinating in order to restore directed attention. So I guess I'm wondering why, okay, if your directed attention is fatigued, that you wouldn't want to just jump to outright like sensory deprivation, you know, like full, full no input, nothing coming in as the best way of restoring that take of directed attention. Yeah, it's a good question. For one, we think that, you know, sitting in a dark room would probably be boring for most people and boredom is fatiguing. So I think that's part of it, that this is not a passive process. This restoration is still an active process. You're still engaging your cognition, but you're kind of doing it in a different way. You know, if you're, if you've got a really bad night's sleep the night before and you're really, really mentally fatigued, maybe taking a nap might be better than walking in nature. But This kind of mental fatigue that we're talking about is not like a. physical exhaustion. This is like, I'm just mentally not able to focus anymore. I can't concentrate anymore. And we think that this active process of being engaged with this natural stimulation can replenish this directed attention resource. So it's not complete rest per se, but it's not hard cognitive work either. It's this kind of, I might say, like a passively active process. Yeah, I was trying to think of the appropriate analogy here. And one that comes to mind is, you know, like in sports medicine, you'll often get prescribed active recovery, which is like, if you've overtaxed, you had a hard run or something. Rather than just outright rest, you'll often get prescribed something like, you know, a very gentle cardio, like maybe swimming or something like that. I don't actually know the mechanistic theory behind why that's better, but it sort of makes sense that you don't just want to have your body sort of collapse into total stillness. You want to give it a little bit of stimulation, keep things loose, keep things flowing, but just not so much that it actually additionally taxes. I think that's a fantastic analogy. I think that's a great analogy. So I think that, yes, I think that fits, that fits right in. And it, it doesn't replace. Sometimes you do need, yeah, exactly, exactly, but not all the time and, and you know, we do need sleep, right? But, but this is not like that. This is more like active brain recovery. Your work is part of this field of environmental neuroscience. You actually coined that term as far as I understand. I'm wondering if you could just say a little bit about what you see as the kind of scope of that subfield. I think of it as a pretty broad field and, you know, broader than just nature. I was kind of inspired by a few past psychologists and neuroscientists. One of them was Kurt Lewin, who has this, you know, kind of Lewin equation that human behavior is a function of the person and the environment. You know, that might not sound as prized to many people, but I do think a lot of psychology and neuroscience, even to this day is very focused on the person, the individual, and not really taking context or environment into account. And I think in psychology and neuroscience, too, when we do talk about context, I think we mostly talk about social context, but I think what we're doing in environmental neuroscience is also bringing in physical context, the actual physical environment that's around us can have an impact on our behavior, the architecture, maybe the noise levels, the temperature, you know, natural environments, but just anything in our physical environment, we think there are different elements that have a significant impact on our brain and behavior. Now, one thing that I wanted to take also from Lewin, Lewin, you know, started the Center for Group Dynamics at MIT, an engineering school. And I think Lewin was very interested in application. So he wanted to apply these concepts in the real world, but I also think Lewin was interested in really trying to quantify these relationships. And I'm also an engineer. And I'm, I really want to try to quantify these relationships. And in some ways, you know, maybe this is too grand of an idea, but I kind of almost want to try to make some of this work kind of like physics, where we could actually have equations, where we say, okay, if we expose people to this much fractalness and the environment, it will yield this much benefit to brain networks that underlie attention and cognitive functioning. So that's also a big angle here within environmental neuroscience. The other thing that I was really inspired by and with introduced to by Steve Kaplan was some of this early work by Donald Hab and Bill Greeno. So Donald Hab kind of anecdotally noticed that rodents that were pets learned a lot faster than rodents that were lab rodents in the laboratory. And he attributed that to how enriching the environment was. That rodents that were pets, you know, they're interacting with people more, maybe they had more toys to play with. The rodents that were in lab settings were in very sterile cages with not much in the environment. And that really struck me a lot too. That actually, you know, having these toys and different kind of structures in the physical environment could impact learning. And Greeno basically took that work to another level and showed that it actually changes the brains of these rodents, that rodents that have more enriched environments with toys, that have more social interactions with humans, but also other rodents. They have more glia cells in their brain. So, in fact, maybe in more synapses. So that was like very striking to me that the social but also physical alterations to the environment had direct impacts on the brain. So, patching this all together, I was just thinking we're really ignoring the physical environment like that everything in our physical environment is probably shaping our brains to some degree. And I don't think we're paying a lot of attention to that. And I think in part, we don't pay attention to that because humans, we have so much control over the physical environment. It seems like we're almost immune to the physical environment. We are dominant. We manipulate the physical environment to our will. But we haven't really designed the physical environment to like improve people's memory or improve people's self control or improve people's cooperation. We've designed the physical environment basically to move goods efficiently and to house people efficiently. So, I think what we're trying to do in environmental neuroscience is a look. We know so much now. Can we connect a lot of this seminal work in non-human animals to human as they look. This physical environment, these structures that we built are having a significant impact on our brains and our behavior. Let's pause for a minute and think how can we actually change the physical environment to sort of improve brain processing and human behavior. And I guess I would mention one other thing too about this is that there may also be individual differences. So, I think one thing too that we're looking into, we haven't really done a lot of it yet, but a thing that we're very interested in is that you can imagine that certain people are going to respond differently to different environments. So, we might be even able to tailor certain environments to different people given their physiology and their experiences. So, I think that's something else. You know, that may be a little bit of a of a dream right now, but it's something that as environmental neuroscientists were kind of aspiring to get to. So, yeah, so it sounds like this subfield has a pretty big scope in fact when you think about all the different aspects of the environment that end up shaping the human mind, the human brain. We'll be focusing today on, of course, the nature aspect of this, the subject of your new book, nature and the mind. And so, maybe we can start to dig a little bit deeper into some of your findings, some of your ideas in this area. It sounds like an important early influence on this work was attention restoration theory. Do you want to just say a word about what that is and how it sort of set the stage for some of your work? Yeah. So, one of my advisors in graduate school, Steve Kaplan and his wife, Rachel Kaplan, they composed this theory called attention restoration theory that basically you might be able to restore or replenish or even increase attentional capacity with interactions with nature. And I found that to be really fascinating because at the time when I was in grad school, a lot of people kind of thought that a lot of these cognitive capacities were traits and that they were fixed, that you couldn't really, you know, increase IQ or working memory capacity or attentional capacity that you're kind of born with what you have and that's it. And what Steve and Rachel were suggesting was that no, that's not true, that actually the different environments that were in could maybe even deplete our cognitive resources or improve or restore our cognitive resources. This idea, you know, that again, this critical element of attention restoration theory is the distinction between directed attention and involuntary attention, which I also thought was interesting. I kind of thought of directed attention almost as like mental energy. And I think in psychology and neuroscience, we haven't really found a good definition of what mental energy is. And so I kind of thought of directed attention almost as sort of like mental energy or kind of willpower to some extent. That was kind of attractive to me and that this idea that you could just have these brief interactions with natural environments that that could restore or replenish these very important cognitive resources like directed attention was was really, really interesting to me. And also, Steve would posit too that disability to direct attention. You know, it might seem very nuanced or maybe not quite as important as you might think about it first blush or first glance. You know, you might think, oh, you know, that relates to kids not being able to pay attention to school or yeah, I might, you know, mind wander at work, but it's not that big of a deal. But Steve thought disability direct attention actually underlied a lot of other cognitive functions like the ability to be goal directed, the ability to control impulses. Maybe it was also related to how aggressive people would be or how cooperative people would be. And when I started to think about this more, it kind of made a lot of sense to me. Like for example, being patient takes resources, not acting on your forced impulse takes resources. And thinking about directed attention as maybe being that resource was also very attractive to me. And I kind of liked that element of the theory. And I basically after learning about this in graduate school, I kind of met with Steve and I said, "Look, I really would like to test these ideas." And a lot of the research at the time in environmental psychology, they would do studies where they would send people in nature versus urban environments, but they didn't really use any objective measures. They would just kind of ask people, "Do you feel better in these environments?" And people would say, "Yes, I feel better," but they didn't really have these objective measures. One of my other advisors in graduate school, John Genitas, was a very eminent cognitive neuroscientist, you know, had a big tool kit in terms of different kind of cognitive measures that we could use to test whether interactions with nature did, in fact, improve objective cognitive performance. So the three of us kind of teamed together to design some of the first studies to see if interacting with nature did produce objective, quantifiable benefits to cognitive functioning. So yeah, maybe we can walk through some of the key findings of your work in this area. So I picked out three studies that I thought we could sort of zoom in on briefly. You cover, you know, many, many studies in your book. So these are not just like the three studies and of course, these have all been extended and replicated by other groups and so on, but just to get people a flavor of some of the work in this area. So the first one is what I think you refer to in the book as the Walk in the Park Study, published in 2008. Could you tell us a little bit about that? Yeah, so that was one of the first studies that we did to test attention restoration theory. Basically, what we did is we had participants come to the laboratory and our main dependent measure was this task called the backwards digit span task. So in this task, you would hear digits out loud at a pace of about one digit per second, like four, eight, three. And then you would need to repeat the digits back in backwards order. So three, eight, four. You know, at three digits, the task is relatively easy, but we keep increasing the number of digits up to nine digits. At around five digits, it gets really challenging. So we gave participants this backwards digit span task, and then we gave participants a map of a walking route. It was either the nature walking route was through the Ann Arbor Arboridum, which was near the University of Michigan campus, or the urban walk was through busy, wash, not avenue in Ann Arbor, Michigan. Both walks were 2.6 miles, and it took participants about 50 minutes, 50 minutes to do each walk. We also gave participants a GPS watch so that we could track them, but they didn't just go to Starbucks. We knew that they went on the walk, but also we tracked them so that we could see if they got lost or not. You know, did they actually go on the walk? Because we thought if people got lost, maybe the walk wouldn't be restorative. The last thing we did is that we took participants' cell phones. We didn't want participants to be chit chatting or texting while on the walk. We wanted to be very engaged with the environment. So we take your cell phones, we give you the GPS watch, we give you the map. You go on the walk, then you return back to the lab, and you repeat that backwards digit span task again to look for changes in performance. And then a week later, you return to the lab, you repeat the whole procedure again, but if you walked in the nature environment the first week, you walked in the urban environment the second week or vice versa. It was a within subject design, so everybody was their own control. And we had about 40 participants, and what we found was that people improved by about a digit and a half on the backwards digit span task after the walk in nature, but didn't really show any significant improvements after the walk in the urban environment. So they got about this 20% improvement on this backward digit span task after this brief walk in nature. So that was pretty impressive. We also gave people other measures, so we measured people's mood with the positive affect, negative affect scale. People's mood tended to improve after the walk in nature, but we didn't see much correlation between the mood improvements and the cognitive improvements. So we didn't think that we were getting these cognitive improvements just because we were putting people into good moods. And an even stronger demonstration of that is that sort of by design, but sort of by accident, we had people participants walk in these environments at different times of the year. So some participants walked in June when it would have been about 80 degrees Fahrenheit. In Ann Arbor, people really enjoyed the walk. They said, "Mark, I can't believe you're paying me to go for a walk." They showed healthy mood benefits, healthy backwards digit span benefits, but we also had people walk in January when it was about 25 degrees Fahrenheit. Others did not enjoy the nature walk, but they showed the same cognitive benefit as the people that walked in June. And that was really interesting because it suggested that to get these cognitive benefits, you don't even have to enjoy the nature interaction. Yeah. I think you use this line in the book, which I really like of. It just says you don't need to actually enjoy eating spinach to get the health benefits from spinach. You don't need to necessarily enjoy being in nature to get the benefits. So has that dissociation between the mood benefits and the cognitive benefits of nature? Has that been shown in other kind of thing that keeps popping up in other studies or does it sometimes depend on mood elevation? Sort of. I think there's some kind of interaction or there might be some minimum threshold of preference that you might need. So we did a study. This was with nature sounds. So we've done other studies where, instead of going for a walk in nature, we would play people 10 minutes of nature sounds versus 10 minutes of urban sounds. We again show improvements in different measures of working memory. For that study, we actually used the dual endback task and the dual endback task. You hear digits in your ears, like a flow of digits, like 5, 7, 9, 8. You need to respond whether, for example, the current digit that you're listening to matches the one that you heard two trials back. Oh, I see. While also simultaneously you're tracking a square that's moving around on a screen, and you need to say whether the location of the current square matches the location of two trials back. So it's a very challenging task. So we found that people's performance on that improved after listening to nature sounds versus urban sounds. We also had people do, I believe they did the backwards digit span task in that experiment too. And again, we showed improvements on that with the nature sounds. But these effects are not as strong as the real nature, but you can still get some positive benefits there through the sounds. So we've done some follow-up work, and this is with Steve Van Hedger, who was one of my former postdocs, he ran a study where he actually degraded the sounds. So almost like the fidelity of the sound wasn't as strong, so it sounded like you were hearing birdsong, but through a phone. Oh, OK, yeah. And people don't like those sounds as much, but we were still able to get some cognitive benefits from these degraded sounds. But my hunch is that if we degraded it a lot more, people really wouldn't like the sound, and I'm guessing we probably wouldn't get the benefit any more. And there have been other researchers that have found kind of some interactions where it's like maybe the more preferred nature might lead to slightly more benefits than the least preferred nature. I think it's an area that still is in active research. I would say kind of my takeaway message is that there's probably some minimum threshold for preference that you need, but that the whole effect is not driven by preference or mood. So yeah, if it were an outright aversive experience, and you probably wouldn't see these for sure, yeah, absolutely, yeah, absolutely. So I was going to ask whether you think that this like the 50 minutes, you know, because that's a pretty long walk, I mean, I sometimes go for walks that long, but not you can't always get away in the middle of the day for a walk that long, so I was curious whether you think you really need that, that length, but it sounds like if you see these effects with 10 minute exposure in the auditory domain, presumably you don't actually need the full 50 minutes, maybe you get more out of a 15 minute walk, but right. And you know, when we did the picture studies, or we've shown people nature videos versus urban videos, again, those are around 10 minutes and we do find positive effects. Again, not as strong as the walk, but they're still there. Other researchers like Ming Quo and Andrea Faber Taylor, they did studies with kids with ADHD. There they had the kids go for a 20 minute walk in nature, and they found benefits on attention for these kids. So we haven't yet charted out the full dose response kind of curve, like this amount of nature, at least of this amount of benefit, or you know, for example, what if it's like 10 minutes in Yosemite Valley versus 10 minutes in your local park, you know, again, there's a lot of research yet to be done. My kind of knee jerk response would be longer is probably better, but sometimes if it's too long, you know, you might get bored in the environment. So you want to make sure that you're maintaining that high level of soft fascination. If you're in the walk and you're like constantly looking at your walks, like I really don't have time for this walk, I don't think it's going to be beneficial. So I would recommend, you know, some people have talked about 20 minutes a day, or if you can get like two hours a week, that that would be kind of a good dose to try to shoot for. Interesting. Intuitively, to me anyway, it seems like it takes at least a little bit of time to shift gears in the sense of even let your mind actually start attending to the things around you as opposed to just chewing on whatever problem you are recently working with or battling in your work. I don't know how long it takes, but five minutes, 10 minutes to just kind of disengage from the old stuff. I think that says, you know, if we get into the nitty-gritty of attention restoration theory, Steve also posited a few more variables that might be important for the intervention to be restorative. So one of them is something that you're kind of alluding to, which is the idea of being away. So he thought it might be important that the nature environment that you go to give you a sense of being away from your day today. And I think that was, in some sense, to kind of break you out of your normal cycle that you could kind of be more captured by the stimulation in the environment. He also thought it was important that the environment have extent. So that there was enough stimulation there that would capture your involuntary attention. It had to be big enough. Now, that doesn't necessarily mean it has to be spatially big. Like, for example, Kensy, I don't know if you ever went to the garden of the Phoenix by-- I don't think so. Chicago. Jackson Park. So in Jackson Park, there's this small Japanese garden, the garden of the Phoenix, kind of right by the museum of science and industry. It's not a very big, you know, spatially, but it's got a lot of intricate things going on in the environment that capture your attention. Like, it's got these nice little bridges, it's got a waterfall, it's got this winding red clay path, I think that environment has extent, even though it's not very large. The other concept that you thought was important was that the intervention would be compatible with your goals. So if you have an exam in an hour and you haven't studied, it's probably better to study than to go for the walk in nature. So you kind of need to allow time for the walk for it to be compatible with your goals. Right. I'm still wrestling with this scale or extent, as you say. I'm sort of thinking of how within small spaces you can have just such a rich biodiversity, different textures and so on, that it's kind of endlessly engaging. There's sort of this trend, I don't know if it's, you'd say it's in forestry or landscape design or whatever, of these tiny forests, I think it started in Japan, but it's where you throw like, you know, an insane number of species altogether in a very small plot. And it turns out to be very-- well, it's claimed to be, I don't know if the studies are definitive yet, but it seems to be-- incredibly regenerative of the local ecosystem, to just have like a preposterous density of biodiversity in a small space. And I'd be curious whether those kinds of tiny forests would also be especially salubrious for humans and for the same reason that they offer so much extent in such a small space. I think so. I think that's very possible. And there could be a number of reasons for that. So it's possible too that if you're having so much biodiversity, it's probably going to be more softly fascinating, there's going to be more interesting things to look at. Then there also might be other elements too, like maybe the microbiota in that environment, you know, might be more diverse. We haven't gotten into this, but that could have cognitive benefits. As well, there have been other people that have shown that more bio-diverse environments are related to like lower rates of depression and lower anti-depressant use. So does that have to do with the visual aesthetic of the nature or something else? I think it's unclear, but there does seem to be pretty compelling evidence that having more biodiversity is a good thing, not just for physical health, but also for mental health. All right. So maybe we can talk about two other key studies that you've done. One is this study from 2012. That's a pretty close follow-on to the walk-in-the-park study. But focusing on people who are suffering from depression, could you say a little bit about that work? Yeah. So at the time, John Janidas had a big NIH grant looking at depression and we were looking at kind of working memory deficits in people with depression, seeing if like negative information and working memory might be more difficult for participants with depression to discard. And as we were doing these different studies, John and I thought, you know, maybe it might be interesting to see if interacting with nature would be beneficial for participants with clinical depression. And you know, at first blush, we weren't really sure because you could imagine if you're in a depressive state and you're ruminating about negative thoughts and feelings, going for a walk alone might exacerbate rumination and kind of worsen depression symptoms. So we designed a study that was very similar to that walk-in-the-park study, except with two differences. So one difference is that we did this study with participants with clinical depression. So we administered a structured clinical interview to see if they met criteria for depression. If they did, then we enrolled them in our study. The other change that we did is that we induced participants to ruminate on a negative thought in memory before they went on the walk. So before these participants went on the walk in nature, we had them write about and recall a negative thought or memory that was bothering them. And we did this because we actually wanted to induce rumination. But the dependent variable was the same as the original study of the same backwards digit span task. And we found something pretty incredible. The effect sizes were actually larger for this clinical population. So we saw even larger gains in backwards digit span performance for these participants walking in nature versus the urban walk. Another thing that we saw that was somewhat maybe surprising, it wasn't necessarily significant, but there was a trend where actually going on the urban walk actually reduced backwards digit span performance for some of these participants. And I don't know if that's because many times if you're in a roomative state, you don't really want to see other people and maybe going on the urban walk, we're seeing more people which might have been distressing, but it was kind of interesting to see that it wasn't just that the nature was boosting cognitive performance. It also seemed like there was some evidence that maybe interacting with the urban environment was actually worsening cognitive performance for these participants with clinical depression. And so here again, if I have it right, you also found that there was a separation, a dissociation between mood changes and the cognitive changes, is that right? Right, we didn't see a strong correlation between improvements in mood and improvements in the backwards digit span task. For this study, unfortunately, we didn't have the sample size to look at different time of year and things like that, but we didn't see any strong indication that it was driven by mood. We also asked participants, "Did you think about the problem that was bothering you on the walk?" And it didn't seem like the walk in nature lowered the propensity to think about these negative thoughts and feelings. What we think might be happening is that even if people are ruminating, the stimulation in nature could still capture involuntary tension and maybe give direct attention of reprieve. It's also interesting now, I don't know how evidence-based it is, but it's very interesting that now in the UK and in Canada, physicians will sometimes prescribe nature walks for patients who are suffering from anxiety and depression. So I don't think we're at a point now where we can replace other therapies for depression with walks in nature, but I think in terms of a supplement, it definitely seems like walking in nature might be quite beneficial for people suffering from depression and anxiety. You were of anyone who's tried to actually compare the sort of effect sizes of, say, regular nature walks with the effect sizes of cognitive behavioral therapy, because you can imagine doing a course of both and see how they play. Yeah, I haven't seen that. You're bringing up another thing that is important in this field, and I think we haven't really done a good job of it in part because it's difficult. But most of these studies are just single shot, one nature intervention. And sometimes you'll see meta-analyses that say, yes, nature, interactions with nature improve cognitive performance with the effect sizes are small, and I think, yes, but this is only like a 20 to 50 minute intervention on behaviors that people thought couldn't be changed. So I do think that we do need to start doing the really expensive studies where you have people interact with these environments on multiple days, weeks, months, and look at the cumulative effects. And to compare CBT to nature would require probably a very, you know, a lot more longitudinal kind of study. Okay, so maybe we can now talk about the third study I wanted to highlight, which is this study of green space of tree cover specifically in Toronto. Could you tell us about that work? So this was a kind of interesting study, maybe a little bit of a different study to do for a psychologist or a neuroscientist. But when I was a postdoc in Toronto, I got access to this data set called the Ontario Health Study that one of my collaborators, Thomas Powell, had access to. And this data set had health data for about 32,000 people in the greater Toronto area. And simultaneously, we found this really interesting tree data set. So the University of Toronto Forestry Department had a data set where they sent people out to catalog every single tree on public land. So these are like the trees on the easements, the easements like the little bit of land that's in between the sidewalk and the street. And they cataloged 580,000 trees in the greater Toronto area. We knew the species of each tree and the diameter of the tree at breast height. which gave like the age of the tree. And then one of my students, Omed Cardon, he looked at some forestry papers and basically calculated based on the tree species and the age of the tree, how much tree canopy each individual tree provided. So that gave us a good sense of like, how much public tree canopy was there in all these different neighborhoods in Toronto. We also had another data set with satellite imagery where we could quantify trees on private lands on people's backyards and things like that. So with these two data sets we could separate out tree canopy on public land versus tree canopy on private land. And then we basically just did a big regression to see what was the relationship between tree canopy and health. So we focused on cardiometabolic disorders as stroke, diabetes, and heart disease. And we found a 1% reduction in these cardiometabolic disorders was related to having 11 more trees of average size kind of on your city block. A 1% sounds pretty modest, but 11 trees is also pretty modest. And that was controlling for age, education, and income of the participants. To get that equivalent 1% decrease in cardiometabolic disorders monetarily, you'd have to give every household in that neighborhood about $20,000 and have them move to a neighborhood where the median income was about $20,000 more. Or it was also related to being one and a half years younger. So it's very hard to reduce cardiometabolic disorders. It's incredible. And this kind of speaks to cost. 11 trees on the street is probably cheaper than giving all the households $20,000. Making neighborhoods have a median income that's $20,000 wealthier, or making people younger. Now, of course, these are correlational data. So I can't make a strong causal claim. For example, a bad case scenario is just that, well, maybe healthier people choose to live in neighborhoods that have more trees. That may be true, but because we're controlling for age, education, income, those healthier people can't be younger, they can't be wealthier, they can't be more educated. So that makes me feel like I'm a little more confident in the direction of the effects, but I can't draw a strong causal relationship. The other thing that's interesting too is that we found the effect was larger for the trees on public land than on private land. And we think that's because the public trees, maybe everybody in the neighborhood kind of has access to those trees. The trees and people's backyards are in private land. You don't have as much access to them and therefore they might not be having as big an effect. I can't help but wonder whether, one way of reading this study is that trees are just a proxy for nature in general, right? But I can't help but wonder whether there is actually something psychologically, especially potent about trees. Do you ever, do you think about that? Yeah, so it's really interesting. So I think a natural question is, okay, why are the trees having this effect on cardiometabolic disorders? You know, one obvious one might be, well, maybe it's improved air quality. It's actually beneficial for cardiometabolic disorders. It could also be the case that if you have more trees on the street, maybe it encourages people to go outside and maybe walk more and be out in the environment more. So maybe people might exercise more. But you bring up this other point, which is that is there something about the aesthetic of nature, the fractalness, the curved edge structure, the color palette, that maybe our brains process more efficiently and therefore could that lead to health benefits that sounds crazy, but it might be true. And a study that kind of relates to this is a study by Roger Ulrich that he did in the 1980s, looking at a single hospital corridor in a hospital in Philadelphia. So one wing, one hallway and this hospital in Philadelphia, in some of the rooms, some of the patient rooms, had views of modest nature, like some trees, some grass, some shrub. Other rooms on this corridor had views of like a brick wall, like the other side of the hospital. And Roger was interested to see if these views might impact recovery from gallbladder surgery. And it turned out that patients recovering from gallbladder surgery, if they had the view of nature, they recovered a day earlier and they used less pain medication than the patients that were in the rooms with the view of the brick wall. And what's interesting about these studies is that it was sort of a quasi-experiment because patients are just randomly assigned to the different rooms, so they didn't have choice. So it wasn't like more educated or younger patients got the rooms of nature and less healthy patients, got the rooms with the brick wall. No, patients are randomly assigned to these different rooms. And the room had this significant impact on healing, on recovery. I don't think those effects are driven by air quality. Yeah, I don't think they're driven by exercise. There's something about the aesthetic of nature. Now maybe it was too, maybe it was like, it's just more pleasant, maybe to be in those rooms and maybe that had some healing element to it, but it's very interesting to think about that, that maybe just the aesthetic of nature could have a healing quality. On the tree points specifically, I'll throw out an extremely speculative idea that I've had for a while now, which is at some level, I think people anthropomorphized trees treat them as human-like beings. And in particular, when you get a tree of a certain size such that you're under its canopy, I feel like it has to call to mind. Again, at some psychological level, I'm not saying anyone's consciously aware of this, but call to mind the experience of being loomed over by an adult figure, by a parent, by a nurturing figure or something like that. So we feel kind of naturally protected. I mean, you can see this in the way that people talk about trees being human-like as being father figures, mother figures, these kinds of metaphors are very common. And I wonder if part of what we see in trees is this source of sturdy adult comfort. Anyway, and a speculation, but. I mean, I think that's possible. You know, there's other studies too. These are actually studies done in Chicago by Mingguo, Andrea Faber Taylor, and Bill Sullivan, where they looked at public housing projects in Chicago, like the Robert Taylor Homes or the Ida B. Wells Public Housing Facility. And they looked at the views out the windows of these different apartments in these public housing facilities. Some had more nature, like some trees and shrubs and others had no nature, like views of asphalt or concrete or brick walls. And again, like the Aldrich study, these families are randomly assigned to these different apartments, so they don't have control over that. So again, it's not like more educated or wealthier families get the better nature views. And it turns out that kids living in these different apartments if the kids have the views of nature, they have better attention. They have better self-control, self-regulation. In the adults, the adults have better attention. The adults have less aggression. There's actually less reported crimes in the apartments that have more green space around them. You know, you might be thinking, well, okay, yeah, does this tree have this kind of looming adult figure somebody watching, but then I also kind of wonder why would that improve people's attention? You know, so, and again, you know, with all these things, I think it's complicated. There might be many, many different mechanisms and things that happen. I don't think it's just one thing, but it's amazing. And, you know, again, what you kind of mentioned too, I even, in talking to me in Quill and Bill Sullivan about this, it's not like the people that had the nature views were staring out the window all day long, or I'm not even sure they really were aware of, and this is what was out there of their window, and yet it had this significant impact on behavior. So not to say, you know, aggression and crime are very, very complicated problems. I don't think if we just plant a bunch of trees, we're gonna solve these problems, but, you know, the physical environment does seem to have a significant impact on our behavior, and there does seem to be something special about trees in a natural environment that can improve human well-being and human cognitive functioning. Okay, so maybe we can dig a little bit into what you learned about what it is in nature, what it is in natural, stimuli natural experiences that seems to be driving these salutary effects. So you've tried to get at this various ways. How do you now think about sort of like, what the active ingredients are, if you like, of nature? It's still a work in progress. We're still trying to do a lot, and different ingredients might impact different sort of outcomes. So maybe I'll first start a little bit with some of the cognitive outcomes, and a lot of psychologists and neuroscientists might not really be satisfied with some of the kinds of a soft fascination that maybe that still just seems not, there's not enough meat on the bone there potentially. So we're trying now to sort of quantify what soft fascination might mean in more quantifiable ways. So one project that I've been working on with one of my students, Nakwan Ren, is to see if we can sort of measure how effortful it is to process natural stimulation, or in fact, how much energy it might take to process natural stimulation versus urban stimulation. And one idea that came to mind for us was this idea of JPEG compression. So JPEG compression is an algorithm that our computers run and that our phones run to try to save memory. So what JPEG compression does, basically, is it takes an image that might be high resolution and tries to lower the resolution, oftentimes by removing a lot of the high frequency content in the image that maybe our eyes can't really detect, and so now that takes up fewer bits on the computer. We don't notice that the image looked the same, but it actually has less information than it had at high resolution. So one thing that we wondered was whether nature stimulation might be more JPEG compressible than urban stimulation, and sure enough it is. More natural images get compressed down into fewer bits than urban images. Does that mean our brains are doing that for say, not necessarily, but it's possible. Another related research project that we have, so one of my colleagues, Wilma Bainbridge, was very interested in memorability, what makes a stimulus memorable? And she finds that there are some stimuli, like some faces, some objects, some artwork that are just inherently more memorable than other objects. So we wondered, are nature stimuli, do they differ in their memorability compared to urban stimuli? And it turns out that urban stimuli are better remembered than nature stimuli. Okay, that might seem negative at first glance. That seems bad that you don't remember the nature stimulation, but we think it's actually a good thing. We think that means that actually the nature stimulation is not getting processed with the same depth or the same effort that it takes for an urban image. So the nature image is kind of flow through and doesn't stick, whereas the urban stimulation is more sticky, and that might mean that it's more taxing the process, and to put those two findings together, it turns out that one of the reasons why nature stimulation is more forgettable is because it's more compressible. So the compression thing partially mediates the memorability effect. So that's pretty neat. So that's part of the reason why we think maybe looking at nature might be beneficial. Well, to then say why this is more complicated, like the most compressible thing would be just looking at a black screen. That's very compressible, and I don't think looking at a black screen is going to be restorative. So again, there still must be some amount of processing that needs to happen, but at least in terms of regular scenes, more natural scenes are more compressible, and they're more forgettable, and we think that might be one of the reasons why they're less cognitively taxing, and therefore might restore directed attention. And this goes back to the sensory deprivation idea we were talking about earlier, like the black screen, the complete absence of stimulation would not necessarily do the same thing. That's right. Some minimal complexity. That's right. So like most things in nature biology, it's got to be nonlinear. So if you have too little information, that's probably not good, too much information. That's probably overwhelming. Maybe nature sits, natural stimulation sits at this right nexus of having enough information, but not too much information. So I guess analyzing images of natural scenes, you've pulled out some of the visual features that are particularly characteristic of natural scenes. I think you mentioned some of these already, but just to go through them. Yeah. So some of the first things that we started to do was to say, okay, can we train a machine learning algorithm to predict a naturalness score on an image? To see like our people using common features to determine whether an image looks natural or not. So again, this has worked that I did with Omid Cardan, who was an electrical engineer, so he knew a lot about image processing and signal processing. So we quantified a bunch of different features in these images. One thing that we did was actually quantify all the edges. So we quantified all the curved edges and straight lines in an image. And it turns out this isn't going to be too surprising, but if an image has more curved edges and less straight lines, people rate those images as being more natural. You know, if you imagine like a tree has a lot of curved edge structure, grass has curved edge structure. If you think about water with ripples, that has curved edge structure, but a building, especially if it's got like brutalist architecture, doesn't have a lot of curved edge structure. Fractalness, how fractal the image is, is also indicative of how natural it is. So if we talk about fractals spatially, so you imagine like a snowflake, a snowflake has a characteristic shape. If you put that snowflake under a microscope and zoom in, you can see some of that same shape. And if you zoom in again, you can see some of that same shape. So it doesn't matter what spatial scale you look at the snowflake, it kind of has the same or similar characteristic shape. So that said that the snowflake is sort of scale-free. It doesn't matter what scale you look at the snowflake. People also call that fractal, that the snowflake is more fractal. And natural stimulation tends to be more fractal. So a tree has a trunk that branches out into big branches, that branches out into smaller branches, that branches out to leaves, the veins in the leaves branch out. This branching pattern is seen in all of these different spatial scales of the tree. In some sense, it doesn't matter as much at what spatial scale you look at the tree, it's got the same pattern. That is different than the urban environment. The urban environment is not at scale-free. The urban environment changes a lot, depending on the spatial scale that you look at. And then the color palettes are different between natural scenes and urban scenes. So the takeaway message is just using these low-level visual features, you can predict how natural a person will think a scene is with like 90% accuracy. Interestingly too, you can also predict how much people will like a scene based on these low-level visual features. And people tend to like images that are more fractal and that have more curved edge structure, that have more symmetry. You can predict how disorderly or orderly somebody will think a scene is, just based on these low-level visual features. We haven't yet tested, okay, let's take nature that has more curved edge structure versus left curved edge structure and see which one will improve cognitive performance more. That's kind of something we're kind of interested in doing. If we take a step back and not just think about cognitive performance or preference, we had an interesting collaboration with a private foundation called the TKF Foundation, now it's called Nature's Sacred. And this was a foundation that built about 150 parks on the east coast, mostly in Baltimore, Washington, DC, and inapolis, Maryland. And this foundation did something interesting. At each one of the parks that they built, they had a characteristic bench, this wooden bench. And under the bench was a journal that people could write in. So this foundation had collected about 12,000 journal entries of people sitting in parks, just writing down their thoughts. So one of my students caked shirts with interested in seeing what do people write about when they're in nature. And so she did a topic modeling analysis and found some of the topics that people wrote about in these parks. And then we also had pictures of these parks where we could quantify some of the different low-level visual features like how much curved edge structure is in the park. And then we had another set of participants. We showed them these pictures of these parks and had them give a naturalness score to these pictures of these parks. So the first analysis that we did was kind of a sanity check. And we basically said, okay, if the park was rated as being more natural, do people write more about topics related to naturalness? And yes, we found that if the park was more natural, people tended to write more about topics related to naturalness. Okay, that was a good sanity check. But then it got kind of weird and interesting. So Kate found this correlation that if the park had more curved edge structure in it, more curved edges, people wrote more about topics related to spirituality in their life journey. That was kind of interesting. But that was just correlational. Maybe these parks were in different locations. Some of them were near hospitals or near places of worship. Maybe it just so happened that the parks with more curved edges happened to be near places of worship or in hospital. So maybe that's why people were thinking about spirituality in their life journey. So then Kate designed an experiment where basically she found images that might be equal in naturalness. But one might have more curved edges than the other or two images that might have the same urbanness. So they're both urban images. But one image has more curved edges than the other. And then we ran a study online where we showed people a single image and had different thought clouds about different thoughts and said, "We want you to pick the topic or thought cloud that goes best with this image." And it turns out that if the image had more curved edges in it, people were more likely to select the topic of spirituality in their life journey. Like one and a half times more likely. Okay, that was pretty wild. Then it gets even wilder. Because maybe for some of the images to remove the curved edges, maybe had to get more water into the scene. And so maybe there's just something like seeing water you don't think about spirituality in your life journey. I don't really believe that, but maybe that's possible. So what Kate did is she scrambled the images so it had all of the curved edges, but you couldn't really tell what it was anymore. So then she repeated that same experiment where you'd be shown this image, it kind of looks like a Jackson Pollock painting. And you have the thought clouds that go below and you pick which thought cloud goes with the image. Well, it turns out even in these abstract images that don't, we've removed the semantics. If the image had more curved edge structure, people were more likely to say the image went with spirituality and their life journey. So there's something about processing these curved edges that sort of got people thinking about spirituality and life journey. You know, I don't know if there's something about metaphors about if your life journey like this curvy path or something like that, but it was a very, very interesting effect that we got. I love this study because there's kind of this whole dimension of this that, as far as I understand, remains to be mostly explored, which is like how does nature, being in nature, natural experiences, how does it shape our thoughts? It may have these cognitive benefits, these health benefits, but at some level, a big part of what it's doing has to be that it just directs our thoughts in certain ways or nudges us to think about certain things or gives us certain kinds of ideas. And so this study provides us a first demonstration of exactly that point. I don't know if you would have come across this study, but it reminds me of this influential paper in PNAS some years ago, maybe 10 years ago at this point, about firelight talk among a hunter-gatherer group in Africa, I forget which one. But basically, the anthropologist was doing an analysis of the kinds of things people tend to talk about in their day-to-day activities, chores, walks versus the kinds of things they tend to talk about when they're sitting around the fire at night in a social group. And found that being around a fire at night just lends itself to a really different set of topics. And so I was thinking about exactly that kind of thing. I mean, obviously, that's looking at conversation, so it's maybe a little different, but does being out in nature just lead you to entertain certain kinds of ideas, steer your mind in certain predictable directions. I mean, you could look at it with conversation too. I love, personally, having a walk with someone in nature is one of my favorite forms of conversation, right? Like, it always feels like there's something about those conversations that gets a little deeper. Yeah, it's a great question. And Kate and I did some studies related to this, so we did a study at the Garfield Conservatory, which is a really nice indoor conservatory with a lot of nature. And we looked at Water Tower Mall, which is kind of a fancy mall in downtown Chicago. And what we did is we bust participants to these different locations and we gave them cell phones that would then ping people while they were in the environment to ask them, what are they thinking about? And it turns out when people were in the conservatory, they tended to think less about themselves and more about other people being in the conservatory. They tended to think more about the past than the future. Their thoughts tended to be more positive and reflective. When they were in the mall, they tended to have thoughts that were more impulsive, which might be what the mall designers are getting at. But it was really interesting to me that people thought more about other people and less about themselves and thought more about the past. So yeah, I do think that being in these environments also changes what people think about, or the kinds of things that people think about. If we go back to the ideas about nature being more compressible, we've also been thinking about language that maybe in our vocabulary, we don't have a lot of words for nature. I can say tree, grass, shrub, but when I'm in the urban environment, I can say Volkswagen Beetle, you know, Gothic architecture, you know, there's just the vocabulary is so much rich. There may be so many more kinds of objects that you might be just very busy kind of cataloging all of the objects and there's not room to really think about anything else. Interesting, interesting. So that's kind of another thing that we've been trying to think about is like, is nature less semantically complex than urban? Now what would be interesting too is that if you have different cultures or different populations of different environment, maybe they have a larger vocabulary for nature, you know, would nature have a similar impact or not, you know, that would be very interesting to look at. There's this study that you may have come across where they basically did a historical analysis of how English speakers talked about the natural world over time and they found that I believe there was an inflection point in the 19th century in the late 1800s where people in literature basically just stopped talking about oaks and maples and elms and just started using tree as the generic. And now, I mean, when you're like, if you're a kid growing up in somebody like I did, I knew that oak was a word for a tree, obviously, but I wouldn't have been able to tell an oak from an elm from a whatever. So there was kind of an interesting historical shift at some point in this, it seems. I actually appreciated how in your book, because I've become somewhat of a tree nerd, I appreciated how you, when you mentioned trees, you mentioned specific, you know, sugar magnolia and blue spruce and these kinds of specific kinds of trees, not just tree, which is mostly what you get in English descriptions these days. But I imagine the same kind of trajectory could be observed in other aspects of the natural world, birds. I would bet that now, in literature, people just say a bird flew by rather than, you know, a kestrel or whatever it is. Right. I'm wondering if we could talk a little bit more. We've already touched on this a tiny bit, but a little bit more about design and architecture because in that world, they've been thinking about nature for a long time, at least some folks have. They've been thinking about how to introduce natural elements into the built world. One of the folks you mentioned in that sphere, who I've always been interested in as this architect, Christopher Alexander, and he had some ideas about this, could you say a word about him? I didn't really know about his work until I was introduced to Christopher Alexander from this one collaborator of ours, Alex Coburn. So Alex Coburn at the time was an architecture PhD student at Cambridge. And he was kind of interested in natural elements in the built environment, and he came across our research, and he wanted to collaborate. And he introduced me to Christopher Alexander, who I would say was someone who was very, very interested in kind of mimicking the patterns of nature in the built environment. And he kind of laid out all these different principles of good design that would try to mimic many of the patterns in nature, one kind of being fractalness or levels of contrast, and different kinds of symmetry and organization that also mirrored a lot of patterns in architecture. And so what we did with Alex Coburn is we kind of tried to test some of Alexander's principles, through people really like these principles, and can people kind of see nature in the built environment. So in one of the first studies that we did, we showed people different architecture scenes, like building façades or building interiors. And all participants had to do, they were showing about 12 or 15 of these scenes on a large computer screen. And they just needed to move the pictures around on the screen to lump the pictures that were more similar together, and if they thought images were very dissimilar, kind of put them far apart. And by doing this procedure, we basically got a similarity matrix for each person, for how similar or different they thought all of these different images were from one another. And then we could do a statistical analysis called multidimensional scaling to try to see where there are dimensions that explain the most variability in these dissimilarity ratings. And then what we did is we had another group of participants rate all these images again on how natural they thought they were or built, but again, these were all built images. So there wasn't any real nature in them, but people still had variability there. And what was really interesting was that the first dimension that we found that explained the most variance in these similarity judgments was like a naturalness dimension. So images that had more fractal structure, more level of contrast, more curved edges were kind of all grouped together, and kind of buildings that were more sterile that had more of the brutalist architecture were on another side. So it was kind of interesting that even though when these participants were moving these images around, we weren't imposing them to think about nature, but yet implicitly, they were kind of thinking about nature. And if you are familiar with, you know, Gaudi's buildings in Barcelona, you know, Gaudi is mimicking the patterns of nature in his buildings. Like let's engrave a familiar that big cathedral, it almost looks like trees are rolling out of it. So there's a lot of, he's mimicking a lot of patterns in nature there, and people really like that kind of architecture. And they think of it as being more natural than the more brutalist kind of architecture. And the same could be said to like the buildings on the University of Chicago campus, this gothic architecture that has a lot of intricacy, people they like it more, they prefer, and they actually find it to be more natural than the kind of more modern boxy, you know, architecture. Again, we don't know yet if you can get cognitive benefits from that kind of architecture. I think it's possible, you know, in my book, we have this kind of very boring image, [BLANK_AUDIO] image of two doors. Oh yeah, yeah. You know, one door has like some molding and then some rectangles in in the door itself and the and the door itself as a rectangle. So it actually has this fractal structure versus a door that's just plain. People do not like that plain door frame and they don't see it as being natural. So even something maybe as benign as a door, you might be able to elicit some of these feelings, maybe even some of these cognitive benefits from from doing different things with design. So so we're very interested in, and you know, now I'm kind of speculating more, but trying to incorporate more nature into our interior spaces into the built environment to try to mimic these natural patterns that we think might have cognitive and mental health benefits. Yeah, no, I love that little bit about the doors because it does. You're right, it look at first blush, it's like, wow, this is a boring figure. But then when you actually start to think about you're like, wait, I've seen doors like this. And yeah, there is something off putting about this plain door and that there's something that I do find appealing about this more, you know, maybe it's a little more detailed and ornate and maybe it looks needlessly so in some sense. But then when you look at it, you're like, no, I strongly prefer this door with this patterning to it. Right. One thing that I don't think you touched on in your book that I've always been curious about is the use of wood as a material in particularly an interior spaces because like, when you have wood, like you know, my desk, great that I'm sitting there right now is wood and the grain itself has a lot of these properties of organic natural materials, the curvature fractals as you're saying it has this softly fascinating aspect to it. And I personally have always felt drawn to spaces that have a lot of wood in the interior. I mean, you could argue, but you could overdo it a little bit or whatever. But there's something psychologically appealing about it. I'm just curious whether that's an element of this that you've thought about her. Yeah, absolutely. So again, we haven't really tested that yet, but I'm very much in agreement with your intuition that wood, you know, wood furnishings, they obviously mimics the patterns of nature. I think people find it soothing. I think they find it softly fascinating. I think there could be benefits to it. I, you know, there are some lecture rooms, for example, in the University of Chicago that have some wood beams in the lecture hall. I kind of wonder like our students paying attention better in these rooms that have some of that characteristics. So I absolutely, I think that's one way again, too, to kind of natureize these indoor spaces is to use wood. And like you said, you can kind of get too extreme. And I've seen studies too where they would bring like plants into the indoors and like how much of the indoor should be covered in plants. And when about 15 to 20% of the space was covered in plants, people liked it. If it got more than that, it seemed a bit too chaotic. And I say too saturated. So, so more even always better. I would say more is better, you know, for going out in real nature, but in terms of our interior spaces, maybe you don't want to overdo it, but definitely bringing in natural elements to all of our build spaces would likely have benefits. So maybe we can start to kind of zoom out here and talk about some some bigger picture things. One thing that I was wondering throughout your book and we've maybe touched on a little bit is this idea of dosage. If you're thinking about trying to incorporate more time and nature in your life, time and natural spaces into your life, is there some added benefit to having like a long immersive experience or is just little hits of nature throughout the day fine? I'm kind of thinking here about a parallel discussion that you sometimes hear in like meditation circles, where people will weigh like, okay, is it better to have the seven day silent retreat or to just have a couple more minutes a day in your daily meditation practice, that kind of thing? And I'm actually not sure where people have come down, but I've heard people advocate for know that the it's better to just have a long silent retreat. You really need that full immersion to reset your attention. I'm just curious if you have any thoughts about that same question when it comes to nature experience. Yeah, it's a great question and unfortunately I don't, I can't give a strong answer because we haven't really tested it and I don't know if any other series have really tested it. I would say you definitely want to get consistent dosing, you want to get nature interactions pretty regularly. I wouldn't say he want to just take the one trip to Yosemite and that's it and not getting nature the rest of the year. I think you kind of want to do both things. So on the work week, maybe you can't get a 50 minute walk in nature, maybe you can only get a 10 minute walk in nature, maybe you can only look at some nature pictures or listen to some nature sounds, but maybe on the weekend you can go and spend an hour in nature. So you know, I would recommend that. Again, I would recommend changing your spaces like, for example, behind me, I can't really grow plants in my office. I don't have enough sunlight here, but I've got some fake plants in my office. It's also thinking about like designing your day. So I try sometimes to leave some space in the afternoon where I can go and walk in nature and spend some time in nature. Thinking about where you're going vacation. So we definitely try to do a lot of our vacations out out in nature. I like to get my kids out in nature, but I don't consider that a restful time for me. That's for them. I have to carve out different time for me. But I think, you know, Rachel Kaplan used to talk a lot of micro doses that you want to have these micro doses of nature. So I think that's kind of the first step is to get some real or fake nature into your living spaces and work spaces. And then I think it's really important to try to design in nature breaks during the work day and definitely on the weekend. I haven't studied this. This is only my intuition, but I get a little nervous sometimes where I hear about schools taking away recess because especially if you're getting some recess time and it's out in nature, that could really help student learning and, you know, imagine a scenario where you're comparing eight hours of instruction versus six hours of instruction and two hours for students to have a break in nature. I do think it's possible that students might learn more with less instruction, the six hour of instruction and two hours of the nature break than from the eight hours of continuous instruction. So this is, again, goes back to costs and benefits and long-term costs and benefits. You know, it might seem like, wow, we don't want to shorten the work day or we don't want to shorten the school day. That just seems like it's going to be less productive and people are not going to get as much done. But what if it's possible that again, if you if you gave people the right break and if we actually designed environments where it was easier to get breaks in nature, you know, maybe you would get more productivity from less time actually. So, you know, with the book too, I do want people to start thinking about these things more seriously that this isn't just an amenity. This is a necessity that it's kind of like exercise, eating your vegetables, interacting with the nature is another thing we need to add to our menu of things that we kind of have to do if we want to be our best selves. And in a lot of cases, we enjoy the time in nature more than we might enjoy the interval workout or whatever that we think we're doing for our health. So maybe if it's pitched in the right way, it will be such a such a hard sell. Well, that's an interesting thing too is that John Zaleski and I think Elizabeth is but they did a study that was published in psych science where it was like effective forecasting. So, it was like they asked a group of participants, how much do you think you would enjoy a walk in nature before they went on the walk? And then they had another group of participants where they asked and how much would they like the walk in nature after they went on the walk? And it turns out people really underestimated how much they would like to walk in nature. That's probably pretty common for all of us that we're underestimating how much we're going to like the nature and then I would definitely think we're underestimating how good the nature walk will be for our psychological well-being. All right, so we've touched on a number of kind of open questions, possible future directions. I wonder if as we're closing here, you could just flag a couple of the future directions for environmental neuroscience that you're most excited about right now. I think one thing I'm really excited about, so you know, we haven't really talked about any neuroscience yet right now. And there's a reason for that. So I'm also, you know, published a lot with brain imaging and using FMRI to understand different cognitive processes, but I haven't yet merged some of this nature research with neuroimaging, which would be like really what we're what we want to study in environmental neuroscience. And part of that is because it's it's difficult. So, you know, if you've ever been an MRI scanner, it's a very narrow tube that you're in. You got claustrophobia. You can't be in there. It's uncomfortable. You can't move your head. It's very noisy. I don't think we can really give people a nice natural experience in the MRI scanner. It's interesting now there's starting to be new technology or relatively new technology that allows for mobile brain imaging. So one of these technologies is called function near infrared spectroscopy, which is this little cap that people can wear that shines infrared light into the brain. And you can measure oxygenated and deoxygenated hemoglobin, kind of similar to the blood-oxygenated level dependent signal that you get with FMRI. So now we're studying to do studies where we're going to actually, we're sending people on walks and more natural environment. Send any of you on walks and we're urban. and actually monitoring brain activity when they're in these different environments. Now you might be thinking, okay, what are you, what are you looking for in the brain? And this actually relates to another line of research that we do in a lab where, again, I'm very interested in kind of mental energy. And one of the ways that we've quantified mental energy or cognitive effort in the brain is using a nonlinear dynamics measure that's related to fractalness. Now when I talked about the snowflake, I was talking about fractalness in space that the snowflake has these repeated patterns spatially at different spatial scales. But you can also look at fractalness in time. So you can have a brain signal that's oscillating in time and you can basically say, how similar is that signal at one second, five seconds, ten seconds, thirty seconds, an hour? Does a signal look the same at these different temporal scales or different? And it turns out a signal that looks very similar at these different temporal windows is thought to be fractal or scale free in time. We've found that when you're learning a new task versus being very well practiced at the task, the brain is less fractal when you're learning the task versus when you're well-practiced at it. If you're trying to remember two things, versus four things, versus six things, the brain is more fractal trying to remember two things and less fractal of four things and less fractal at six things. As we age, if we equate for cognitive performance, the brain is less fractal for older adults versus younger adults. How fractal the brain is predicts whether kids have higher or lower psychopathology and even how fractal the brain is predicts how much you're going to improve on a task. If the brain is more fractal, you're more like to improve on a task. And even we find that how fractal the brain is at age nine predicts cognitive performance two years later. So we think all of this is suggesting that when the brain is in this higher fractal state in time, it's exerting less cognitive effort. And maybe it almost represents this like critical state. So if you imagine a water molecule at a certain temperature, pressure, it can kind of more easily transition into a gas, a liquid, or a solid with very little energy. Well, maybe when our brain is sort of at this really fractal state, it can more easily transition into other state. So now we're wondering, "Okay, when you walk in nature, is the brain sort of more fractal in time than the walk in the urban environment?" So that's something that we're really, really excited to look into. Awesome, that sounds great. Yeah, I mean, this is definitely a question that has been lurking in the back of my mind throughout your book and throughout this discussion of like, how would we cash out some of these ideas of, you know, directed attention fatigue, soft fascination in terms of actual brain states? Presumably, there are some brain states, there are properties of the brain there, but it would be awesome to get more purchase on that. Yeah. All right, so we'll be pointing listeners to your new book, which I recommend to a bunch of the studies we've been discussing. There's a number of cool directions that your lab has taken that we didn't really touch on. But for anyone who wants to read even more broadly, you know, maybe look at the work of some other researchers, do you have any particular readings you would point them to? Greg Bratman has a really interesting paper in science advances talking about the olfactory system and maybe like the smells of nature and maybe how some of these effects might be related to olfaction. So I think that's pretty interesting. Kim Dole has a paper in nature climate change that I think is pretty interesting about, I'm actually a co-author on that paper, we're kind of looking at like with climate change and nature sort of changing what is going to be that impact on our brains. And then I'm missing out on the author, but there's been a recent meta-analysis about some of these nature effects trying to understand when might you get like the most bang for your buck cognitively from these nature interactions and maybe you have to have like a 30 minute exposure to get like the most bang for your buck. All right, Mark Burman, this has been a lot of fun. Thank you so much for taking the time. Thank you. Thank you for having me. It was a lot of fun. The Many Minds Podcast is a project of the Diverse Intelligence Summer Institute, which is made possible by a generous grant from the John Templeton Foundation to Indiana University. I'm Kenzie Cooper-Oiter. Thanks so much for listening.