How Nature & Other Physical Environments Impact Your Focus, Cognition & Health | Dr. Marc Berman

0:00 Welcome to the Hubberman Lab podcast, where we discuss science and science-based tools for everyday life. I'm Andrew Huberman and I'm a professor of neurobiology and opthalmology at Stanford School of Medicine. My guest today is Dr. Mark Berman. Dr. Mark Burman is a professor of psychology at the University of Chicago where he directs the environmental neuroscience laboratory. His research focuses on how our physical environments, particularly natural environments, impact our brain function, mental health, and cognitive performance. During today's episode, we discussed the fascinating and actionable science of how your physical surroundings indoors and in particular your relationship and interactions with nature can shape your biology and your cognitive abilities. Dr. Burman explains how exposure to very common features in

0:46 nature such as fractal patterns, increase your ability to focus, reduce your stress, and improve your mental and physical health metrics. and not just while you're in nature, but after you return indoors for many hours and even days afterwards. During today's episode, you'll learn about something called attention restoration theory, which turns out to be very important for understanding how different types of indoor and outdoor environments either deplete or restore your cognitive resources. We also discuss practical science-based strategies that anyone can implement regardless of where you live. So, if you're in an apartment or a house, if you have ready access to nature or if you don't, today's episode explains how to design your indoor space, the optimal duration and timing of nature exposure, and the specific visual and auditory elements that will provide you with the greatest cognitive and health benefits. So whether you're a student or a professional looking to

1:31 enhance your learning capacity, focus, and reduce your burnout, or you're simply interested in optimizing your mental and physical health through exposure to different elements of nature, today's episode provides clear, actionable protocols based on rigorous scientific research. By the end of today's episode, you'll have a toolkit of evidence-based strategies that will transform your relationship with your indoor environment and outdoor environments, and you'll learn to harness those to improve your brain and body. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is however part of my desire and effort to bring zero cost to consumer information about science and science related tools to the general public. In keeping with that theme, today's episode does include sponsors. And now for my discussion with Dr. Mark Berman. Dr. Mark Berman, welcome.

2:17 Great to be here, Andrew. I love being out in nature. So, I'm excited about today's conversation, which is taking place indoors. But we're going to talk about the relationship between the mind, the brain, nature, stress, rumination, and this incredible power that interactions with the natural world can have on our brain. As we wait into this, I'd like to start with this issue of recapturing our attentional abilities because I think nowadays everybody, whether they're clinically diagnosed with ADHD or they are just a human being on the planet, feels as if their attention is being pulled in different directions. Sometimes without our awareness, sometimes with our awareness. What is this notion of recapturing attention?

3:04 Yeah, I think it's a really fundamental concept. Um, and we think that attention, you know, maybe on the surface of it, people just kind of think about, oh, it's kids trying to pay attention to school or, oh, it's trying to pay attention at work. But it's actually deeper than that. We kind of think that, uh, elements of attention are sort of involved in controlling all of our behaviors. Um, and when our attention is depleted, um, we don't have as much impulse control. We might behave more aggressively. Um, you know, we may not be able to achieve our goals. Um, and with a lot of things in the modern world, our attention is just being fatigued and we're depleted. And it's

3:52 really hard to recharge the battery or know what to do to recharge the battery. And I think that's kind of the entry point why I sort of got into interested in this. And one of my mentors, Steve Kaplan, would talk about this directed attention fatigue problem uh that a lot of us are facing. You know, our ancestors, you know, thousands of thousands of years ago, we're not bombarded with so much information like we are now. Now, the modern human has to sort of pick and choose what to pay attention to, and it's it's kind of overwhelming. And Steve uh Kaplan had this idea that humans kind of have two different kinds of attention. So uh one kind of attention is called directed attention. And that's kind of the attention that

4:37 I've been talking about uh just recently here. And that's the kind of attention where you as an individual person are deciding what to pay attention to. So presumably Andrew, you're deciding to pay attention to what I'm saying. uh even though there's many other things you could find that might be more inherently interesting than what I'm saying. And this is kind of a very, you know, unique human capability. There might be other species that can kind of decide what to pay attention to, but we're really good at it. Humans are really, really good at being able to like focus on this lecture or focus on reading this paper, focus on trying to uh finish this math problem, but we can't do it forever. Yeah. And I I think everybody kind of has had that sensation where uh at the end of a long workday, maybe three or four o'clock, you might

5:23 be just staring at the computer screen and you can't focus anymore. And we call that a directed attention fatigue state where you can't really control your attentional focus anymore. And I I I see this all the time when I'm lecturing at the University of Chicago and I and I think I'm a decent lecturer. First five minutes of class, all the students eyes are on me. They're engaged. Did you know I see they're nodding along with me and you know 45 minutes into my lecture I kind of see people nodding back like this. They're getting tired. It's just hard for people to direct their attention for long periods of time. So that's that's kind of the special attention, directed attention. We think there's this other kind of attention that we call involuntary attention and that's the kind of attention that's automatically captured by interesting stimulation in the environment. So

6:09 bright lights, loud noises, those things automatically capture our attention and we don't really have much control over it. And we think that kind of attention, this involuntary attention is less susceptible to fatigue or depletion. So you don't often hear people say, "Oh, I can't look at that beautiful waterfall anymore. It's just too interesting. I got to step away." Or, "Oh, I have to stop watching this movie. It's just too interesting. I'm too tired out." So that's a different kind of uh kind of attention and and we think what's happening um in modern times is that our directed attention is being fatigued. Um but uh maybe we can restore directed attention uh by going into environments

6:55 that can softly capture our involuntary attention. Do we know the basis of attentional fatigue? I mean, uh, I could imagine it's something in the noradinurgic, uh, dopamine, catakolamine world. Listeners to this podcast will recognize those terms, at least crudely. Uh, I could also imagine that it's literally a fatigue of the visual system andor the auditory system. You know, it's hard to maintain fixation, as we say, as visual neuroscientists to focus on a target. It's challenging. you know, um, if we allow our eyes to rest, it actually gets easier to look back at it and fixate on a target. So, what is the basis of the attentional fatigue for this focused attention or or what you call directed

7:40 attention? Yeah, it's a really great question. I'm not sure I have a great answer yet. U, maybe you'd have some ideas, Andrew. You know, one thing that that sort of to me puzzles me a little bit about the brain is that from my understanding, it's kind of like brain metabolism is 20% of overall metabolism. No matter what people are doing, except for really extreme exercise where brain metabolism goes down a little bit, but if you're asleep or if you're doing a hard calculus problem, I think the brain is still using 20% of metabolism. So, it's sort of this puzzle. Why do we get this mental fatigue state? I I'm It's got to have some kind of neurological component. At this point, I can't point to it. So, I'm going to talk about it more at this psychological level. It's the sensation that we have that we can't

8:27 focus anymore. If I was to talk about brain areas, I would say probably this ability to direct attention is most likely in frontal cortex. Um whereas this involuntary tension, sometimes we call it more bottom up attention or exogenous attention where it's activated by external stimulation. I would say that's probably more activated by things in the parietal cortex or even occipital cortex or auditory cortex depending on what that external stimulation is. I'm not going to lean everything on the visual system, but I've been listening to this book uh that unfortunately is only available as an audio book called Daily Rituals, which it's got two-minute chapters, and it describes the daily rituals of writers and artists and creatives. And um it's very interesting that across many of those chapters you

9:14 find the same thing which is that almost all of these people had a ritual of taking some stimulant typically caffeine sometimes more aggressive stimulants but caffeine and then something to restrict their uh visual world make it more tunnel vision. In fact, there were certain um painters I I forget the the particular painter that they described who literally built uh cardboard blinders onto his glasses when things weren't going so well. Um now, the reason I bring this up is not as a suggestion, although I suppose it could. Um I actually used to read papers. Maybe I need to go back to this. I put a like a baseball cap on, put a hoodie on, and you restrict your visual world. And it makes perfect sense if in fact involuntary attention which presumably comes from the periphery

9:59 right is inexhaustible right so you know I think what's interesting about the digital interface that we exist in now is that the whole world is brought right in front of us so presumably we evolved to move through space and direct our attention to particular locations and let the rest of the world fall away and then involuntary attention could grab us to alert us to people showing up or danger or the smell of something wafting by calling us for dinner. But now it's all placed right in our central visual field. So it makes sense that we would all be very challenged with um maintaining directed attention within that small tunnel vision. Yes. And I would say something else too. I guess if you felt like you had to create an isolation kind of chamber sort

10:46 of thing to focus your directed attention that's where we would say it's probably time to take a break that that's when you know we might recommend that you go for a walk in nature to recharge this kind of precious directed attention resource. So that might be a signal if if you're just having a really hard time focusing. Yeah, you can try to power through, but I think that might not be the most productive. That might be a signal to you to say, "Hey, maybe I got to go take a break." And the break better not be scrolling on social media. We're saying a really good break is actually a walk in nature or some kind of interaction with nature. I'd like to take a quick break and acknowledge our sponsor, Helix Sleep. Helix Sleep makes mattresses and pillows

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13:51 I want to talk about interaction with nature. I just wanted to it's not a push back on what you just said but maybe just a probe a little bit deeper. I think a lot of people struggle with getting into a focused state at the outset. Yeah. And I myself am familiar with uh the sitting down to do some work and it taking some time to kind of warm up and that agitation. I always think about it as literally um climbing over or through barbed wire. Sometimes it actually feels like that, right? Yes. And then at either side of the barbwire is a steep slope. On one side is distraction that can come from surfing the web or social media. And then on the other side is any sort of drama. Yes. And then of course our mind starts creating all these things that we think we need to do. And the idea is to get

14:37 through the barbed wire. And then on the other side of it is that focused state. For most people, I think what I described is not terribly different from that. Yeah, I'm making a lot of assumptions here, but I don't know many people that can just sit down to work that and just drop in like like, you know, like a trench. That's right. Um, can you do that? No. But I can do it better after a walk in nature. So, I think almost like the walk in nature is sort of like a preparatory kind of process. Um, just like, you know, think about like lifting weights or something like that. You wouldn't start off a workout and say, "Oh, let's put 250 on the bench and start going." You warm up. you got to wake up your your nervous system a little bit. And I think um

15:22 that's kind of a little bit what we think interacting with nature is kind of doing. I mean, it's not a passive process. We're not saying go and sit in a dark room for 30 minutes and then start to go to work. No, we're saying we want you to be interacting with nature. We want you to notice nature. We want your involuntary attention to be automatically captured by the stimulation in nature. And then after you've kind of been sufficiently recharged, then we think you're going to be able to go back to your desk and be able to direct attention and be able to focus. So, let's talk about some of the data around what walks in nature and interactions with other components of nature can do for our cognition and our level of focus. Um, I think intuitively people will appreciate, okay, a nice

16:07 walk in nature, not looking at one's phone. It's very pleasant. It's relaxing. And then you get back to your desk and you can really focus. What about the laboratory data that support this or out of laboratory data that support this? Maybe you could describe a few of the incredible studies that you've done because they are really incredible and they're very pioneering in the way that you've brought real laboratory technology into nature as well. So pick your favorite study about this and then I'll ask you about a few others as well. Well, I think the the kind of the seinal uh experiment that we did um was back in, you know, 2008. And at that time um when people did these sort of nature walk studies, they would ask people, "How do you feel after the walk?" And it was very subjective.

16:54 And I I'm not against uh subjective accounts. And people reported, "Yeah, I feel much more refreshed after the walk in nature." Um, but I always felt a little bit dissatisfied by that. I I wanted to see, well, does objective performance change? Just like we would probably be dissatisfied if I gave you a pill and I said, "This pill is going to uh get you stronger. You're going to be able to lift more weight." And if we just had people say, "Yeah, I feel like I can lift more weight." I don't think that'd be satisfying. We'd actually want to see, can people actually lift more weight? And so what we did is we designed a study um that was experimentally controlled that would have objective measures uh how did people perform cognitively before and after going on a walk in nature. So what we did is we brought

17:39 people into the laboratory uh and then we gave them some challenging working memory and attention tasks. So one of the task tasks was called the backwards digit span task where you would hear digits um out loud at a pace of about one digit per second and then the participant would need to repeat them back in backwards order. So if I said uh 567 the participant would have to repeat back 765 pretty easy task at three digits but we keep increasing the number of digits all the way till about nine digits. at about five digits you're ready to pull your hair out is a challenging task. So we gave participants uh this backwards digitis span task and then uh we gave them a map of a walk. Uh it could be the first studies

18:26 were through uh the Ann Arbor Arboritum which was a nature walk uh kind of by the psychology building at the University of Michigan or participants went for a walk uh on busy Washington uh street in downtown Ann Arbor. Uh the walks were both uh about 2.6 miles. So, it took people about 50 minutes to do the walk. Uh, we also took participants cell phones because we didn't want them texting or chitchatting on the walk. We wanted their attention to be fully focused on the environment. And we also did one other thing. We also gave them a GPS watch. Uh, why did we give them a GPS watch? Well, we did it for two reasons. One, we wanted to make sure they went on the walk. They didn't just go to Starbucks. And two, um, we wanted to see, did people get lost? Because if people got lost on the walk, maybe that

19:12 wouldn't be restorative. Okay, so people do the backwards digit span task. We send them on a walk in nature or we send them on a walk uh through an urban environment. They go on this 50-minute walk. They come back to the lab. We give them that same backwards digit span task again to see if there's any performance change or not, measure that. Then we have people repeat the whole procedure again. They come back to the lab a week later. So they walked in nature the first week, uh they walked in the urban environment the second week or vice versa. So it was all within subject very uh tight experimental control and what we found was pretty incredible that people's working memory capacity and their ability to direct attention improved by about 20% uh after the walk in nature versus the

19:57 walk uh in the urban environment. And people might be thinking well maybe it's just because uh the nature walk was just more pleasant. They just like the nature walk more. people did tend to like the nature walk more. Um, and we did measure improvements in mood. How much did mood improve on the walk? We didn't find very strong correlation between improvements in mood and improvements in the working memory and directed attention performance, suggesting that people weren't just getting better because they were getting into good moods. But the even stronger demonstration that this wasn't mood driven is that we had people walk at different times of the year. So, some of our participants walked in June when it was like 80 degrees Fahrenheit. People said, "Mark, I can't believe you're paying me to go for a walk in nature." Really healthy mood benefits,

20:45 really healthy working memory and attention benefits. We also had participants walk in January, 25 degrees Fahrenheit. People said, "Mark, I was freezing my butt off out there. I did not enjoy that walk." But incredibly, the people that walked in January when it was freezing cold and they didn't enjoy the walk obtained the same working memory and attention benefits as the people that walked in June. So you didn't even have to like the nature interaction to get this directed attention benefit. So that I thought was pretty interesting and counterintuitive that this isn't just about liking or pleasantness. There's something deep about processing auditory, visual, maybe even tactile stimulation of nature that somehow is good for our brains and restores our ability to direct attention.

21:31 Super interesting findings and it leads me back to this um uh finite resource of directed attention whatever the underlying networks and chemicals happen to be. Could we speculate what might be occurring in the nature walks that is um enhancing or allowing restoration of directed attention? And I guess the neurobiologist in me wants to say, okay, I'm walking in nature. That probably means some greenery, um some dirt, uh maybe some water. Um, and I could imagine one hypothesis that it's the uh kind of irregularity of nature environments, right? I mean, maybe trees are spaced out, you know, in perfect

22:18 spacing like on Palm Drive at Stanford. It's like it looks like a it it speaks to the engineering department that there's it's set at such even intervals, right? But, um, typically when you're in the forest um or nature, there there's also things to break up that regularity. Um whereas indoor environments and city environments tend to have a lot of right angles, buildings can be different sizes, but city blocks are pretty fixed for a given neighborhood in terms of their size. So that's just one hypothesis. I'm coming up with this off the top of my head. Do we have any data or do you um have any preferential speculation as to what it is about nature in terms of its physical structure? And as a correlary to that, is it that nature is relaxing people and

23:04 therefore they're not having to use their directed attention and therefore directed attention capability comes back or is set at a higher level? Um I realize this is two questions kind of uh braided together, but that's what I'm curious about. Yeah. And I think um I think both elements are played. So maybe I'll start first with kind of the the resting directed attention element. So, let's let's pretend we're on these walks in nature or the walk on the urban environment. And I'll start with the walk on the urban environment. The walk in the urban environment um required people to cross a lot of streets. So, you had to be vigilant. So, you still had to use directed attention. Also had a lot of car traffic. So, you're hearing the noise of cars whizzing by at probably, you know, 40 45 miles per

23:50 hour. There's also advertising. you're going by shops and billboards that that kind of require some directed attention. So, you can't really just mind wander and and let your mind kind of go in those environments. You still have to be vigilant. You still have to use directed attention. The walk through the Ann Arbor Arboritum, you didn't have a lot of those distractions. So, I think you only had to cross one or two streets and then you're kind of uh getting towards the arboritum. You don't have to cross any more streets. Um there's no advertising there. And then and and this is the thing I want to talk about too. This idea of soft fascination. There's all the colors, fractalness, curved edges of nature that we think um sort of captures our

24:38 involuntary attention in what we say is softly fascinating ways. And we think that in combination with not placing a lot of demand on directed attention is why nature is able to restore directed attention. So what do I mean by softly fascinating stimulation? So let's pretend we're looking at a waterfall and the waterfall is really beautiful. You can hear the rush of the water going down. You can see all the like the bubbles and maybe some of the froth of the water going down. It captures our attention, but we can still kind of mind wander and think about other things at the same time. So, it doesn't really harshly capture all of our attention and resources. If we're in Time Square, also super interesting. Lots of interesting

25:24 stimulation to look at, but it kind of captures all of our attention resources in an in an all-consuming way that doesn't allow for any reflection or mind wandering or anything like that. So, while Time Square does capture our involuntary attention, we say it does. So, in a very harshly fascinating way, whereas the waterfall captures our uh involuntary attention in a softly fascinating way. And we think that's the way that's going to be restful eventually of directed attention. So, we think two elements uh created why the nature walk was restorative. one, it didn't place as many demands on directed attention, and two, it had this softly fascinating stimulation that activated this involuntary attention, but not in an all-consuming way. So, we think those

26:10 two things are critical. The other point that you bring up about, okay, well, what what causes soft fascination to be captured or or why does something capture involuntary attention in a softly fascinating way? And that gets really interesting where we think it could be elements of the structure of nature. So, it's interesting, Andrew, that we can get these effects of um nature improving cognitive performance. People just looking at pictures of nature versus looking at pictures of urban uh scenes, listening to nature sounds versus listening to urban sounds, watching nature videos versus watching urban videos. So, there you don't have to worry about getting hit by a car. There's something about the visual aesthetic

26:56 of nature that we think is producing some of those benefits that somehow our brain maybe processes that fractal stimulation in more efficient or easier ways than kind of what you were talking about the 90° angled built environment that we've uh constructed. I have to ask if you are exposing people to nature images versus um urban environment images in the laboratory and seeing some of these same effects, are you presenting that on a typical, you know, small screen right in front of somebody or is it in panorama? I'm headed in a particular direction with this question. Um because I have a pet hypothesis as to what nature could be doing um to not deplete directed attention. Uh, but before I ask you

27:42 about that, I'm just curious what the experimental setup is. I'm also asking because I'm a little concerned that people are going to hear, "Oh, great. I can just look at a picture of a forest. I don't have to get outside." And as you mentioned, there are so many things in a in an actual nature environment that, uh, provide a rich experience of soundsscape, etc. But, uh, what's the format? Yeah, so it's, uh, basically the same format as the walk, uh, the walking study that I described. So people come into the lab, we give them uh the backwards digit span task, but then we take them into a room in the lab where they just have a computer screen that's flipping through uh nature scenes or urban scenes. They look at the scene for a couple seconds. We also have them rate the scene on a scale of 1 to three for

28:27 how much they like it just to make sure that they're awake and they're engaged with the environment. Uh that whole procedure takes about 10 minutes. uh they come out of the laboratory room that had the pictures and then they take the backwards digit span task again um to see if there are changes in uh performance and then we'd have them come back to the lab a week later repeat the whole procedure again. If they saw the nature pictures the first week, they see the urban pictures the second week or vice versa and they're even just seeing the pictures of nature we see um improvements in working memory and directed attention. However, I would caution that the effects are not as large as they are for the actual walk. Um, so it's harder uh or I would say I guess the the

29:14 intervention is not as strong as actually walking in nature, right? Just seeing 10 minutes of nature pictures, it's incredible that it works. You can get some of these benefits, but the benefits are not as strong as they are for the real thing. And the same procedure happens when we test um sounds of nature versus urban sounds. We test people uh with the backwards digispan task. Then we put headphones on them, play a series of nature sounds or play a series of urban sounds. Then they do the backwards digispan task again. Um and we find that when people listen to nature sounds, they also show improvements on um on working memory performance and directed attention. We don't do anything uh special in terms of having it being a panoramic view. It's basically just looking at a slideshow of nature

30:01 pictures or urban pictures on a computer screen. As I'm hearing this, I'm starting to wonder whether we have brain areas andor circuits that are devoted to nature. Uh which you know first pass seems like kind of a crazy idea because visual perceptions and auditory perceptions are built up from their sort of elementary units which is just nerd speak for you know your eye and low-level visual system cares about uh circles and angles and then your higher level cortex puts it into the recognition of a person or a building etc is literally built up from from elementary units you know in the sound domain it's built up from different frequencies, etc. But, you know, there's something about

30:47 this problem. Uh, here here's what's on my mind here. If I walk through a neighborhood, an urban neighborhood where it's a bunch of warehouses, um, with some cyclone fence and some signs and it's a weekend, maybe it's a Sunday and they're all closed. There aren't trucks coming in and out and not not a whole lot's happening. Yep. This is It reminds me of uh like West Oakland near the shipyard on a Sunday. Yep. Right. Not a place I recommend people go unless you really like kind of bland urban environments on a Sunday cuz not much is happening. It's a shipyard Sunday. It's closed versus a trail in Yusede. I used to work up in Yusede in the summers, but it's not one of the most magnificent trails. Uh meaning it's not Yusede Falls,

31:34 Halfdme or Clouds Rest. My favorite trail. It's a kind of barren environment, but there might be a meadow and there might be a mountain. You would never say, you know, this trail up in Towalami that I'm on right now is it's kind of boring. It's not as interesting as the peak of Clouds Rest. And arguably, it's not. I mean, when you get to the top of Cloud's Rest, it's like, whoa. Yeah. Like it I mean, it's a spiritual experience. Okay. But when we are in nature, we don't tend to think, oh, this is boring. There's nothing here. Even if it's fairly sparse visually. So So as we dissect this, it can't just be density of visual stuff. No, there must be something additional. Even and we could say, well, maybe it's the greenery.

32:19 But you know, I was out in the Utah desert not that long ago. And it wasn't arches or you know, the beautiful uh you know, landscapes that definitely exist out there. It was just kind of like horizon sky, some sand, maybe a cactus or two, some rocks. But it's beautiful. Yeah. Right. And you would never say, "Oh, this is boring because it doesn't have arches." When you get to arches, you're like, "It's that much better." Right. You get the point here. So, it can't be density of visual objects, right? Um, and it's pretty quiet out there in the desert, except at night when it's really quite noisy in a desert actually with animals and and stuff, uh, if you're lucky. So, what's what's the deal? Part of it could be evolution to some extent. I mean, our brains evolved in nature, right? So it is it possible that our neural machinery is just more tuned

33:07 to that kind of stimulation? I mean there's no natural right angles in nature. We created right angles. I mean that's pretty speculative, right? And I'd want to dig in a little more about that. But I I can't ignore it that there's just something maybe fundamental with how our brains evolved um and we evolved in nature that there's just something maybe about we just maybe more fluently process natural stimulation and we and maybe we like that. But we started to have some ideas, you know, soft fascination. I I love it um as a concept, but it still is a little bit squishy. I kind of wanted to get some kind of quantitative parameters around it. So, one idea that we were thinking about was that

33:53 maybe nature scenes are actually more compressible than urban scenes. Now, what do I mean by that? So, what I mean by that is that maybe they just there's because there's repeated patterns in nature, I don't need to store all of the information. I can kind of smush it down into fewer bits. Um, and that might be easier for my brain to process. Whereas in a lot of urban scenes, it's not very fractal and maybe I have to store all of that information. So we actually, this is one of my students, Nwan, we actually did, we ran a JPEG compression algorithm on thousands of nature and urban scenes. And it turns out nature scenes get compressed down into fewer bits. Um, so we should, no pun intended, unpack a little bit of what you just

34:39 said because I think, um, for people that are not familiar with thinking about neural processing, and JPEGs versus TIFF files. Uh if if I may, I'm just going to give my crude rendition of this because I I was very interested in this and and did some work related to this years ago. But just to keep it brief, um people are probably familiar with the idea that some electronic files are larger than others. So if you have a picture that you take on a camera or your phone and you want to email it to somebody, nowadays you would just text it, but you might want to email it to somebody. You can send them the TIFF version or the Photoshop version and it's going to be a very big image or a big movie for that matter, right? There's another way to send it which is at a lower file resolution,

35:24 right? But um therefore takes up less memory, doesn't come through as this massive file that you need to go to a second party site to download or something. And that's a JPEG, right? The whole basis of JPEG is to take the average of pixels near one another and compress them. kind of take a best guess as to what a black pixel is probably next to another black pixel or probably a gray pixel but probably not a white pixel. It could, right? But it what it does it takes a local averaging. Yes. And then it compresses it into a JPEG and you send it to the other side. Yep. But on the other side you can also unpack that image to its original highresolution value. The brain does a similar thing. And the best example that I have from the brain is the alactory system where in the alactory system you're breathing in tons of volatile chemicals. Meaning

36:12 volatile makes it sound like they're about to throw a tantrum, but um they're they're moving through the air. You inhale them and they're activating millions probably of different odorant receptors, but your brain compresses those down into coffee. This is coffee. And then you unpack it as coffee. Now, if you're a coffee connoisseur or in the case of wine or a food connoisseur, you can get into the subtle nuance and say, "Oh, you know, there's a li little bit more of this and a little bit more of that, but you're not thinking about the individual chemical molecules." You'd say, "Oh, it's a little bit of a cherry flavor or this chocolate has a little bit of a citrus." You know, this is the sorts of thing. So, that's essentially what the brain does with visual images as well. Yes. Okay. So that's my um very crude and um certainly not complete um description of

36:58 how bits of information are compressed as they go into the brain and then unpack into what you call a perception. That's right. Or an experience. And the same thing is true of a TIFF or Photoshop file compressed to a JPEG. Um and then you can literally uncompress that file uh if you have the cap the sort of computational capability. So, one thing I just want to add to it, the the kind of compression that we were doing with the JPEG compression was was lossy, meaning that the information was thrown away. You couldn't recover it, but that didn't really matter. So, if you showed people the image at its high resolution versus the image at its compressed or lower resolution, the human eye can't really tell the difference. And I think um but for the urban images, you couldn't get away with

37:43 that trick. you needed to to keep all of the original pixel values. So that's kind of that's what computers and our iPhones are actually doing there. Um and the reason why we think they can get away with that is because nature has a lot of this repeated structure like you were talking about before about predicting the pixel's value and you can use that you can capitalize that that means there's a lot of redundancy so you don't need all of that information. Natural images also tend to have, maybe this is gonna get a little bit technical too, a lot of high frequency spatial content. There a lot of little changes or little contrast changes that we don't really need. Whereas in the urban environment, there's more of these big contrast changes that we do need.

38:28 So we think maybe the brain is like you're saying there's all this evidence that the brain is basically doing that and in nature because you can sm you know you're walking through the nature you can kind of throw away a lot of the information and so we think that actually might be why it's sort of more softly fascinating and easier to process versus the urban environment. There's another element here too which we haven't got it completely yet but which I'm very interested in. So that that's looking at sort of like complexity of the images at the very very low level. But you could also think about semantics like the language that we use to describe a scene. And when I see a nature scene you know I don't have a huge language repertoire. I can say

39:16 lake, tree, river, shrub, sand, desert. But when I'm in the urban environment, I can say Volkswagen Beetle, you know, BMW, M3, uh, Gothic architecture. Like my vocabulary is so much more complex for an urban scene. So, so one thing that we're also thinking about is like maybe nature might also be more semantically simple like from a linguistic level that I can just label it really easily and then it allows my brain to just not have to store as much information. Whereas in the urban environment maybe I'm forced to sort of label all these objects and it just takes up more room in our brain. So, we also do these studies where we show

40:01 people a bunch of nature scenes and urban scenes and then test their memory for the scenes. And it turns out that people's memory for the nature scenes is worse than the urban scene. So, people remember exactly it fits. It fits. And you might think, oh, well, you want to remember stuff, but actually, you know, in some sense, it's it's measuring how how just difficult it is to process. and and we're if it's so easy to process nature, you're just not going to remember it. And that in this case is a good thing. So we think that's also part of it that it's that that's also saying to us that yeah, it's just it's just easier to process this natural stimulation versus this urban stimulation where you just have to attend to more stuff. It's more sticky. Do you have any data as to whether or not people track time better or worse

40:48 when they are in natural versus urban environments? So, I don't have direct evidence to this, but I have a few other little pieces of evidence that I think will kind of get us there. So, we've done some studies where we send people uh this one was actually uh sending people to a nature arboritum, an indoor nature arboritum, the Garfield Conservatory, a really beautiful conservatory in Chicago versus the Chicago Water Tower Mall, a very fancy indoor mall in Chicago. And uh we actually gave uh participants here uh cell phones that we had in the lab that would ping them uh and ask them questions while they were going on the walk in the conservatory, the walk in the mall. And we asked them, you know, what are you thinking about? And it turns out when people were walking in uh

41:35 nature, they actually think more about the past uh than walking um in the mall. So that was kind of interesting. Mhm. Um, this is also kind of interesting. People also said that they felt more impulsive in the mall than in the conservatory, which makes sense that, you know, mall designers want people to be buying things. Um, but this idea about thinking about the past to me suggested a little bit that time might be going a bit slower. Other people have found in cities that the larger the city is, people like walk faster, like the pace of everything is a little bit faster. So my hunch is that based on those two findings that I think time does probably slow down in nature, but I don't have direct evidence for that. I I

42:21 think that's something that'd be really super interesting to study. But that would be my hypothesis that in nature time does slow down a bit. If you had to wager a guess, would you assume that going into an art gallery is more similar to taking a walk in nature or an urban environment? I mean, it's so rich with information. You have options. You have to decline certain things, certain rooms, certain paintings, certain sculptures. There's a lot of decision making. And yet most people find galleries, big galleries to be extremely calming. Maybe it's also because everyone's quite quiet in them. I would say the the gallery is would have a similar effect to nature would be my guess because, you know, Kaplan's attention restoration theory

43:07 really is not specific to nature. It basically just says you got to find an environment that doesn't place a lot of demands on directed attention while simultaneously having softly fascinating stimulation. And an art gallery might meet those two criteria. If you don't have to be tested on the artwork and you can just kind of go there and you don't have an agenda, I think there's going to be a lot of very softly fascinating stimulation in an art gallery. So, my hunch would be that yeah, walking through an art gallery might have a similar kind of effect. Um, I would, this is going to be a little bit of a jump. There, there are some studies that we did where we were looking at the relationship between park visits and crime and going to a museum

43:55 versus crime. Um, so these were there's been a lot of actually interesting studies suggesting that interacting with nature can make people less aggressive and we think it has to do with attention. So we uh, you know, we had this incredible data set um, this cell phone trace data set where from a 100,000 people in Chicago, we knew where they lived um, and we knew where they went for an entire month. So what we did is we quantified how many times did people leave their neighborhood and go and visit a park versus leaving their neighborhood and going to a museum or something like that. And we wanted to correlate that with crime. And sure enough, we found

44:43 that neighborhoods where people leave their neighborhood and go and visit a park, there's actually that predicted less crime in those neighborhoods. But the museum visits didn't predict that. And this was controlled for I don't know like uh socioeconomic background. Yeah. I mean more or less I mean again it's a correlational study so I can't claim causality but we also controlled for age, education, income, all those demographics. Um so there it seemed like there was something special about the park visit versus the museum visit on at least aggression. Um but I do believe that um going through a museum might have a similar effect to nature. I'm not sure it'll be as strong, but I think it has the the museum maybe has a lot of the same elements that uh that a nature walk

45:30 might have. I mean, I think I'm just obsessively starting to drop into the trench of, you know, what sorts of things are attention depleting and what sorts of things are attentionally restorative. Uh because I personally believe that our ability to attend is like the hallmark of building a great life. Yes. And I've so much so that you know on on hikes and walks I will listen to audiobooks and podcasts. Yeah. Um but there are times when for instance I will exercise with silence. Yep. And then I'll use music as something to like push me through some particularly hard moments in the exercise, but then I'll turn it off and bring it back. I I don't just kind of like head out the whole time blasting music. Sometimes I'll do that but I'm I'm starting to become kind of a

46:18 experimentalist with this idea of you know attention as this resource that we deplete each day sleep it's restored mostly go back again I mean you know looming in the backdrop of this conversation is conversation about social media but but before we go there if you were at this point to give a kind of a best recommendation in terms of how to reset one's attentional abilities uh what are the basic requirements. So, I think there's there's a lot there, too. Um, I think you have to be really mindful about directed attention fatigue. So, if you're trying to study or uh you're at work and you're having a really hard time concentrating, I would recommend not just trying to

47:04 power through. If if you have the ability uh and the time to take a break, I recommend that you stop and you take a break. And what kind of break do I recommend you do? I recommend that you go and try to find some nature and walk in nature. What if you're you're having a hard time getting into a focused state at all. It's not that you fatigued it that day. you you know so many people that I hear from uh who listen to the podcast and elsewhere will say you know they they get up they did their best to get their sleep they get their morning sunlight they hydrate they drink their caffeine they sit down to their computer and they just can't focus and then they start thinking like do they have brain fog do they have do they need a neutropic you know that all these questions start to arise

47:50 what what are I think in some sense even though you might be very well slept and very wellfed, you could still be in a directed attention fatigue state. So, I think yeah, if you can't concentrate right in the beginning of the morning, then you should go for a walk, right? That should be the first thing you should do. Or if you don't have access to nature, maybe listen to some nature sounds or or watch a nature video or something like that. We find that all those things can be beneficial. Even looking out the window to nature can be beneficial. Looking at a picture, you've got a picture of nature here, looking at a picture of nature can be beneficial. So, I would say anytime you're having trouble concentrating, it doesn't have to it doesn't matter if it's at the beginning of the day or the end of the day or the middle of the day, we I would recommend that you take some kind of break with

48:35 nature. And it could be simulated nature like uh listening to nature sounds, watching a nature video, looking at nature pictures or even better is if you can actually get out and uh interact with nature because Steve Kaplan used to also talk about these other elements that might be important for a restorative environment. One was that the environment had to have extent meaning that it had to have enough interesting things to look at. Now it doesn't mean that it has to be Yoseite Valley which has incredible spatial extent. I mean it's huge. It's enormous but you know like near my office um at the University of Chicago we have this uh Japanese garden the garden of the Phoenix. It might be only like a 100

49:23 square meters. It's pretty small but man it's still got a lot of extent. You know it's got a a walking path. It's got a little waterfall. you can see Lake Michigan. Um, so that's one element. Another thing uh about the the nature is that you want it to be compatible with your goals. So, so what do I mean by that? If you've got a big exam and you haven't studied, I'm not sure going for the walk in nature is going to work. You better use that time to to study. But if you can't concentrate, you know, trying to power through, I don't think is going to be compatible with your goals. I think going in for the nature walk is compatible with your goals. So that's another thing that's going to be really

50:08 important. And the other concept uh that Steve used to talk about being important is this is that the environment needs to give you the sense of being away that you're kind of removed um from your current environment almost like a change of mindset. Um, and again, that doesn't mean you have to go really, really far away, but you might want to go to a location that's not at your desk. So, maybe don't sit at your desk and look at the nature pictures. Maybe you want to go somewhere else and look at the nature pictures. And this kind of distance, I think, could be helpful. I don't know if Kale Newport talks about this in his deep work, but, you know, I've heard people talking about in an office, you might want to have like a separate area of your office for deep work. And I think this kind of sense of being away is related to that. you kind of want to get out of your current state

50:55 and go into this other environment that might be able to replenish those resources. So, I'm hearing that there are two sides of the coin. One is to designate an area for work that's truly for deep work. Yes, I followed Cal's recommendation and now I have an area in my basement, believe it or not, and there has never been a phone in that basement. There's no phones allowed in that basement. That's that's not a rule. It's not a protocol. It's a policy, right? And I remember he talked about in his he has this library office that he goes to and I'm I very much agree with that. Yeah. Now I do get internet access down there a little bit if I need to look for papers, but um I've been turning off Wi-Fi on my computer when I go down there to work. And I get more done in 3 hours down there than I would in 3 weeks above ground. I

51:42 swear it's it's a huge effect. Um, the other side of the coin is this business of getting out into a different environment and it sounds like these walks or these ventures into nature don't take terribly long. H how long does one need to do this in order to get the enhancement in focus and working memory? Like what do the data say? Yeah, I mean when we did the our walking study was 50 minutes but I've seen other studies with as little as 20 minutes you can get the effect cognitive enhancement for cognitive enhancement. Um, and there's actually been some interesting studies with kids with ADHD, and they find attention benefits uh for these kids with ADHD after just a 20-minute walk in nature that actually was similar um to like a dose of rolin. So, that was pretty incredible. So, it doesn't have

52:27 to be super long. Uh, and when we were doing the the slideshow of nature pictures, that was only for about 10 minutes. So, it doesn't have to be a really really long immersion. There have been other studies that have suggested like overall uh you might want to get about 2 hours a week in nature. I'd like to take a quick break and acknowledge our sponsor AG1. AG1 is a vitamin mineral probiotic drink that also includes prebiotics and adaptogens. As somebody who's been involved in research science for almost three decades and in health and fitness for equally as long, I'm constantly looking for the best tools to improve my mental health, physical health, and performance. I discovered AG1 back in 2012, long before I ever had a podcast, and I've been taking it everyday since.

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55:32 sticks to it, so it's really easy to clean, and it's even dishwasher safe. I love it, and I basically use it constantly. Our place now has a full line of Titanium Pro cookware that uses its first-s titanium non-stick technology. So, if you're looking for non-toxic, long-lasting pots and pans, go to fromourplace.com/huberman and use the code hubman at checkout. With a 100-day risk-free trial, free shipping, and free returns, you can experience this terrific cookware with zero risk. You know, I've been long obsessed with this um difference between what happens in our brain stem, you know, the areas involved, as you know, um with levels of arousal and stress versus calm. um when we look at a fixation point versus a

56:17 horizon or when we go into panoramic vision and there are now ample data to support the idea that when we fixate on a small box like a phone or a computer or we you know we're fixated on something we're reading or paying attention to it that our level of autonomic arousal creeps up doesn't creep up indefinitely but this makes sense right visual attention matches the cognitive attention you need arousal aka alertness to get cognitive attention but that when we go into panoram amic vision which is you know for the aicionados you can look at magnosellar vision what you're essentially doing is you're taking bigger pixels of the of the visual environment yes and when we look at a horizon y we naturally go into panoramic vision unless we're looking at our phone taking a picture of that horizon so take note it's interesting to me to think about

57:03 visual environments such as nature that that have us taking larger bins pixels if we're talking about visual space but that we're also perhaps, this is a question I'm obsessed with, perhaps taking larger time bins. What do you think about a kind of a general idea that what we need to do in order to be focused? Yeah. Is to allow our mind to go into these kind of like timed drift states. Yeah. And I kind of think, you know, you're talking about it from a a visual perspective, but I think it's also from a cognitive mental perspective. So I think also too being in nature kind of widens your cognitive you know landscape you and that's why I think people sometimes you know you hear all these anecdotes where people are struggling to

57:50 solve a problem they can't figure it out they go for a walk in nature and then boom they they solve the problem because the brain is still churning on that right but maybe being out in nature sort of inspires this widening of attentional space internally We had a guest on this podcast, Michael Platt from the University of Pennsylvania. He's a neuroscientist, and he told us about this experiment. It's pretty wild. I This still blows me away. You're probably familiar with it, but I wasn't, which is that if you have sub human subjects in a lab, do a connect the dots task where the dots are placed very close together. Yeah. Versus a connect the dots task where they're uh the dots are placed much further apart. And then you give them a creativity task. the people who do the task and it's well controlled for folks. Um connecting dots that are further

58:37 apart in physical space show significantly elevated levels of of of creative insight to solving problems. And so there's something about visual space and time and our ability to link um things in cognitive space and time. This is why uh when you said earlier that when you're out in nature there there aren't as many words to describe things. What that means to me if I think about the results that Platt was talking about is that perhaps it isn't just that that um there's a der of language but perhaps then your brain starts to drop into other like modes of cognition. I don't want to sound too nerdy just to sound nerdy here but that you know there are all sorts of things in your brain that have that are that are that can't have words assigned to them.

59:22 Like for instance, your childhood, you could give the whole story, but it still wouldn't capture it, right? But there was your trauma, there was your winds, there were your um falling in love, you know, we have these words, but they don't capture the experience. They don't capture like the the visceral experience, the smells, the taste. And so um I love the idea that in nature things are sparse enough yet rich enough that maybe these networks get get triggered, right? And I think, you know, this is kind of another, if we want to get into the neuroscience a little bit, we have some of these ideas that um for what a brain looks like when it's kind of at rest. And um when we talk about fractalness,

1:00:09 you know, most of us think about like a spatial fractal. So if there's a snowflake, it's got a characteristic shape. If you put that snowflake under a microscope and zoom in, it still kind of has that same shape. If you zoom in some more, it's still got that same shape. Um, so it doesn't matter at what scale you look at the snowflake, it's got the same shape. So that's called that the snowflake is sort of scale-free spatially, or another way to say it is that it's fractal. It's got this repeated patterning at these different spatial scales, and nature is filled with fractals. Could you tell us more about some of those? I I recall hearing about fractals

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