How Your Thoughts Are Built & How You Can Shape Them | Dr. Jennifer Groh

Jennifer Groh: What goes on in our brains when we think might be that we're running simulations related to the thought, using that sensory-motor infrastructure of the brain.

Andrew Huberman: Could you elaborate?

Jennifer Groh: So the theory is that maybe when you think about a cat, for example, or you think about the concept of a cat, the mental instantiation of that, or the brain mechanism instantiation of having that thought, is to run a little simulation in the visual cortex that kind of includes what a cat looks like. A simulation in the auditory cortex, what does a cat sound like? And as I'm telling you this, I've used the word cat. What color cat are you thinking?

Andrew Huberman: I'm thinking of a gray cat, but I keep smelling kitty litter.

Jennifer Groh: Okay.

Andrew Huberman: Because my sister had cats, and it drove me... The smell of kitty litter is just so aversive to me.

Jennifer Groh: Right. And so, you had no hesitation in telling me the color and adding an additional sensory quality. It provides an explanation for why you might be driving on the freeway and having to merge into difficult traffic, and telling your passenger, "Okay, be quiet, I have to pay attention now." Like, why would speech impair you from visual-motor if it wasn't all part of a kind of cognitive system that's in operation, and maybe you need to shift some resources away from processing the conversation and towards actually dealing with the here-and-now sensory-motor task?

Andrew Huberman: Hmm. Mm-hmm.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Welcome to the Huberman Lab podcast, where we discuss science and science-based tools for everyday life.

Andrew Huberman: I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. My guest today is Dr. Jennifer Groh. Dr. Jennifer Groh is a professor of psychology and neuroscience at Duke University. Her laboratory studies how our brain represents the world around us.

Andrew Huberman: In particular, how our different senses are merged in the brain so that we can focus and learn more effectively, including how our eye movements fundamentally shape not just what we pay attention to, but how they dynamically control what our brain is capable of. What she shares is fundamental to understanding how your brain works and also how best to focus on and learn different types of information. Not just information that you might read on a page, although including that, but also what you hear, what you remember, and the very thoughts you have about your life experiences.

Andrew Huberman: We also discuss thinking itself. In fact, we discuss what thoughts really are. And there, Dr. Groh shares with us what is perhaps the clearest and most useful definition of what thoughts are and how you can control them. As someone who has been in the field of neuroscience for nearly three decades, I must say that her explanation of what thinking is at the neural level, at the psychological level, and at the experiential level is the most compelling and useful one I've ever come across.

Andrew Huberman: Today, Dr. Groh explains how to use your experiences, the information you encounter, and knowledge of how thoughts are built up in the brain to become a better thinker and indeed smarter. I'm certain that the information you'll learn from Dr. Groh today is not like any other discussion you've heard about the brain or psychology. I'm also certain that it will be extremely useful for anyone wishing to better understand how the brain works, how their thoughts and emotions arise, and anyone who wants to get better at learning, thinking more deeply, or simply experiencing life with more richness.

Andrew Huberman: 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 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. Jennifer Groh.

Andrew Huberman: Dr. Jennifer Groh, welcome.

Jennifer Groh: Thank you. It's great to be here.

Andrew Huberman: We've never had a proper conversation on this podcast about sensory integration. We've talked about vision, talked a little bit about hearing, a little bit about touch, smell, and taste, but we've never talked about how the senses come together, and that's critical to everyday life, critical to perception.

Jennifer Groh: Absolutely.

Andrew Huberman: I know you've focused perhaps mainly on the auditory system, but you really are an auditory-visual integration person. I know this because I've followed your work for a number of years. So where in the brain do our eyes and our ears first come together to impact our perception of life? Like, the tea kettle is whistling, or we hear a knock on the door. We know where the door is, and we know where the tea kettle ought to be, but where do these things first collide?

Jennifer Groh: The story that is triggered by that question is a little bit long, so maybe I can start at the beginning of when I first got interested in this question.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And so I was a college student. I was interested in neuroscience, but we didn't have a neuroscience major, so a couple of us talked a professor into offering a seminar in neuroethology, and kind of what he thought were sort of the coolest findings in neuroscience. And in that class, I learned about a study showing that... And I'm going to begin with the neuroscience nerdy lingo, and then we'll unpack it.

Andrew Huberman: Mm-hmm.

Jennifer Groh: That there's a brain structure called the superior colliculus that's responsive to both visual and auditory stimuli, and that the responses to auditory stimuli depended on where the eyes were looking. If you moved the eyes, the neurons' receptive field, the region in space where they were responsive to, would shift as the eyes moved. And that blew my mind. I could not get that out of my head, and it kind of set me on the track that I've been on ever since then.

Andrew Huberman: Mm-hmm.

Jennifer Groh: One of the things that was really interesting to me about it is that figuring out where a sound is with respect to where the eyes are looking is something that would be easy for us to do with a pencil and paper. You know, it's very simple math. If you know that the sound is located, say, 10 degrees to the right, and your eyes are looking 10 degrees to the left, then that tells you that the sound is 20 degrees to the right of where your eyes are. Really not that hard to do.

Jennifer Groh: But from what I knew at that point about how the brain represents this kind of spatial information, it seemed a big puzzle for how the brain might actually create these kinds of moving representations of where the sound is located.

Andrew Huberman: Yeah, because what you're talking about are dynamic maps.

Jennifer Groh: Yeah.

Andrew Huberman: Like, I think most people probably appreciate that we have a map of our body's surface, a so-called homunculus.

Jennifer Groh: Right.

Jennifer Groh: Yep.

Andrew Huberman: And so if one were to stimulate a given region of the brain, you would have the illusion of being touched at that location on the body. People perhaps have seen that the more sensitive an area of the body, like the fingertips or lips or face or feet, the larger the representation in the brain. But what you're talking about is shifting maps depending on where the eyes move, and the eyes move quite a lot.

Jennifer Groh: They move quite a lot, exactly, and mostly we're not aware of this.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Right? But if you think about it, every time your eyes move, the visual scene is shifting massively on the retina.

Andrew Huberman: Mm-hmm.

Jennifer Groh: But we don't even notice this.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And this is an indication that the brain is doing a ton of computation under the hood to give us that perceptual experience.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Because if we were just representing reality, the reality would be these massively shifting, smeared visual scenes.

Andrew Huberman: One thing that's so intriguing to me about the auditory system and the visual system, is the extent to which they can contract and dilate so fast.

Jennifer Groh: Mm-hmm.

Andrew Huberman: So for instance, if I'm walking to get on public transportation of some sort, like a light rail or a subway, there's sound going by me, it may or may not be relevant, but at some point, I sit down. Chances are, I open up a book or a computer, or these days, people go into their phone. And we say "into the phone" because there's a lot of sensory information there, but our visual world and our auditory world just go into a small box.

Jennifer Groh: Right.

Andrew Huberman: And we expect whatever we're looking at to relate to the sounds that we're hearing in that small box.

Jennifer Groh: Right.

Andrew Huberman: But if somebody says, "Excuse me, do you have a ticket?" You know to look up.

Jennifer Groh: Right.

Andrew Huberman: We take this for granted.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Like most people might think, "Of course you look up." Like, the sound is coming from over there. It's now a person. But all of a sudden, we can remap our visual-auditory world and all the context in milliseconds.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: So is that all happening, and we've been talking about the superior colliculus in this structure, the superior colliculus, below our neocortex, meaning is it below our kind of conscious awareness?

Jennifer Groh: You know, gosh, I wish we knew where conscious awareness was.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I think that's an open question.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And the superior colliculus is important in this story because that's where the research began. It's not that that's where the binding of visual and auditory space is necessarily fully contained there and only there.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I think it's a much bigger problem, and I think what you're describing is kind of another version of this kind of capturing of or integrating or connecting the information from one sensory system to another. That kind of shifting your resources around is something that happens in a few different contexts, like what you're describing.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And I think one of the things that's really interesting about the phone, or really any screen where you're watching a video, is that the sound was never coming directly from the screen where you're looking at the visual image.

Andrew Huberman: Mm-hmm.

Jennifer Groh: You know, it's coming from somewhere else. Maybe you've got earbuds in, and it's coming from the earbuds. Maybe the earbud signal is simulating what the location should be if it was really coming from the screen, but it's a simulation. It's not actually reality.

Andrew Huberman: Oh, yeah. That's so interesting. So yeah, let's unpack this a bit. So we merge what we see with what we hear if it makes sense to merge them.

Jennifer Groh: Yep.

Jennifer Groh: Right.

Andrew Huberman: Like, lips are moving.

Jennifer Groh: Lips are moving.

Andrew Huberman: And that's in our hand, about a foot in front of us.

Jennifer Groh: Mm-hmm.

Andrew Huberman: But the sounds are coming in elsewhere.

Jennifer Groh: Right.

Andrew Huberman: This is very different than, say, if somebody's mouth were moving and the sounds coming out of it were offset by even the tiniest bit of time. It looks weird.

Jennifer Groh: It looks totally weird.

Andrew Huberman: It looks totally weird. Like, this video-

Jennifer Groh: Yeah.

Jennifer Groh: It's uncomfortable.

Andrew Huberman: Yeah, somebody ripped this video from the internet, and there's a time delay.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: But we easily merge what we see with sounds.

Jennifer Groh: Yeah.

Jennifer Groh: That's right.

Andrew Huberman: But maybe talk about this, because now I'm realizing, if I sit and watch a movie in a movie theater or on a big screen or on my computer, the sound is not coming from the screen.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: It's coming from a speaker, which is projecting vertically.

Jennifer Groh: Yes.

Andrew Huberman: How does that work?

Jennifer Groh: Well, not only that, but the sound is jumping around in your perception as different people on the screen from different locations on the screen are speaking.

Andrew Huberman: Right, and they're both coming in through your ears or through the speaker.

Jennifer Groh: Whatever means the sound is being delivered to you is not changing as the different people are speaking.

Andrew Huberman: Right, so let's say a dialogue on a screen between two characters and then maybe there's an explosion in the background, or another character walks in the room, that the source of the sound for us, whether it's a computer or speakers in the room or a movie theater or earbuds, is always constant, but we can quickly move the sound with our eyes, or our eyes move the sound with our ears?

Jennifer Groh: Right.

Jennifer Groh: Right.

Jennifer Groh: Right.

Jennifer Groh: Yeah. Let me amend a little bit here because it depends a lot on how the sound is mixed. They can put in some spatial cues, but if they haven't done that, then what we just said applies. And I think some of my favorite videos for really appreciating this are videos of actual ventriloquists working with their puppets.

Jennifer Groh: Because there they are, the puppeteer is speaking, and they're making it seem like the puppet is speaking, and they're making our perception switch back and forth from their own face to the puppet face, back and forth, depending on what they're actually saying.

Andrew Huberman: So this is a ventriloquist that says, "Hey, Cornelius, how are you?" And then Cornelius says... But the same person says, "I'm doing great," you know?

Jennifer Groh: Yes.

Jennifer Groh: Yeah. So one of these days I've got to learn to do this.

Andrew Huberman: And they probably move their lips a little less when they do that?

Jennifer Groh: Yeah, they try to speak like this without moving their lips too much.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And they sometimes will do a trick of, like... There are certain sounds that you just cannot make without closing your lips in front, and that's really hard to fool people about.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So, for example, if it's a word that begins with a B or has a B in it, they might subtly just cover their mouth a little bit while they're making that B sound so that it's a kind of misdirection like a magician would do to sort of keep you from attending too much to the ventriloquist and throw your attention over to the puppet.

Jennifer Groh: So our perception can switch back and forth between where our brains are telling us, "This is the most likely candidate for the source of this sound, so I'm going to override what my ears are telling me to perceive the sound as coming from here versus here."

Andrew Huberman: Is this something we learn during development?

Jennifer Groh: Partly, yes.

Andrew Huberman: Like, do kids come into the world understanding how to merge sight and sound, or is that a learned phenomenon?

Jennifer Groh: Absolutely.

Jennifer Groh: It has to be learned, and it has to be continuously updated during the course of development until you reach your adult body size. So let me back up a little bit and talk about how we localize sound, especially when we're not talking about screens and videos and movies and whatnot, but just out there in the real world.

Jennifer Groh: The way we tell where a sound is coming from is by the physics of the world causing differential delays for the sound to arrive at one ear versus the other. So sound takes a certain amount of time. You know, a sound coming from over here will get to this ear before it gets to this ear, and it'll be slightly louder in this ear than in this one.

Andrew Huberman: Because it's just closer to that ear.

Jennifer Groh: It's closer, but also there's a kind of acoustic shadow cast by the head.

Andrew Huberman: Mm.

Jennifer Groh: So the sound wave has to kind of come and then go around, and there's a little sort of dip in the sound intensity cast by the shadow of the head. I like to think about the timing cues because they're really easy to calculate. So if you know how far apart your ears are, and you know what the speed of sound is, then you can figure out what the delay is for the sound to reach this ear after this ear.

Andrew Huberman: Mm.

Jennifer Groh: I often take off my glasses to measure the distance between my two ears that way.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And it's something like about a half a millisecond, is the largest delay you can experience.

Andrew Huberman: Half a millisecond.

Jennifer Groh: Half a millisecond. So this is tiny, and that is for the difference between a sound here versus a sound here.

Andrew Huberman: So something from your right versus from your left.

Jennifer Groh: Exactly.

Andrew Huberman: Yeah.

Jennifer Groh: We can obviously detect much smaller sound separations than just totally left versus totally right.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So it's an incredible feat of computational power by the brain. I think maybe we should tell the audience why your brow is furrowed, and I'm excited about this.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Because half a millisecond is less than the duration of a single action potential.

Andrew Huberman: Right, and we should just remind people, action potentials are the electrical signals that neurons use to communicate with one another. These are the fundamental ways in which our brain works. Without these, we're dead.

Jennifer Groh: Right.

Jennifer Groh: It's the fundamental medium of communication in the nervous system, as you say.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So it would seem totally weird for us to be able to process sensory information that is faster than the duration of that minimum increment of firing. You know, there's some research about how exactly this can be done, and it involves things like lots of neurons firing together and really precise synapses that cause minimal delay and very high temporal precision as the signals are going from one neuron to the next.

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Andrew Huberman: So, if my finger snaps with my right hand, which is what I just did, intuitively, I know that it's my right hand because I did it. But my brain expects that sound to arrive more quickly to my right ear than my left ear.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: And yet, for things directly in front of me, right at my nose, the idea that it's right in front of me, let's say, with my eyes closed, I know to look in front of me. I know to expect it in front of me once I open my eyes.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: Are there conditions where we think we hear something from one location, but it's actually arising from another location that's outside an experimental context?

Jennifer Groh: Absolutely. So if you have hearing loss in one ear only, then it's very difficult to localize sound.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Hmm.

Jennifer Groh: It's not completely impossible. You would imagine that it would be completely impossible if the hearing loss was complete and if this timing difference and level difference were the only cues that we use.

Andrew Huberman: Mm-hmm.

Jennifer Groh: But actually, the ear has these little folds in them, and the folds filter the sound as it comes in and in particular, it alters the frequency content of the sound.

Andrew Huberman: Really? So these little dimples inside my ears are useful for something.

Jennifer Groh: Yeah.

Jennifer Groh: They're useful, and your ears are different than my ears.

Andrew Huberman: Hmm.

Jennifer Groh: And so you are going to be expecting a slightly different kind of fingerprint of what the sound sounds like as a function of location than I would be.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Do people with damage to their ears have issues hearing?

Jennifer Groh: Have issues with that?

Andrew Huberman: I mean, it sounds like they sort of must. But like the people I know that roll jiu-jitsu, the wrestlers, their ears are always beat up.

Jennifer Groh: Yeah.

Jennifer Groh: Oh.

Jennifer Groh: They're mashed. Okay.

Andrew Huberman: They basically don't have these folds. It's just kind of-

Jennifer Groh: Flattened?

Andrew Huberman: Yeah.

Jennifer Groh: Interesting.

Andrew Huberman: Yeah.

Jennifer Groh: I don't know of any studies, but I think we can predict from first principles that they would have an initial deficit, and that very likely they would learn to adapt, and they would kind of learn their new set of ears and what particular frequency pattern to expect from that.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Andrew Huberman: If the auditory system is so sensitive, why is it that I don't really hear my own voice?

Jennifer Groh: Mm.

Andrew Huberman: Or if I talk out one side of my mouth, I sort of know I'm doing it, but it doesn't throw me off.

Jennifer Groh: Okay.

Jennifer Groh: Doesn't sound quite right. Yeah, yeah.

Andrew Huberman: Doesn't throw me off.

Andrew Huberman: And yet, most people have the experience of watching themselves or hearing themselves speak, and it feels awkward.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: We don't really like it.

Jennifer Groh: Yeah.

Andrew Huberman: I suppose there are some people on the planet that like to hear themselves speak, but most people don't.

Jennifer Groh: Yeah.

Andrew Huberman: Most people are not...

Jennifer Groh: Right.

Andrew Huberman: It's like we cancel ourselves out while we speak.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: But then when it's coming at us from the front, it's odd.

Jennifer Groh: It's weird.

Jennifer Groh: Do you like listening to this podcast, or do you-

Andrew Huberman: Well, I listen to all the podcasts to see ways that I can improve.

Jennifer Groh: Yeah.

Andrew Huberman: And I like the content that my guests bring on, and I like the topics.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: But it's an awkward feeling, isn't it?

Andrew Huberman: Oh, it's always awkward.

Jennifer Groh: To listen to yourself is very awkward.

Andrew Huberman: Yeah, it's uncomfortable.

Jennifer Groh: It's uncomfortable.

Jennifer Groh: Yeah, yeah.

Andrew Huberman: It's uncomfortable.

Jennifer Groh: Before I answer that question, which is a really interesting question, I want to loop back to the, 'Do we have to learn this?' The other thing to say about learning how to interpret the timing difference cues and the level difference cues, is that a baby's head is about half the width of an adult's head.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So that means that that half-millisecond for me is a quarter of a millisecond for a baby, and it's going to change as they grow. So that's why you have to do all this learning.

Andrew Huberman: Mm-hmm.

Jennifer Groh: With respect to the question you just asked about why our voices sound weird, I can say more about why they sound weird and less about why we experience it as kind of unpleasant.

Jennifer Groh: Maybe that weird and unpleasant connection is because we're just so used to the way we experience it, that to hear it recorded is going to be unfamiliar and strange. I think there are going to be three things. Number one, the recording is not going to capture the full spectrum of frequency content of your voice.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Number two, your brain has an active mechanism for manipulating the transduction of sound in your ears. That is to say, the conversion of sound into a neural signal that's going to go into the brain. So your brain actually controls that process.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And there's some thinking that it's turning down the volume just before you speak so that you don't get blasted by the sound of your own voice.

Andrew Huberman: Hmm.

Jennifer Groh: If you think about it, if I were speaking at this volume with my mouth this far away from my ear, like if I was speaking at this volume from here, or somebody else was speaking at this volume from here, it'd be too loud.

Andrew Huberman: Yeah.

Andrew Huberman: Right.

Andrew Huberman: Got it. So for those just listening, Jenny's referring to... So the distance between your mouth and your ear is a very short one, and if someone were to speak into your ear at that distance, I suppose, unless they were telling you something you really wanted to hear, you would probably feel like, "Hey, get out of my personal space."

Jennifer Groh: You would want somebody to speak a little more softly.

Andrew Huberman: Yeah, and yet we're doing it all the time.

Jennifer Groh: All the time.

Andrew Huberman: It's just that we're projecting it outward.

Jennifer Groh: Well, we're projecting it outward, and our brain is turning down the volume in anticipation of what we're saying.

Andrew Huberman: Hmm.

Andrew Huberman: Got it.

Jennifer Groh: So potentially, it could be a very precisely timed volume knob that is going with each little word that I say.

Andrew Huberman: Mm-hmm.

Andrew Huberman: So when the psychologists say that we can't speak and hear at the same time, they're 100% accurate?

Jennifer Groh: Yeah.

Jennifer Groh: Probably.

Andrew Huberman: We can't speak and hear correctly.

Jennifer Groh: We cannot. And then the third thing is that, this maybe goes back to the first point about the recording doesn't capture all of it, is that some of what we are picking up is actually through bone conduction. You may have bone conduction headphones. I certainly do. These are headphones that don't go over the ears. They don't go in the ears.

Jennifer Groh: They're usually positioned right in front of the ears, delivering the vibration signals to the bone right in front of your ear, and that can get transmitted into your ears as well.

Andrew Huberman: You have these headphones?

Jennifer Groh: I have these-

Andrew Huberman: Why do you use these instead of in-ear earbud-

Jennifer Groh: In-ear?

Andrew Huberman: Yeah.

Jennifer Groh: Because it leaves my ears open, so I can hear something else. So it's safer if you're out exercising somewhere where there might be traffic or something like that.

Andrew Huberman: Mm-hmm.

Andrew Huberman: I get a lot of questions about headphones and safety, and one thing that we resolved recently on the podcast, we had a guest on who is our chair of otolaryngology at Stanford, and she said that if your headphones are loud enough that somebody besides you can hear that there is a sound, not even the specific sounds, you are inflicting hearing damage.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: Probably permanent hearing loss at some level, that she sets a pretty low threshold for, kind of like, be careful, but it seems important given that we now know hearing loss is correlated with dementia.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: It makes sense. Less sensory information comes in, the brain probably says, "Oh, well, there's less stuff coming in," and starts turning off circuits, and then memory goes, and attention goes, and there are other things, obviously, that can impact dementia.

Jennifer Groh: Right.

Andrew Huberman: So it's interesting. The other question I get a lot is about the Bluetooth earphones. People want to know, are they safe? Is it safe to have this Bluetooth arc in your ears?

Jennifer Groh: Mm-hmm.

Jennifer Groh: In your ear.

Andrew Huberman: And we had a guest on here, Matt MacDougall, who is a neurosurgeon at Neuralink.

Jennifer Groh: Mm-hmm.

Andrew Huberman: They're big on Bluetooth at Neuralink.

Jennifer Groh: Mm-hmm.

Andrew Huberman: But he said that the amount of radiation coming from those Bluetooth headphones is considerably lower than the sort of radiation that you're exposed to all day, every day, so he wasn't concerned.

Jennifer Groh: Mm.

Andrew Huberman: Are you aware of any impact of heat? I'm not looking to go after EMF here if there isn't anything there.

Jennifer Groh: Yeah.

Andrew Huberman: But of heat or of just having EMF around your ears.

Jennifer Groh: Yeah.

Jennifer Groh: Around your ears.

Andrew Huberman: Given the sensitivity of the bone, I mean, I'm just amazed that you can pick up sound from the bone vibrations.

Jennifer Groh: Yeah.

Andrew Huberman: I mean, this is a very sensitive neurosensory space, is what I'm realizing.

Jennifer Groh: Yeah

Jennifer Groh: Right. I do think that there are concerns about just how much sound exposure people are accumulating.

Andrew Huberman: Mm-hmm.

Jennifer Groh: If we live long enough, 80% of us will get hearing loss at some point in our lives.

Andrew Huberman: Bummer.

Jennifer Groh: So it's a big problem.

Andrew Huberman: Mm-hmm.

Jennifer Groh: There's certainly concerns that young people are farther along on that trajectory to hearing loss than people from older generations were at a comparable age.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Just because the earbuds are in from morning to night, and the volume is turned up loud enough to block out surrounding sound if you're in a loud environment.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I would encourage people to give some consideration to noise-canceling headphones and to not have the volume be turned up too loud.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm. I'd like to talk about the experience of listening to something, music, let's say, through headphones versus in the room.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: We don't think about it too often, but it's a totally different experience. In one case, you're hearing the sound in your head.

Jennifer Groh: Yeah, right.

Andrew Huberman: Or even your phone on speaker versus wearing your earphones.

Jennifer Groh: Right.

Andrew Huberman: The person's voice or the music is in your head as opposed to in the room.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: And once you think about this difference, I simply can't go back.

Jennifer Groh: Uh-huh.

Andrew Huberman: It's like a-

Jennifer Groh: You like the full, actual speakers, or-

Andrew Huberman: No. Well, now I try to listen to music in the room.

Jennifer Groh: Or you like it in your head?

Jennifer Groh: Yeah.

Andrew Huberman: I find that to be a better experience for me.

Jennifer Groh: Yep.

Andrew Huberman: But when I hear things with headphones, I now feel like, "Oh, the sound is coming from inside my head," and it's a little weird.

Jennifer Groh: Yeah, yeah.

Andrew Huberman: I don't like it so much.

Jennifer Groh: Yeah, right. It is possible to make sound that is coming from headphones sound like it is coming from outside, but to do that, you have to use all three of these sound localization cues. Things have to have an appropriate timing difference and an appropriate level difference across the two ears, and to use the frequency filtering properties of the ear. And since everybody's ears are a little bit different, that last step is really hard.

Andrew Huberman: But there is 3D sound, right?

Jennifer Groh: Yeah.

Andrew Huberman: Like, three-dimensional vision is simple for people to think about.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: As long as they're sighted, you understand that you expect things that are closer to you to be larger than if they were far away.

Jennifer Groh: Mm-hmm.

Andrew Huberman: We learn this without-

Jennifer Groh: Wow, you've got so many wonderful cues to distance in vision, right?

Andrew Huberman: Yeah.

Andrew Huberman: Yeah. Yeah, things in the distance are harder to resolve as opposed to things up close, which you can see all the detail.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: And there are all these cues, right, that we could talk about.

Jennifer Groh: Right.

Andrew Huberman: But since we're talking about hearing, the sounds that we hear at a given level, we know are coming from objects that are actually close or far away, usually based on what we see.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm. Yeah.

Andrew Huberman: Right? So what is 3D sound?

Jennifer Groh: Yeah.

Andrew Huberman: How do I know the difference between a sound that's right in front of my face versus far away with my eyes closed?

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: How do I know?

Jennifer Groh: This is a computational process in the brain that we don't fully understand, and it's worth thinking about, what are the available pieces of information that you could use? Sound is much more bendy than light is.

Andrew Huberman: Bendy.

Jennifer Groh: Bendy, like it bends, right?

Andrew Huberman: Goes around things.

Jennifer Groh: It goes around things, whereas light is just kind of like a straight shot, you know? You don't have the opportunity to use the same kind of information for sound depth that you do for vision.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Even though you have two ears, you can't form an image and check to see whether or not the images line up, which is what stereo vision is.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: You don't have occlusion cues. That is to say, one thing being in front of the other blocks your ability to see the thing that's behind.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So, the sound can go around objects. So there are a few different cues that we can use. One is simply how loud is the sound?

Andrew Huberman: Mm-hmm.

Jennifer Groh: Things that are farther away are going to sound quieter, but you have to know what the sound volume was out there in the world in order to interpret whether or not that is quiet or loud.

Andrew Huberman: Let's use thunder as an example, because thunder sounding very loud predicts lightning that might hit you.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: Thunder that sounds way off in the distance, if you have an understanding of thunder and lightning, predicts a lower probability of you getting hit by lightning.

Jennifer Groh: Right.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: I had this experience recently. I got caught in a sudden thunder-lightning storm in Austin, Texas, and it was coming down in sheets, and then the thunder gets louder and louder, and you're like, "Wow!" And then the lightning gets brighter and brighter, and you think, "I could get electrocuted." And it seems like a low-probability event.

Jennifer Groh: Right. Depending on where you grew up, you might have learned as a child some basics of how to tell when it's a good idea to get to shelter.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So, for example, I was taught growing up you count one-one-thousand, two-one-thousand, whatever. As long as you can count to five seconds, you're probably okay. But once you're getting to that level, you should maybe go inside.

Andrew Huberman: There, take that one in, folks, from somebody who grew up with them. You see the flash of lightning-

Jennifer Groh: Yeah.

Jennifer Groh: One-one-thousand, two-one-thousand, three-one-thousand, four-one-thousand, five-one-thousand. And if it takes longer than that before you hear the thunder, you're okay. But at that point, I would go inside.

Andrew Huberman: You may have saved some lives. Yeah. Growing up in California, we didn't learn anything about it.

Jennifer Groh: You didn't get that, and people who grew up in cities wouldn't have gotten this.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I think in cities, it's actually very hard to see the connection between the lightning and the thunder.

Andrew Huberman: Mm-hmm.

Jennifer Groh: But I grew up in rural Vermont, and it was, like, very obvious.

Andrew Huberman: Mm-hmm.

Jennifer Groh: You know?

Andrew Huberman: I grew up in the San Francisco Bay Area, and I've been through so many earthquakes, and one of the things that people don't realize if they've never been in a major earthquake is that it's extremely loud. It starts with sound, not shaking.

Jennifer Groh: Yeah.

Jennifer Groh: Sure.

Andrew Huberman: So people are always saying, "California earthquakes," and with the '89 quake, the Embarcadero Freeway pancaked, and the Bay Bridge, actually, a segment fell out.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: People forget this, during the World Series. If that happened now, there would be so many casualties, but it was a lot less busy in the Bay Area back then.

Jennifer Groh: Yeah.

Andrew Huberman: The first thing that happens in an earthquake is it sounds like a train is about to come through the room.

Jennifer Groh: Yeah, sure.

Andrew Huberman: And then the shaking starts shortly thereafter.

Jennifer Groh: Uh-huh.

Andrew Huberman: But the sound always comes first.

Jennifer Groh: Huh.

Andrew Huberman: I always tell people this when they're afraid of earthquakes.

Jennifer Groh: Yeah.

Andrew Huberman: Like, you'll hear it before you'll feel it.

Jennifer Groh: Before you feel it, yeah.

Andrew Huberman: So if it sounds like a train is going to come through the room, you're probably about to have an earthquake.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Jennifer Groh: I think elephants use sound to communicate over long distances.

Andrew Huberman: That's cool. They stomp?

Jennifer Groh: Yeah, I think so, or they can hear things, and I think they have sensors in their feet that can pick up these vibrations that we might call sound.

Andrew Huberman: Oh, that's cool.

Jennifer Groh: Yeah.

Andrew Huberman: That's like that scene in "Stand By Me" where they're crossing the train tracks on a bridge.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: And all the kids are just kind of moving along, and then Gordie, who's arguably one of the smarter in the bunch.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: He's reaching down and holding the tracks, and he feels the tracks shakes before he-

Jennifer Groh: He's feeling the...

Jennifer Groh: He feels it.

Andrew Huberman: ... hears the horn, and then, of course, the smoke rounds the corner, the train rounds the corner.

Jennifer Groh: Hears it. Yep.

Jennifer Groh: Yep.

Jennifer Groh: Interesting. Interesting.

Andrew Huberman: Yeah.

Andrew Huberman: Yeah.

Jennifer Groh: And with the elephants, I'm not sure. I think maybe it's not sensors in the feet, but bone conduction from the feet to the ear.

Andrew Huberman: Hmm.

Jennifer Groh: And that's where it's being picked up. So, okay, your question was, if I can go back to your question, it was about distance, and how do we know how far away a sound is coming from?

Andrew Huberman: Interesting.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So, the loudness cue requires you to know something about how loud the original stimulus at the source is.

Andrew Huberman: Hmm.

Jennifer Groh: And so, thunder's a wonderful example of this because we do have quite a bit of experience with thunder, so we can kind of use how loud it is as a good cue, and it also works great because we're talking about really long distances, right? There's another pretty cool cue that you and I are probably using right now, and that is that the sound in this room is bouncing off of all the different surfaces.

Jennifer Groh: So, the shortest path copy of the sound is coming straight from your mouth to my ears.

Andrew Huberman: Mm-hmm.

Jennifer Groh: But in addition, there's a copy that's bouncing off of the table that's between us. That has a longer path length, so it'll be slightly delayed. There'll be another copy that's hitting the ceiling and coming down to my ears.

Andrew Huberman: Oh, this is weird.

Jennifer Groh: And that is going to have an even longer delay. I'm completely unaware of this, but my brain is probably using the slight differences and the kind of pattern of slight differences to figure out that you're about seven feet away from me.

Jennifer Groh: If we were closer to each other, the difference between that straight path copy and the copy bouncing off of the table would be greater than it is right now. Because at this angle, with this geometry, there's really not that much difference, so the bounced off copy and the straight path copy are pretty similar.

Andrew Huberman: Hmm.

Andrew Huberman: I never thought about this.

Jennifer Groh: It's incredible, right?

Andrew Huberman: This is a way that vision is so different.

Jennifer Groh: Yeah.

Andrew Huberman: I came up through vision science, mostly.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah, so did I.

Andrew Huberman: And right, I mean, there are certain wavelengths of light that can pass through our body, like long-wavelength light.

Jennifer Groh: Yeah.

Andrew Huberman: That's relatively new findings. I think it's really interesting, and it's very healthy for us, it turns out, mitochondrial health, et cetera.

Jennifer Groh: Yeah.

Andrew Huberman: But, in general, we're not used to thinking about light and wavelengths of light going through things, unless they're translucent or transparent, like a window. Sound is constantly bouncing off everything.

Jennifer Groh: We're in a hall of mirrors for sound all the time.

Andrew Huberman: But you experience me, and I experience you during this conversation as one coherent sound. Even though we are biologically poised to detect half a millisecond differences in the arrival time of the two ears, there are much greater differences in the arrival time of my voice bouncing off the table versus the walls versus the ceiling versus the direct path, but you integrate them.

Jennifer Groh: And I don't hear you as saying the same thing five different times, right?

Andrew Huberman: Right.

Jennifer Groh: You know, it's one integrated whole.

Andrew Huberman: And closing one's eyes doesn't change that. If I close my eyes, and you speak, I can register the direct path.

Jennifer Groh: Right.

Andrew Huberman: I infer that you're right in front of me. Of course, I know that because my eyes were open a second ago. But all the versions of your voice arriving, bouncing off the different surfaces, are arriving at my ears, and it's not confusing, and it's not jarring.

Jennifer Groh: Right.

Andrew Huberman: Like, if somebody came over and touched my arm, and I felt it on my arm, but also a little bit on the back of my neck, and a little bit on my knee, that would be weird. That would be odd. You know, and we can get these sensations. There are certain places on the back, for instance, that you can feel a subtle kind of phantom touch in your foot because of the way the neural circuits are organized. And with pain, we talk about this as referenced pain.

Andrew Huberman: You know, for internal organs, there are branches of the nerves such that... And this shows up in Eastern medicine, but also Western medicine, like someone with liver pain will register that in their shoulder, you know?

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah.

Andrew Huberman: And we think, "Oh, this is crazy."

Andrew Huberman: No, it's not crazy. There's actually branches that support that referenced pain. But we don't do this with hearing.

Jennifer Groh: Yeah.

Andrew Huberman: We shut it all down, and we just draw a conclusion.

Jennifer Groh: Right.

Andrew Huberman: Wild.

Jennifer Groh: It's wild, isn't it?

Andrew Huberman: It's totally wild. Are you about to tell me that our voices are also causing vibrations in the objects around us, and that we just can't detect them? Why are we not like the elephants? How come we-

Jennifer Groh: Maybe we are like the elephants. I don't know.

Andrew Huberman: Is it the case that low-frequency sounds can travel further with respect to our ability to detect them?

Jennifer Groh: Mm-hmm.

Andrew Huberman: So, I don't want to get into a conversation about frequency of sound and intensity, and high versus low frequency, because that's really about the physics of sound.

Jennifer Groh: Yeah.

Jennifer Groh: Right, right.

Andrew Huberman: But ultimately, we filter the physics of sound through our nervous system. So, if I want to signal to somebody far away, I would probably want a big bass drum or a gong. I would not try to whistle to them far away. Or if I could pick a horn that was a deep, like, "awwng" versus, "eeee."

Jennifer Groh: Mm-hmm.

Andrew Huberman: I'd want bass.

Jennifer Groh: So, there are a few things wrapped up here. One is that the lower frequencies bend more easily, so they can go around these objects better. So, if you're talking really long distances, you know, the odds that there's something in the path that you want the sound to go around go up.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Another thing that's wrapped up here is that we tend to lose high-frequency hearing before we lose low-frequency hearing.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And so, the lower frequencies are audible to more people and are louder to people than the higher frequencies.

Andrew Huberman: So, you're saying it's because it can bend around objects?

Jennifer Groh: Well, I don't really know what the choices that are being made are by the people whose job it is to figure these kinds of things out. But I'm sure that there's some thought being given to the receiver, you know, the people, and what they can perceive.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So, let's take a couple of other examples of warning systems that humans use. The gas in a gas stove doesn't have an intrinsic odor to it.

Andrew Huberman: Mm-hmm.

Jennifer Groh: There's an odorant that's been added.

Andrew Huberman: That rotten egg, sulfur smell.

Jennifer Groh: That rotten egg, yeah, exactly. And so, you know, that was chosen a long time ago to be added, and it turns out to be a good thing because it doesn't really smell like anything else. It's not pleasant, but everybody can detect it. I don't know of any cases of people who can't smell that, unless they have a generalized anosmia, where they can't smell anything.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Traffic lights are maybe a little bit of a less of a win, because you've got red versus green. And 6% of the population is red/green color blind, which operationally means not that you can't see a red stimulus or a green stimulus, but that you can't tell the difference, you know, whether or not something is red or green.

Andrew Huberman: Yeah, I should just say that most red/green color blind people tend to be males, just because of where the gene mutation is in the genome, and they don't see...

Jennifer Groh: Yes.

Andrew Huberman: People always want to know, like, what does red look like to them?

Jennifer Groh: Yeah.

Andrew Huberman: Red and green look kind of more orange-ish, burnt brown, orange color, and dogs see the world that way all the time.

Jennifer Groh: Right, so if you do a color-matching experiment, my understanding is something along the lines of people with red/green color blindness will map both red and green onto yellow.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And not be able to tell the difference.

Andrew Huberman: Yeah, that's right.

Jennifer Groh: It's not the kind of cartoon view of, like, it looks black and white.

Andrew Huberman: There are people who are completely monochromatic, but it's very rare.

Jennifer Groh: Very rare.

Andrew Huberman: Very, very rare.

Jennifer Groh: Yeah.

Andrew Huberman: And there are other forms of color blindness that are more subtle. And we'll put a link to this. Jay and Maureen Neitz, up at the University of Washington, have a terrific... They run a color vision lab.

Jennifer Groh: Mm-hmm.

Andrew Huberman: She's a molecular biologist, he's more of a psychophysicist. And they have some really great color vision tests there that people can take, and many people find that they have subtle color vision deficits.

Jennifer Groh: Yeah, yeah, exactly.

Andrew Huberman: But they don't consider themselves fully color blind. But every once in a while... Monochromats usually know that they're seeing the world in black and white.

Jennifer Groh: Yeah, monochromats...

Jennifer Groh: Right.

Jennifer Groh: And a lot of what is under this heading is really more an anomaly than a complete absence of an ability to distinguish red from green. But back to our traffic lights. So, you got your red versus green signaling something very different. And most places have those lights oriented vertically, which gives you a second cue to what needs to be conveyed here.

Andrew Huberman: Not the same light switching.

Jennifer Groh: Right. It's not the same light switching, and one is on top, and the other's on the bottom.

Andrew Huberman: Mm-hmm.

Jennifer Groh: It's more of a problem when in some intersections, the set of three lights is oriented horizontally.

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Andrew Huberman: So, really what we're talking about, that I'd like to drill into even deeper, cross-senses, but primarily with sound, is, you know, how space, how the physical environment shapes our perception of things.

Jennifer Groh: Yeah. Yeah.

Andrew Huberman: And I'm also very interested in the relationship between vibration and sound, given that our ears contain the apparatus to detect sound frequency, but also, have to do with balance and vibration.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Most of us have had the experience of someone pulling up next to us in a car, blasting bass really loud, and our windows start shaking, and their windows start shaking.

Jennifer Groh: Oh, yeah.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: Could we talk just about how objects have a resonant frequency?

Jennifer Groh: Right.

Andrew Huberman: I think this is pretty interesting, and then people will inevitably want to know about how humans have a resonant frequency, and we do.

Jennifer Groh: Right.

Andrew Huberman: I believe that certain frequencies of sound can shape our emotional state.

Jennifer Groh: Oh, sure. I mean, that's music, right?

Andrew Huberman: For example, right.

Jennifer Groh: For example.

Andrew Huberman: It just, for some reason, when we break it down to one frequency, and it's not packaged in music, people somehow think it's, like, "woo" or mysticism, and it's not.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: I mean, I'm fascinated by this, like, the "gongs" as an ancient tool for trying to orient people's emotional state or signal.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Like, if we hear "dong, dong, dong," it sounds ominous, right?

Jennifer Groh: Mm-hmm.

Andrew Huberman: If we hear chirping of birds, we know they're birds, but if we hear light, you know, in the Disney movies...

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: It's been a long time since I've seen a Disney movie, but the kind of the stuff of fluttering is high frequency. High-frequency movement tends to be high-frequency sound. So, how do you think about the relationship between frequency and emotion and resonant frequency? I mean, it's a vast landscape, but I'd love your thoughts on this.

Jennifer Groh: Yeah.

Jennifer Groh: So, can we go into the music realm to talk about this?

Andrew Huberman: Please, I think that's intuitive for many people. Yeah.

Jennifer Groh: Okay.

Jennifer Groh: Okay, good. So, one of the things that I think is fascinating about music is that it's universal, and nobody really knows what it's for. Like, it's pretty clear that language is useful to us.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Right? It helps us exchange information.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So, pretty obvious that language is a benefit, a survival benefit for individuals and for the species as a whole.

Andrew Huberman: Mm-hmm.

Jennifer Groh: We don't really have as clear a view of why music... You know, what role did music play in our success in evolution, natural selection?

Andrew Huberman: Mm-hmm.

Jennifer Groh: You know, music really is universal. Every human culture has it. There is some variation as to whether or not a culture embraces melody, embraces harmony, but every culture has rhythm. You can't have melody or harmony without rhythm. It doesn't make any sense, right? Like, imagine a familiar tune like "Happy Birthday," but the duration of the notes was completely arbitrary, you know?

Andrew Huberman: Yeah, it would sound crazy.

Jennifer Groh: It would sound crazy. It would not be recognizable to us as "Happy Birthday," but you can play it fast, you can play it slow, you can pitch shifted up or pitch shifted down, musical terms, in a different key, and we would recognize that as a particular song. So, that's what I mean about rhythm being really critical.

Jennifer Groh: And the criticality of rhythm offers up the following, kind of, wild theory. This is not my theory. I wish I could quote who's ever theory it is. But it is that perhaps what music and rhythm is for, is to help us act in concert with one another, and be louder than any of us could be by ourselves, and to scare off predators and competitors.

Andrew Huberman: Hmm.

Jennifer Groh: So, for example, imagine a pack of hyenas are surrounding a kill from a lion. The lion has long since sated and has gone away, but now a bunch of scrawny humans want to scare off the hyenas.

Jennifer Groh: If they go after the hyenas, all stomping their feet together and shouting together, it's going to be a lot louder than any one person could do by themselves.

Andrew Huberman: Oh, I like this theory.

Jennifer Groh: It's kind of nice, right?

Andrew Huberman: I'll tell you why in a moment, but please continue.

Jennifer Groh: And then, that kind of concerted working together as a group, and you could sort of see that once you have the basics of... And here I'm talking, when I say once you have... I'm really imagining on an evolutionary scale that for anything to come about and endure, requires that it increase our fitness at every stage of the way.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So initially, you might get that rhythm thing going on, but then, that would be satisfying to people. Like, if you had a mutation that made acting together feel good for some reason, and then it would come along with this benefit of competing with the hyenas for the lion kill. And then it would kind of potentially feed on itself of like, well, even more cooperative action, feeling good together, allows us to then do other things together that we can't do individually.

Andrew Huberman: Have you ever seen the... It's a song, and I don't exactly know what to call it. The chanting and the song of Maori in New Zealand?

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah.

Andrew Huberman: They'll do this before rugby games.

Jennifer Groh: Oh, right, the-

Andrew Huberman: Because the All Blacks are one of the best rugby teams in the world.

Jennifer Groh: Yeah.

Andrew Huberman: There's an incredible video that a friend of mine, she always sends this to me when I'll say something like, "Oh, you know, what do you think of something that was on the news or something?"

Jennifer Groh: Uh-huh.

Andrew Huberman: And she'll send... There's an incredible case in the government in New Zealand. I don't know whether they use parliament or what.

Jennifer Groh: Mm-hmm.

Andrew Huberman: There's an example of... So okay, I'll just say it how it is.

Jennifer Groh: Yeah.

Andrew Huberman: Some white politician reads out some proclamation, maybe that's up for a vote, and then all of a sudden, it will start in one corner of this very majestic, government building.

Jennifer Groh: Yeah.

Jennifer Groh: Yes.

Andrew Huberman: Looks sort of like our Congress, but it's different.

Jennifer Groh: Right.

Andrew Huberman: And she'll start chanting, and then it's, like, wide eyes.

Jennifer Groh: Mm-hmm.

Andrew Huberman: There's no blinking.

Jennifer Groh: Mm-hmm.

Andrew Huberman: It's very interesting, and there's stomping, and there's clapping, and then all of a sudden, other people start joining in with her.

Jennifer Groh: Right.

Andrew Huberman: And you're like-

Jennifer Groh: And it gets really loud when they're together.

Andrew Huberman: You know a number of things immediately. A, they're pissed. Two, they're not going to stand for this. Three, there are a lot of them. And four, like, they're not to be messed with.

Jennifer Groh: They're united.

Andrew Huberman: They're united.

Jennifer Groh: Yeah.

Andrew Huberman: Admittedly, I had to have someone look this up. It's called "Haka." And it's incredible because you immediately understand how these people feel. And it's a, "No, we're not going take that," kind of stance, at least in the context of this government example.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: In terms of pre-rugby match, it's really a display of vigor, and we are primates, after all.

Jennifer Groh: Right. Right.

Andrew Huberman: We are Old World primates.

Jennifer Groh: Yep.

Andrew Huberman: And vigor displays, run through all the Old World primate species, including us.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: I think it's definitely a vigor display.

Andrew Huberman: Like stomping, making one's body big.

Jennifer Groh: Right.

Andrew Huberman: And the lack of blinking is something that, as a vision scientist, I caught onto early.

Jennifer Groh: Yeah.

Andrew Huberman: Like, no one's doing this and blinking a lot. They're showing that they will not break their attention, until this is complete. And somebody not blinking while staring directly at you, is a command for your attention as well.

Jennifer Groh: Mm-hmm.

Jennifer Groh: And it's even in our language, isn't it? So-and-so didn't blink.

Andrew Huberman: That's right. They don't blink. They're not afraid.

Jennifer Groh: Right.

Andrew Huberman: You know, these days, because of the craziness of the political socio-landscape with assassinations and very strong personalities in government and online, and because, in media now, to at least some extent, different form of media, not politics.

Jennifer Groh: Mm-hmm.

Andrew Huberman: But, you know, I'm so intrigued by the idea that some people are capturing people's attention and loyalty, not just by virtue of what they say, but the certainty with which they say it. Now, that's not a new theme, but also, the timbre of their voice, the refusal to entertain dissenting voices.

Jennifer Groh: Yeah.

Andrew Huberman: But also, how a lot of voices are just not the right timbre and frequency, and delivered in the way that these people have obviously mastered their ability to command other people's attention.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Because this stuff hits at a primitive level, right? People aren't necessarily just voting on issues.

Jennifer Groh: Yeah, yeah.

Andrew Huberman: They're voting on feeling. We've known this.

Jennifer Groh: Right.

Andrew Huberman: So in any case, the "Haka" is a beautiful example of what you're describing.

Jennifer Groh: Well, and the other thing is that music plays a role in say, the military and in war. I read somewhere that the military is the largest employer of musicians in this country.

Andrew Huberman: Interesting.

Jennifer Groh: Yeah.

Andrew Huberman: Makes sense.

Jennifer Groh: Well, you know, it was a surprise to me when I first heard it.

Andrew Huberman: Yeah.

Andrew Huberman: Yeah, surprising to me, but, I mean, somebody's got to play Taps.

Jennifer Groh: Yeah.

Andrew Huberman: Usually, that's one one horn, though.

Jennifer Groh: Right, you get one-

Andrew Huberman: Right.

Jennifer Groh: Right. So, I think the other possible angle for all of this is there are things in many species that are not obviously beneficial. Take the peacock, for example, that enormous investment in plumage, in very colorful tail feathers, is not something that is directly adding to the survival skills of the male peacock. But rather, it's something the female peacocks like. And so, that tends to feed on itself, too.

Jennifer Groh: So, that's another way that music could get into our panoply of human characteristics, without necessarily directly leading to something like being able to get more food. Like, the rhythm thing gives us more food.

Andrew Huberman: Mm-hmm.

Jennifer Groh: People who are good at music might end up with more offspring than people who weren't good at music. That would be the sort of general idea behind that part of the theory.

Andrew Huberman: In many, now, older movies, typically, it was a man singing to a woman, or in the movie "Say Anything," John Cusack simply used a boom box, right?

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah, with his big-

Jennifer Groh: Yeah, right.

Andrew Huberman: Or poetry, creative works, but expressed out loud, were the way that courtship took place.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Erich Jarvis was on this podcast.

Jennifer Groh: Okay.

Andrew Huberman: I don't know if you know Erich.

Jennifer Groh: Yeah.

Andrew Huberman: The Rockefeller.

Jennifer Groh: Mm-hmm.

Andrew Huberman: He's a very accomplished dancer. I don't know if you know this, but he was supposed to be in the Alvin Ailey Dance Company.

Jennifer Groh: Yeah.

Jennifer Groh: Mm-hmm.

Andrew Huberman: He decided to become a neuroscientist instead. But as I understand, he's still a good dancer.

Jennifer Groh: Yeah.

Andrew Huberman: And he was saying that he thought that perhaps primitive vocalizations evolved first.

Jennifer Groh: Mm-hmm.

Andrew Huberman: So, vocalizations of disgust, or pleasure, or fear, or excitement. Then he thought perhaps, came song and dance.

Jennifer Groh: Mm-hmm.

Andrew Huberman: So, song and body movement, to signal what one was feeling or what their intention was.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And then, perhaps, spoken language came after that. It makes sense. I just think we don't know.

Jennifer Groh: Yeah, we don't know, and I think it's kind of interesting. There are maybe sort of two-- Like, I think with the songbird, they are signaling things like vigor, and fitness, and territoriality, and things like that. They're not conveying something symbolic, whereas the vocalizations in the primate tend to mean something specific.

Andrew Huberman: Hmm.

Jennifer Groh: You know, sometimes I wish I could have a time machine, and I could go back and look at what happened in earlier stages of evolution, and just kind of see, "Well, what is the lineage?"

Andrew Huberman: Mm-hmm.

Jennifer Groh: What is the sequence of events that led us to have language, that led us to have music? Did it come from the same process as songbirds, or did it come from a completely parallel process?

Jennifer Groh: I mean, I think we do see that evolution can arrive at similar characteristics through different means, in different places, and at different times. So, it could be a kind of convergent, parallel process, or it could be something different.

Andrew Huberman: Mm-hmm.

Andrew Huberman: I feel like music conveys intention. Music can tell a story. And music, because of the way that it organizes language, provided there's lyrics into, like, riffs, and motifs, and melodies, and choruses, that it makes it very easy to remember things. I'd like to talk a little bit about the possible neural underpinnings of this. Two things come to mind. First of all, you mentioned the ABCs.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: You know, "A, B, C, D, E, F, G." Almost everybody knows that melody. And it's probably easier to remember all those letters in that form as opposed to A, B, C, D, E, F, G, H, I.

Jennifer Groh: Oh, sure.

Andrew Huberman: Because you break it up. And I'm almost certain this is true, because I have a good friend, and he's a very accomplished musician, and he's an incredible songwriter and lyricist. He's written lyrics for a number of other artists, not just himself. And he has several bands. He writes a song a day.

Jennifer Groh: Right.

Jennifer Groh: Uh-huh.

Andrew Huberman: It's crazy. He released a song a day during the pandemic.

Jennifer Groh: Woah.

Jennifer Groh: Whoa!

Andrew Huberman: Great songs. And occasionally, because I'm such a fan of his music, I'll say, "There's that one song, like, what's that lyric?"

Jennifer Groh: Uh-huh.

Andrew Huberman: And he'll say, "Oh, yeah, no, I don't remember." And then, he'll start, and then he'll remember it. And, I mean, he's got thousands of songs in his library of songs he's written and sings.

Jennifer Groh: Uh-huh.

Andrew Huberman: And I said, "So when you're on stage, how does it work?" He said, "As long as I can remember the first two words or three words of a verse, the rest just kind of spills out of me."

Jennifer Groh: Yeah.

Jennifer Groh: Yes.

Andrew Huberman: I think that's how song organizes language. Because it's very hard to memorize a speech. But you can memorize a song, no problem.

Jennifer Groh: Yeah, and that's my experience, too, that if I know the first couple of words of a verse, I've got the rest of the verse.

Andrew Huberman: Mm-hmm. Yeah, it's so interesting. So in the brain... We haven't talked too much about brain structures yet, but maybe we can do that.

Jennifer Groh: Yeah, right. Yeah.

Andrew Huberman: And not to fill people's minds with names of things, because I always say, like, it doesn't matter if it's called the superior colliculus or the superior schminliculus.

Andrew Huberman: It doesn't matter, unless...

Jennifer Groh: It doesn't matter.

Andrew Huberman: But what's interesting are the properties of these different brain structures.

Jennifer Groh: Right, right.

Andrew Huberman: So, I think about the ears as, you know, separating different frequencies of sound, and then there's a bunch of other important stuff. No disrespect to the auditory neuroscientists.

Jennifer Groh: Mm-hmm.

Andrew Huberman: But, as you said, in the superior colliculus is where hearing, and vision, and the other senses come together. They're mapped onto one another.

Jennifer Groh: It turns out that the story is more complicated and more interesting than that. I got hooked on that particular study that I mentioned at the beginning. So, this was auditory signals in the superior colliculus being affected by the position of the eyes at the time the sound was presented. And now, our audience knows about how sound is localized. We haven't talked that much about how visual information is localized.

Jennifer Groh: I think because mostly that's fairly obvious, that your eye is kind of a little camera, and light hits a particular location on the retina, and that retinal location tells us what the location of the visual stimulus is.

Andrew Huberman: Mm-hmm.

Jennifer Groh: But it tells us the location of the visual stimulus with respect to the direction the eyes are pointing. But our sound localization cues are with respect to, where's the sound with respect to the head. So, this finding that neurons were responsive to sound but cared very much about the position of the eyes was really a startling finding when it first came about.

Jennifer Groh: When I set up my own lab, I basically set out to find out, "Well, where does this computation happen? Where is the brain incorporating information about eye movements into the processing of sound?" We knew from the literature was, "Okay, the superior colliculus is one of the places, but does it happen in the superior colliculus, or does it happen in a different brain area?"

Jennifer Groh: And so we kind of marched along the auditory pathway in brain areas that, I call them part of the auditory pathway, because they're much more closely connected to the ear than to anything else, and because at the time, nobody thought there were visual signals in these areas. We thought it was just auditory. That, too, turned out not to be true. But they're definitely much more auditory than visual.

Jennifer Groh: And what we found was that in each of these areas, eye movements affect the auditory signals there, too, even though they weren't in this convergent structure of the superior colliculus. So, we decided that it would take a long time to march through every brain area, and that it might be worth sort of jumping over a few brain areas and looking in the ear itself.

Jennifer Groh: So, I need to give the audience a little bit more information about what is possible in the ear and why that seemed like a reasonable thing to do. It has some little muscles in it. There are two muscles that control the bones of the middle ear. And then, inside the cochlea, there are cells called "outer hair cells" that can actually expand and contract, just the way a little muscle could.

Andrew Huberman: We should explain. The cochlea is this snail-shaped structure that has, essentially, we call them neurons, but these sensory cells, that vibrate according to the frequency of the sound, and this is critical for our perception of sound.

Jennifer Groh: Yes.

Jennifer Groh: Exactly.

Andrew Huberman: And you have one on each side.

Jennifer Groh: You have one on each side. It's snail-shaped, and it's connected. The vestibular, your balance structures, are also connected to this as well. And to just describe the flow of information, you have got your outer ear, you've got your ear canal, you have your eardrum, you've got these little bones that connect the eardrum to the cochlea. And so, there's muscles that affect the motion of those little bones, and then there's cells inside the cochlea that can also act like muscles.

Jennifer Groh: These structures get input from the brain. So, we thought, well, if they're getting top-down input from the brain, are they getting a top-down input from the brain that carries information about the position of the eyes? It seemed kind of like a wild possibility, but not completely out of left field. Like, there was a possible mechanism here that we could imagine.

Jennifer Groh: And the neat thing about this is that we didn't have to do something, like, stick an electrode into these muscles, because they're attached to the bones and attached to the eardrum. And so, if they were being manipulated by a top-down signal from the brain, they would tug these bones, and that would tug the eardrum.

Jennifer Groh: And when the eardrum moves, normally it moves in response to sound, but if it moves in the absence of sound, it's going to make a sound.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So, you could put a microphone in the ear canal to see whether or not anything was happening in connection with eye movements. And this, too, wasn't out in left field to do this, because there's already kind of known signals generated by these kinds of structures that are measured by clinicians, by audiologists, and otolaryngologists. You can put a microphone in the ear, and you can measure things called otoacoustic emissions.

Andrew Huberman: The base of your ears are making sounds, folks.

Jennifer Groh: Your ears are making sounds, folks.

Andrew Huberman: I know. I know, it's weird.

Jennifer Groh: It's kind of wild.

Andrew Huberman: Some people make more of them than others. Yeah.

Jennifer Groh: Some people make more of them than others, exactly.

Jennifer Groh: So, we wanted to know if any of these little sounds were being generated with eye movements. And I wouldn't be here telling you this story if it didn't turn out that, yes, they do. So, we were able to measure that the eardrum is basically moving in connection with every eye movement, every saccadic eye movement. These are the fast, jerky eye movements. There's other kinds of eye movements, and we haven't yet tested them.

Jennifer Groh: The signal is very precisely time-locked to the onset of the eye movement. And the effect is different in the two ears, so that if your eyes are moving to the left, the eardrum on the right is going to kind of bulge inward, then outward, then inward. I might have this backwards, but whatever the right ear is doing, the left ear is doing the opposite, so that the eardrums are going to be moving in the same direction. One is going to be inward when the other is going outward.

Andrew Huberman: Like a wave.

Jennifer Groh: Like a wave, exactly. Like a wave, not like a-

Andrew Huberman: Not like flapping.

Jennifer Groh: Not like flapping.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Exactly. You know, we're still actually at pretty early days in understanding this process and what it's for. But it's a very precise signal. It turns out to carry information about how far the eyes are moving to the left or to the right, as well as a bit less, but some information about vertical movements as well.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And we think that this may be kind of the first step in that integration of visual and auditory information.

Andrew Huberman: Which would be the critical first step if the major goal of this integration of visual and auditory is for localization of sounds.

Jennifer Groh: Right.

Andrew Huberman: Because, you know, as a neuroscientist there's so many different areas of neuroscience. I used to marvel at-- You know, you go to a meeting, you got people saying consciousness and working on consciousness.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: You have people trying to figure out how a single photoreceptor works or a single hair cell works.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah.

Andrew Huberman: And so, when I think about a sensory system, I think about layers of sophistication and how they likely evolved.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Like, very briefly, I mean, the visual system first evolved to detect light and dark on the order of 24-hours, so you know the difference between nighttime and daytime, which means even with the total inability to see objects, you are safer if you know when to stay in and when to go out.

Andrew Huberman: And then at some point, we evolved the ability to... probably motion detection came before the ability to see detail, because it's way more important to know if something's big, and coming at you big and moving away.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Jennifer Groh: Right. Or help you stay oriented, like with respect to knowing what's up and what's down, and staying upright.

Andrew Huberman: Or-

Andrew Huberman: Right.

Andrew Huberman: That's right.

Jennifer Groh: Yeah.

Andrew Huberman: And just like the falling reflex is probably the most important reflex in the vestibular system to brace yourself, so you have a lesser chance of dying if you fall.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah.

Andrew Huberman: Right? Everyone... you know. If your visual world suddenly goes up very quick, you know you're falling.

Jennifer Groh: Yeah.

Jennifer Groh: Right, right.

Jennifer Groh: Right.

Andrew Huberman: And then comes, you know, additional layers of sophistication, like fine detail, color vision.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Color vision probably evolved last.

Jennifer Groh: Mm-hmm.

Andrew Huberman: At least trichromatic color vision.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And then, so in the auditory system, I think the same thing. You need to be able to know probably, which direction a sound is coming from. Is it low or high frequency? And on and on.

Jennifer Groh: Right.

Andrew Huberman: You know, and so I think about that, like in the motor system, that the oldest we know the evolutionary history of the genes that are expressed in, like, the motor neurons that move the trunk are the same ones that undulating fish use.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm.

Jennifer Groh: Fish.

Jennifer Groh: Uh-huh.

Andrew Huberman: And, actually, this will get us back to sound, I promise.

Jennifer Groh: Uh-huh.

Andrew Huberman: And then these additional layers of motor neurons that have been added through evolution, the ones that flap the fins.

Andrew Huberman: And then the final addition are the motor neurons that control fine movement of the fingers.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: So I have this kind of obsession with this, because if you look at music that's very primitive, right? Like, you just look historically speaking, I'm not casting judgment on music, just historically.

Jennifer Groh: Mm-hmm.

Andrew Huberman: It's rich in bass tones relative to high-frequency tones, and dance that we assign as primitive tends to involve a lot of movement of the trunk.

Jennifer Groh: Mm-hmm.

Andrew Huberman: People aren't just, like, flapping their fingers and toes out there, right?

Jennifer Groh: Yeah. Yeah, yeah.

Andrew Huberman: Now, so as you go from low to high frequency, there's a body map of low to high frequency.

Jennifer Groh: Mm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And actually, when people are making a very detailed point, they'll often point with their fingers, they'll move their fingers.

Jennifer Groh: Mm-hmm.

Andrew Huberman: But when we want to emphasize a big point, we use our whole body.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah.

Andrew Huberman: We put our whole body into it. So, I actually believe that all the sensory systems are mapped to one another in a way that goes from low frequency to high frequency.

Jennifer Groh: Uh-huh.

Jennifer Groh: Yeah.

Andrew Huberman: Intensity is important, and direction is important.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: Me pointing at you, which even feels funny to do because we're on good terms.

Jennifer Groh: Right.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: As far as I'm concerned, we're on good terms.

Jennifer Groh: I didn't blink.

Andrew Huberman: You know, is very different than me standing back. And if I come at you with my whole body, it's very different than if I point a finger, for instance.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Right?

Jennifer Groh: Mm-hmm.

Andrew Huberman: So. I feel like these things probably evolved from this in parallel, and as you pointed out before, they serve an adaptive role.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Right.

Andrew Huberman: So, the fact that position of the eyes can change the way I hear seems wild, and that's a wild thing.

Jennifer Groh: Yeah.

Andrew Huberman: Is the inverse also true? Is where I listen affecting, how my eye... Yeah, where I hear something typically directs my head movement and my eye movement. So this is just the same thing in reverse.

Jennifer Groh: I think it's all part of an integrated system. You know, we talked about the top-down control over the ear, but there's a lot of top-down control over vision, too. And some of it is a little easier to understand than what I just described, because blinking is top-down control over vision. Eye movement's top-down control over vision. Focusing the lens of your eye, right?

Andrew Huberman: Mm-hmm.

Jennifer Groh: That's also top-down control.

Andrew Huberman: Mm-hmm.

Jennifer Groh: There are descending connections from the brain to the retina itself that nobody understands. Apologies to the people working on this. I really want you to keep working on this, but I feel like there isn't a clear theory yet about what exactly these descending connections might be doing.

Jennifer Groh: From what I know about it, they are pretty diffuse connections, pretty broad branching of neurons throughout the retina, or not throughout the whole retina, but probably not well-suited to manipulating fine spatial detail, but could very well be suited to incorporating some kind of circadian influence to the retina itself, or something else that you want the same signal to be broadly available throughout the retina.

Andrew Huberman: I'd like to take a quick break and acknowledge our sponsor, Helix Sleep. Helix Sleep makes mattresses and pillows that are customized to your unique sleep needs. Now, I've spoken many times before on this podcast about the fact that getting a great night's sleep is the foundation of mental health, physical health, and performance. When we aren't doing that on a consistent basis, everything suffers, and when we are sleeping well and enough, our mental health, our physical health, and our performance in all endeavors improves markedly.

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Andrew Huberman: I want to talk a little bit about physical spaces.

Jennifer Groh: Yeah.

Andrew Huberman: Recently, I was in New York, and someone took me to Grand Central, where there are these incredible arches in one of the hallways there.

Jennifer Groh: Mm-hmm.

Andrew Huberman: People should check this out. It's really, really cool.

Jennifer Groh: It is beautiful.

Andrew Huberman: It's beautiful. I mean, you have this high-ceiling, main kind of chamber room of Grand Central.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And there's also a hallway off to one side where you can go into a corner.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Do you know about this? And you can face into the corner, like you are going to...

Jennifer Groh: Uh-huh.

Andrew Huberman: Like you're facing the corner in shame, but you're not, and whoever you're with can go to the opposite diagonal corner.

Jennifer Groh: Oh, yeah, yeah.

Andrew Huberman: The ceiling is shaped like a somewhat of a dome.

Jennifer Groh: Uh-huh.

Andrew Huberman: It's contoured, but it's more or less a small dome.

Jennifer Groh: Right.

Andrew Huberman: But you are easily 25 feet away from this person that you're there with.

Jennifer Groh: Yep.

Andrew Huberman: Again, diagonal corner, and if you speak at a very, very low volume, they can hear you on the opposite side.

Jennifer Groh: Yeah, yeah.

Andrew Huberman: And if they speak, you can hear them, and what's wild is there's a lot of noise in the environment. This is Grand Central Station.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah, yeah.

Andrew Huberman: And we played with this a little bit. Like, if high-frequency sounds do seem to travel a little bit better in this environment, because if one person laughs, you can hear it very clearly.

Jennifer Groh: Okay.

Jennifer Groh: In that particular setting. Yeah.

Jennifer Groh: Uh-huh.

Andrew Huberman: But you can whisper, and they'll hear you, and they're 25 feet away in a major city with a ton of city noise.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: And so obviously, the sound waves are traveling along the ceiling.

Jennifer Groh: On that parabola. Yeah.

Andrew Huberman: And, it's a... You know, no pun intended, it's a mind bend to experience sound coming from a distance far away, not through a device, that is clearly being spoken at a low level, like a whisper, but you can hear it.

Jennifer Groh: Yeah.

Andrew Huberman: In the same way that it always weirds me out when I'm in San Diego in the winter, and the days are short, but it's, like, 80 degrees. Like, when days are short, it's supposed to be colder.

Jennifer Groh: Yes.

Andrew Huberman: Love San Diego.

Jennifer Groh: Yes.

Andrew Huberman: Great tacos, great people, but they're always talking about tacos down there. But it's so strange to be in a short day where it's hot.

Jennifer Groh: Yes.

Andrew Huberman: Because even if I go visit my relatives in Argentina, who experience Christmas in the summer, the days are long, and it's hot. And it's Christmas, and Santa Claus is supposed to be on a sleigh in the snow, but that's a whole different thing.

Jennifer Groh: Okay, yeah.

Andrew Huberman: But there's something about the way our nervous system is mapped, where we expect soft sounds to not travel very far.

Jennifer Groh: Sure. Sure.

Andrew Huberman: The opposite would be, like, shouting, and your voice just disappears even though the person's right in front of you.

Jennifer Groh: Right.

Andrew Huberman: It is so weird, and I feel like people should experience this naturally occurring experiment.

Jennifer Groh: Yeah, yeah.

Andrew Huberman: Because you walk away from that understanding sound intensity and frequency and localization completely differently.

Jennifer Groh: Uh-huh.

Jennifer Groh: Uh-huh.

Andrew Huberman: It changed the way I think about this, and it has nothing to do with being a neuroscientist. Like, that's crazy.

Jennifer Groh: Yeah.

Andrew Huberman: I can hear a whisper from 25 feet away, and I wondered, "Is this what it's like to be a wolf?" That would be really cool. It would also be really irritating, because you don't want to hear all the things that people are saying all the time.

Jennifer Groh: Right.

Jennifer Groh: Right, I mean, this is one of the problems with hearing aids. They amplify everything.

Andrew Huberman: Mm-hmm.

Jennifer Groh: It's not replacing what your brain does. It's not replacing what your ear normally does.

Andrew Huberman: Yeah. It's such a mind bend.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And it's so cool, and it-- Provided you're in New York, it costs nothing to do it.

Jennifer Groh: Mm-hmm.

Andrew Huberman: It's just that you just have to wait your turn. People are catching on to this or it's been known for a while. I'd like to get your thoughts on the opposite example, where if you go into, like a high-ceiling cathedral church.

Jennifer Groh: Yeah.

Andrew Huberman: What do high ceilings do for our perception of sound, given that there's a lot of space for the sound to travel?

Jennifer Groh: I'm not sure that I can add something that's really specific to that particular circumstance, but to say more generally that the sounds that we experience in a particular setting are really the combination of all of the reflective surfaces that are in that setting. And so, if you have a carpeted room, that's going to absorb sound on the floor, and so it's going to take out one part of what you would be hearing in a room that is not carpeted.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And the high ceilings, I would imagine that would kind of depend on what the surfaces are on the ceiling. One thing that'll happen in that kind of setting is that the sounds that go up that way, if it's a hard surface, they'll probably bounce off and come back down, but with a long delay. And once the delays get pretty long, then you do start to hear it as a whole separate sound.

Andrew Huberman: Almost like an echo.

Jennifer Groh: Not even almost like an echo, but actually an echo.

Andrew Huberman: Do you think this is used to amplify aspects of the music?

Jennifer Groh: Yeah, maybe that's why some of the older genres of music can be a little slower. A lot more-

Andrew Huberman: Like Gregorian chants?

Jennifer Groh: Yeah, longer sustained notes, because you don't want to have too many transitions from one note to the next.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Gregorian chant is a wonderful example of really kind of long, slow, sustained, many different voices blending together, versus a much faster, like Mozart, minuet or something like that.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Like, those notes would just jumble together with the kind of delay that we're talking about.

Andrew Huberman: Yeah, I mean, I think that the ability to localize sound, we talked about. We talked about quality of sound based on high and low frequency.

Jennifer Groh: Yeah.

Andrew Huberman: And I confess, I'm a little fixated on this idea that when people join together in sound, that you're communicating something very... That's the most effective way to communicate a feeling. And people will say, "Well, of course, you go to a concert, and you feel something," but in a concert, right, you have the performers, but the audience is often singing with them.

Jennifer Groh: Yeah.

Jennifer Groh: Right. I know, which is one of the most wonderful things.

Andrew Huberman: I recently wondered if... I was trying to think back to the '90s, and what created effective movements, and I thought, maybe what we need in America right now is we need, like, music that actually brings people together.

Jennifer Groh: Uh-huh.

Jennifer Groh: Yeah, yeah.

Andrew Huberman: Sounds really corny, but I really believe this.

Jennifer Groh: No, I do think that would be helpful.

Andrew Huberman: Maybe there are just too many different musical tastes now.

Jennifer Groh: So we should start by telling people, "You can't have that taste."

Andrew Huberman: Well, or there should be a new one, right?

Jennifer Groh: Yeah.

Andrew Huberman: And maybe it should be very primitive.

Jennifer Groh: Mm-hmm.

Andrew Huberman: I mean, the haka thing that we talked about earlier is a kind... it's an angry intention.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Right?

Jennifer Groh: Mm-hmm.

Andrew Huberman: And this is, I guess, where people will think... Like, my East Coast relatives would be like, "Oh, so you want us all to kumbaya?"

Jennifer Groh: Mm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: I have relatives from Jersey, so they're like, "I know out there in California, you're all kumbaya." But I think that the... We're sort of half-joking here.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: So, given the links between the emotion system and sound, and joining in sound... I mean, maybe this isn't too crazy an idea.

Jennifer Groh: Yeah.

Andrew Huberman: Maybe it's crazy, but who cares?

Jennifer Groh: Yeah.

Jennifer Groh: We have some advantages in science, that we have a comfort with argumentation, you know, with disagreeing about things, but agreeing fundamentally that we're going to go where the facts lead us. Do you know what I mean? So the disagreement is about what the facts are, but we agree that if we can come to agreement about facts, then we can proceed from there.

Jennifer Groh: But there's a feeling, and I have come to appreciate maybe isn't present in other domains, other kind of, you know, academic domains or areas of the occupations that people have, that may be a little different from what we have in science.

Jennifer Groh: You know, and I don't want to make science seem all perfect in all regards, but I think there's a sense of like, "Well, you may not want to hear that I think you're wrong, but we know those kinds of things have to be said."

Andrew Huberman: Mm-hmm.

Jennifer Groh: That you're going to have to defend your work in a peer review. When you try to get your work published, you're going to have to deal with peer review comments that you may not... You know, I certainly have had my moments where I've been like, "I cannot believe somebody thought that when I wrote this." You know what I mean?

Andrew Huberman: Mm.

Jennifer Groh: You know, but you go through that emotional period of time, and you're like, "Oh, well, actually, it's kind of... I can see how it's actually my fault for how I wrote it," you know? That it didn't actually say what I wanted, or it didn't set up the reader to understand the point I was making, so I need to fix this.

Jennifer Groh: And yes, you're right that there is a hole in the data here, that it doesn't fully support the hypothesis the way I thought it did, and that's okay. Like, it's okay not to have the story complete. It's okay not to have every detail of it right. Just acknowledge that you don't... You know, acknowledge what you think the weaknesses are.

Jennifer Groh: And I kind of don't see people acknowledging weakness in, let's say, the political domain right now.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Like, to acknowledge, "Well, you know, I'd like such and such a thing, but I can see that there's a counterargument to that. How can I address that, or should I change my mind?"

Andrew Huberman: Yeah, I think in science, we have agreements on how to evaluate strength of evidence.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And, like, we can't just have one data point and draw a conclusion from that. We won't convince anyone, even if we're convinced, and if we should check ourselves.

Jennifer Groh: Right.

Jennifer Groh: Right, right.

Andrew Huberman: I do have a question about the auditory system again, which is, a number of people, including myself, are obsessed with trying to find what is the optimal thing to listen to, perhaps it's nothing in order to be able to focus.

Jennifer Groh: Yes.

Jennifer Groh: Mm, mm-hmm.

Jennifer Groh: Mm.

Andrew Huberman: And the data, as I see them, are basically pointing to silence... is best.

Jennifer Groh: Yeah.

Andrew Huberman: And so I have a question about silence, and the voice in our head.

Jennifer Groh: Yeah.

Jennifer Groh: Uh-huh.

Andrew Huberman: I have a question about that.

Jennifer Groh: Yeah.

Andrew Huberman: But also, it's very clear, based on what we've discussed up until now, that certain frequencies of sound actually play a role in our emotion and cognition. I will sometimes listen to white noise. There are a number of companies now that put out free content of it's not necessarily binaural beats, but different frequencies that oscillate.

Jennifer Groh: Right.

Andrew Huberman: It could be totally placebo, but I don't think so, because they reference a number of studies.

Jennifer Groh: Right.

Andrew Huberman: It looks like you can get some cognitive enhancement or focus enhancement.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And I use these. There's some great, you know, study-with-me channels online, where you sit there, and you work while they work. What are your thoughts on the use of sound as a way to change brain state?

Jennifer Groh: Okay, so I want to back up on this question because I think you're asking a pretty deep question. One might wonder, why would that matter? Like, what is actually going on in our brain that that kind of pairing would have an effect, regardless of what might turn out to be sort of the best option?

Andrew Huberman: Mm-hmm.

Jennifer Groh: And so, one theory that I like to think about a lot is the theory of thought, and what is actually going on in our brains when we think.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And this theory is that what goes on in our brains when we think might be that we're running simulations related to the thought, using that sensory motor infrastructure of the brain.

Andrew Huberman: Could you elaborate?

Jennifer Groh: So the theory is that, like, maybe when you think about a cat, for example, or you think the concept of a cat, that the mental instantiation of that or the brain mechanism instantiation of having that thought is to run a little simulation, and visual cortex that kind of includes what a cat looks like, a simulation and auditory cortex, that what does a cat sound like? And as I'm telling you this, I've used the word cat. What color cat are you thinking?

Andrew Huberman: I'm thinking of a gray cat, but I keep smelling kitty litter.

Jennifer Groh: Okay.

Andrew Huberman: Because my sister had cats, and it drove me... The smell of kitty litter is just so aversive to me.

Jennifer Groh: Right. And so you had no hesitation in telling me the color and adding an additional sensory quality.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So it's a bit of a just-so story, but I think that it's a plausible possibility that that's, in fact, what's happening when we think. And some of what kind of tangentially supports this is that we have many more sensory areas of the brain than monkeys do, than more distant mammalian relatives do.

Jennifer Groh: As if what might have happened to allow us to become so smart is to, you know, make extra copies of some of these sensory areas of the brain. And then when you have an extra copy, you're no longer so constrained, right? We don't really see or hear any better than monkeys do. So what's this extra tissue doing for us? Possibility is that we're using it to generate these simulations, and that running these simulations is kind of what thought is.

Andrew Huberman: Interesting. Is it helpful? Is it adaptive?

Jennifer Groh: Well, it might just be the only game in town. It provides an explanation for why you might be driving on the freeway and having to merge into difficult traffic, and telling your passenger, "Okay, be quiet. I've got to pay attention now."

Andrew Huberman: Hmm.

Jennifer Groh: Why would speech impair you from visual motor, if it wasn't all part of a kind of cognitive system that's in operation?

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And maybe you need to shift some resources away from processing the conversation and towards some... You know, actually dealing with the here and now sensory motor task.

Andrew Huberman: Mm.

Andrew Huberman: I like this a lot, and I want to continue down this thread because we've never talked about what thought is on this podcast.

Jennifer Groh: Yeah.

Andrew Huberman: And I've wondered, like, why is it that so many of our thoughts are incomplete sentences, they're so fractured?

Jennifer Groh: Mm-hmm.

Andrew Huberman: And if you really just track your thoughts for a moment, you realize they jump around even if they're around some coherent framework or subject.

Jennifer Groh: Yeah.

Jennifer Groh: Mm-hmm. It's predictable. Like, you can see the train of thought sometimes. Like, they rarely jump completely in some totally new-

Andrew Huberman: Sorry, I'm laughing. For some people, they really do.

Jennifer Groh: Do they really?

Andrew Huberman: They do.

Jennifer Groh: Okay.

Andrew Huberman: They do. Sort of like the liminal state between awake and sleep.

Jennifer Groh: Uh-huh.

Andrew Huberman: I like to lie there right as I'm waking up, and try and stay on a thought thread.

Jennifer Groh: Yeah.

Jennifer Groh: And things just-

Jennifer Groh: Yeah.

Andrew Huberman: And then I'll just chuckle to myself 30 seconds later, it's someplace completely...

Jennifer Groh: Gone somewhere.

Andrew Huberman: Because in that liminal state, you're still in a pseudo-dream state.

Jennifer Groh: Yeah.

Jennifer Groh: One time in my class, one of my undergraduate classes, I asked people to try to without thinking too much, come up with a word that was totally and completely unrelated to anything that we had just been talking about.

Andrew Huberman: Ooh.

Jennifer Groh: I'm going to give you a moment, but not too long.

Andrew Huberman: Mm.

Jennifer Groh: Okay.

Andrew Huberman: It's really tough.

Jennifer Groh: Isn't it hard?

Andrew Huberman: The first word that leapt to mind was cacophony, and it's like, "No, that's directly in the framework of what we're talking about."

Jennifer Groh: It is, right, right.

Andrew Huberman: I'm like, "Damn it."

Jennifer Groh: Yeah.

Andrew Huberman: And then I looked at the paneling on the wall, and I thought maybe it's something about...

Jennifer Groh: And it's like.

Andrew Huberman: And like, now I could do it. Like, I'd say like lacquer or something like that.

Jennifer Groh: Right, yeah. But again, it's going to be related, right?

Andrew Huberman: Yeah.

Andrew Huberman: Yeah, it's really, really tough.

Jennifer Groh: And these are kids that probably have a 30,000-word vocabulary, right?

Andrew Huberman: Mm-hmm.

Jennifer Groh: That's a typical psy vocabulary.

Andrew Huberman: And young brains, so-

Jennifer Groh: Young brains. And I had, like, 15 students in the class.

Andrew Huberman: Yeah.

Andrew Huberman: Interesting.

Jennifer Groh: I think two of them came up with the word elephant, and three of them came up with the word banana. You know, they were clearly not random words.

Andrew Huberman: So I think we're talking about something extremely important now that I would like your thoughts on. Because this is really about how the brain works, right?

Jennifer Groh: Okay.

Jennifer Groh: Yeah.

Andrew Huberman: And I love the auditory system, and we'll get back to it, but it's part of this larger question of how our brains work.

Jennifer Groh: Yeah.

Andrew Huberman: I'm asking about binaural beats or white noise or pink noise or brown noise, in order to enhance focus. There's a lot of interest in that.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: But what we're really talking about is what our thoughts, how we think, and how to anchor our thinking and align it with action.

Jennifer Groh: Right.

Andrew Huberman: And so I'm obsessed with this notion of attractor states, and the way I think about this, tell me if I have this wrong, is I think about brain states as very context-dependent.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Especially nowadays, with the amount of information we're being bombarded with through our phones.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And because a walk from the car to your desk, or a walk from the car to your first meeting is a very different experience with a phone than it was, like, 20 years ago.

Jennifer Groh: Oh, totally.

Andrew Huberman: And people who are younger than me won't know what we're talking about. They're going to be like, "What are you talking about? You were always in communi..." No, that's not how it was.

Jennifer Groh: Right.

Andrew Huberman: But the way I think about the brain is that my thinking is more or less like a ball bearing on a flat surface.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And the more fatigued I am, the more unbalanced that surface is.

Jennifer Groh: Mm-hmm.

Andrew Huberman: But assuming I've slept well, and I'm hydrated, and caffeinated, and satisfied, I don't have some basic need, like having to go to the bathroom, or gnawing hunger, or need for a coffee.

Jennifer Groh: Mm-hmm.

Andrew Huberman: I'm like a ball bearing on a flat surface.

Jennifer Groh: Right.

Andrew Huberman: And that flat surface is relatively stable.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Now, as I move into something like a discussion on this podcast, or I'm reading something, the dimples start to form on that surface, and so that ball bearing can rest, but you can still nudge it out pretty easily.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Right.

Andrew Huberman: But that as I go further and further into an activity, it becomes a trench, and that ball bearing sinks to the bottom of that trench.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm. Mm-hmm.

Andrew Huberman: And Christof Koch, who was here recently, said, "The flow state that we all want so badly is where we actually forget about ourselves because we're so deeply in that state of doing." I think he's right, and I think that many people think that they have ADHD.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: Many people think that they can't concentrate.

Jennifer Groh: Yeah.

Andrew Huberman: I actually believe there are some people with clinically diagnosable ADHD, but that most people are just not allowing themselves a narrow enough set of sensory inputs and context to drop into that trench, and yet it's the thing that feels so good.

Jennifer Groh: Right.

Jennifer Groh: It does. It feels-

Andrew Huberman: When we're in it, and when we emerge from it, we're like, "Oh!" Like, that's what we're supposed to do.

Jennifer Groh: Yeah.

Andrew Huberman: And so what you described in the classroom, where your students can't even come up with a word unrelated to the conversation, is one of these attractor states.

Jennifer Groh: Yeah.

Andrew Huberman: Is that... I mean, where does that sit with you?

Jennifer Groh: Yeah, I think that sounds good to me, and I think I too share an interest in how to get myself into that flow state, and what to do when I have sort of bottomed out in, like, one particular...

Andrew Huberman: Mm-hmm.

Jennifer Groh: I might be in flow and making good progress on something, and then I get stuck, and I stop.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And I find that changing my immediate environment is a good way to get out of that little rut.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So for example, if I'm working on a difficult piece of writing, I might get to the end of what I can achieve in one particular cafe, but if I go to another cafe, you know?

Andrew Huberman: Mm-hmm.

Andrew Huberman: Now, this is a very smart strategy. Actually, a neuroscientist whose work I really admire, and I also really enjoy as a person, is Marla Feller at UC Berkeley.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And I think she was the one that told me that at scientific conferences, which can go on for two or three days, and sometimes the sessions are very long.

Jennifer Groh: Yeah.

Andrew Huberman: You have morning, afternoon, evening sessions. It's a lot.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Jennifer Groh: It's a lot.

Andrew Huberman: Lots to pay attention to, a lot of sitting. She would move seats around the auditorium because she swore that it...

Jennifer Groh: Uh-huh.

Jennifer Groh: I do that, too.

Andrew Huberman: I think it was Marla. Marla, if it wasn't you, forgive me. But I think it was Marla. She would move seats so that she could always anchor her attention for each talk or set of talks.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Not necessarily, you know, moving every moment, but every hour or so. I think this is absolutely right. And so, I wonder whether or not some of these effects of binaural beats or other frequencies improving focus, has to do with just needing to fill the auditory sensory space.

Jennifer Groh: Mm-hmm.

Jennifer Groh: That could be.

Andrew Huberman: Like, if I go... I work in my basement now. I've set up my basement as, like, the ideal work environment. No phones, no internet.

Jennifer Groh: Uh-huh.

Andrew Huberman: Don't allow it.

Jennifer Groh: Uh-huh.

Andrew Huberman: When I go down there, it's just me and my thoughts.

Jennifer Groh: Yeah. Yeah, yeah.

Andrew Huberman: I do allow some music, but when I get down there, the first 10, 15 minutes are excruciating. Like, you can hear every distracting thought. I can think of a million things that could just pop to mind.

Jennifer Groh: Yeah.

Andrew Huberman: But after about 10, 15 minutes, that all fades away, and I can work down there for hours. Like, no one can find me down there. I love it.

Jennifer Groh: Right.

Jennifer Groh: Yeah.

Andrew Huberman: I've had to create this physical space because nowadays, there's just so much infiltration through devices.

Jennifer Groh: Right.

Jennifer Groh: Right.

Andrew Huberman: So I wonder, for some people, they think they can't focus, but there's a sensory space that needs filling.

Jennifer Groh: Yeah, they maybe haven't figured out how they need to hack themselves.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And I think that one reason why I haven't specifically answered your question yet is because I think the answer may be specific to the individual. So for me, for music, I like to listen to music while I work, but I do it sometimes but not other times. But as a musician myself, the music can't be too interesting to me.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Like, it has to be either stuff I know really well already, so that it's not, like, grabbing my attention to actually listen to the song, or it should be classical music or something that doesn't have lyrics, so I don't have that language intrusion to my thoughts.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Sometimes I find it useful to make a playlist for a particular project, so that those songs start to become a cue for working on that project.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So I don't think there's going to be one answer that fits all circumstances, but to maybe have an understanding of what works for the particular person, the particular project.

Andrew Huberman: There's some very interesting data coming out of Mark D'Esposito's lab.

Jennifer Groh: Okay.

Andrew Huberman: We've had him on the podcast before about dementia and ways to improve working memory, which seems to be more of a dopamine thing.

Jennifer Groh: Okay. Uh-huh.

Andrew Huberman: But if you can augment acetylcholine, you can improve attention. It's just so clear that these four brain structures, like nucleus basalis, that are releasing acetylcholine, they're necessary but not sufficient to establish an attentional spotlight.

Andrew Huberman: The reason I was going to mention this context is, the cortex is rich with the nerve endings of these acetylcholine-releasing neurons.

Jennifer Groh: Mm-hmm.

Andrew Huberman: The colliculus has acetylcholine input, and it seems like any multisensory area of the brain, where you need to integrate vision and sound and context and thinking and all this stuff and intention and action, you have norepinephrine to raise overall alertness in the brain and body.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: That seems to be its general function. Dopamine does many different things in different areas, as you know, but it seems like acetylcholine is the thing that really creates this ability for attentional spotlighting, that being able to anchor one's thoughts and actions towards a specific set of sensory combinations.

Andrew Huberman: And so when we talk about listening to music, or not listening to music, or one particular space or another space that one works in, I think so much of it is trying to...

Jennifer Groh: Mm-hmm.

Andrew Huberman: You know, we're trying to create these spheres of attention that are very compact. And I don't think that people really appreciate just how hard that problem becomes when you take a device, I'm not anti-phones, and you're bringing in another sphere of, what, 25,000 different spheres of attention that you can scroll through?

Jennifer Groh: Mm-hmm.

Andrew Huberman: It makes perfect sense why we wouldn't be able to focus. Because acetylcholine is like a resource that we spend out, and it can be replenished in sleep.

Jennifer Groh: Mm-hmm. Mm-hmm.

Andrew Huberman: You said you'll hit a flow state or a focus state, and then we have to switch, yeah, or you hit a wall.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: I feel like it's a currency.

Jennifer Groh: Yeah.

Andrew Huberman: It's not something that we should be able to just use, you know, infinitum.

Jennifer Groh: Yeah.

Jennifer Groh: So, I think a theme of some of your podcast episodes involves, you know, physical exercise and workouts, and what's the best routine for this, that, or the other aspect of the workout.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And generally, interval training, I think, comes up as a pretty effective strategy.

Andrew Huberman: Mm-hmm, mm-hmm.

Jennifer Groh: I sometimes think about that in the context of more mental work, because I have not had good luck screening out all the distractions to get going on deep writing.

Andrew Huberman: Mm-hmm.

Jennifer Groh: For me, it's more like I can push out a sentence, and that's so effortful that then I need to take a break.

Andrew Huberman: Oh, well, I feel much better now because... Well, I think this is where you're going. You may find comfort in the fact that we've had some just phenomenal physical coaches on here. I mean, people who are degreed in physiology, and teach super high-level athletes.

Jennifer Groh: Yeah.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And more than one of them has said that the attention span of the athlete, in terms of ability to focus on cognitive information, tutorial, and learning, even conversation, directly maps onto the duration of their event.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Like, the sprinters can pay attention for about the duration of their sprint.

Jennifer Groh: About 10 seconds? Okay.

Andrew Huberman: Yeah. Well, for the 100-meter, right?

Jennifer Groh: Yeah.

Andrew Huberman: But they can repeat that because the sprinter will sprint, and then walk, and then repeat, right?

Jennifer Groh: Uh-huh. Yeah.

Jennifer Groh: And then sprint again.

Jennifer Groh: Exactly.

Andrew Huberman: So it's a training.

Jennifer Groh: So it's like I'll write a sentence, then I'll check one news site, then I'll write another sentence, and I'll check another news site.

Andrew Huberman: Love it.

Jennifer Groh: And if I try to just write one sentence and then another sentence, and then another sentence, I get frustrated with myself. It seems like it's... I don't know. I can't necessarily do it. Sometimes I can, but I've let go of working efficiently as a goal in and of itself.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Was it always the case, or do you think the advent of phones has made it such that you have this sort of step function?

Jennifer Groh: No, I've always had a problem with the internet. The phone is just the way in.

Andrew Huberman: Yeah.

Jennifer Groh: But the phone actually can be helpful to me, because I can close all the tabs on my laptop, and just have my phone be the way that I access the internet, for example.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And that allows for a kind of a mental and physical separation, where I can kind of be like, "Okay, now I'm doing this. Okay, now I'm doing that," and keep them kind of separated.

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Andrew Huberman: I love that you're sharing this. Many people will find comfort in hearing that. You know, my podcast producer, Rob Moore, he's done multiple triathlons, and he's an endurance guy. At one point in his past, he had carried a lot more muscle. He's still very fit and strong, but he shifted over to endurance events. And this guy can work like nobody's business.

Jennifer Groh: Mm-hmm.

Andrew Huberman: He can work for hours and hours and hours and hours.

Jennifer Groh: Yeah.

Andrew Huberman: And I feel like that's how I was in graduate school and as a postdoc.

Jennifer Groh: Yeah.

Andrew Huberman: And I suppose I'm more of an endurance athlete with my mental work.

Jennifer Groh: Yeah.

Andrew Huberman: I think maybe we should start thinking about cognition in these terms.

Jennifer Groh: Yeah.

Andrew Huberman: Because after all, we're not just two people talking about work habits. You're a neuroscientist, and you study sensory integration and brain states, and I still consider myself a neuroscientist even though I haven't gotten my hands dirty in the lab in a while.

Jennifer Groh: Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: I think this is very important because I think people flagellate themselves over the fact that they couldn't pay attention to write one paragraph. And they think that therefore that means they shouldn't write or that they can't write more than one paragraph, but it sounds like they need to create a system.

Jennifer Groh: I come out of the little mini internet break knowing what the next sentence needs to say.

Andrew Huberman: Interesting. So, you're really like an interval athlete when it comes to mental work.

Jennifer Groh: With the hard stuff. With the easy stuff, I can just, you know, do it, right?

Andrew Huberman: Very interesting.

Jennifer Groh: But it's this sense of effortful cognition that takes its own time, and it just takes its time.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And I don't control that. I do try to set myself up to allow the mental work to happen when I'm in the shower or in the car or whatever. So, for example, if I'm going to work on a grant application with somebody, and we're sharing, you know, the writing, and I know I can't start until I've had a conversation with the collaborator about who's doing what, and what we think this grant is going to be about, I might set up that meeting when there's going to be downtime afterwards.

Jennifer Groh: I did this just yesterday, where I had a meeting yesterday morning, knowing that then I was going to be on an airplane for quite a while, knowing that without my having to do anything about it, the ideas are going to marinate.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Stuff is going to be happening that I'm not aware of, and that when I come out of that, I'll probably know what I want at least the first couple of sentences to say.

Andrew Huberman: Yeah, you trust the sort of process of brain state shifting back and forth.

Jennifer Groh: Mm-hmm.

Andrew Huberman: You don't fight it. You trust it.

Jennifer Groh: Yeah, I have to. I mean, I don't see any other way to do it.

Andrew Huberman: Mm-hmm.

Jennifer Groh: But I think it's a little like, you know, you need rest and recovery for physical exercise, and honestly, it's not like the brain and muscles are all that different from each other, right?

Andrew Huberman: Mm-hmm.

Andrew Huberman: Well, I always think of all nerve action as motor, and we could talk about that. I mean, Sherrington said, right? The final common path. The Nobel Prize winner, Sherrington.

Jennifer Groh: Yeah.

Andrew Huberman: The final common path is movement. I mean, that's what we evolved to do first, and thinking is a form of movement.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: It is hard for people to grasp sometimes.

Jennifer Groh: Right.

Andrew Huberman: And people perhaps can grasp it more easily in the context of song. Certain songs sound like they're moving forward.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Like, it feels like a physical progression. They make you want to move.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Right? They actually inspire movement. Actually, there are very few sounds that inspire stillness. They tend to be the slow, oscillatory sounds, ocean waves, things that don't have a structure.

Jennifer Groh: Right.

Andrew Huberman: They're very fractal, to the point where you don't see that fractal structure.

Jennifer Groh: Mm-hmm.

Andrew Huberman: It just kind of breaks up, and then your mind just goes into drift. The only other person I've ever met who has described embracing their mental process the same way that you have is my good friend in the... You know, he's this world-renowned producer, Rick Rubin. He just trusts that there are certain times of day when things are going to come to him, that certain things aren't ready, and they just need to marinate in sleep or in dreams.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And he doesn't even really try and assign it to sleep and dreams.

Jennifer Groh: Yep.

Andrew Huberman: He just understands the process. It eventually is going to emerge. He's not like, "Why can't I get this thing out?" And so, he's very much in flow with his own, you know, peaks and valleys and attention.

Jennifer Groh: Being blocked can mean you don't know yet what needs to come next.

Andrew Huberman: Mm-hmm. Yeah, so important for people to hear because I think most everyone is trying to drop into that deep trench attractor state as quickly as possible.

Jennifer Groh: Right.

Andrew Huberman: And yet, there are ways that we can do that, and maybe we can talk about that for a few moments. I'd be remiss if I didn't ask about your experience as a musician. What instrument do you play?

Jennifer Groh: Mm-hmm.

Jennifer Groh: Well, I started off with flute, you know, starting in fifth grade.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Now, I play the banjo, and I sing.

Andrew Huberman: Nice. When you're doing that, do you find that your attention is anchored for the duration of the performance or practice?

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yes, especially when performing. There's a certain... Like, I feel that the singing, in particular, can come out better in performance than it does in practice.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Not always, unfortunately. The more technically challenging playing of the banjo is a little hard. You know, the adrenaline helps with the singing and hurts with the banjo, let's put it that way.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Interesting.

Jennifer Groh: Yeah.

Andrew Huberman: Because adrenaline... What, it's like this inverted U-shaped thing?

Jennifer Groh: Yeah.

Andrew Huberman: Like, at very low levels, we can't focus, at higher levels, we can focus, and if it gets too high, we're discombobulated.

Jennifer Groh: Right.

Andrew Huberman: Yeah.

Jennifer Groh: I mean, it's just the shaking of the fingers that can be problematic.

Andrew Huberman: Mm.

Jennifer Groh: But the other problem is, you know, from an attention music performance standpoint, I would much prefer to sing a given song only once in a rehearsal than to go over it more than once, because I can't remember the words the second time through.

Andrew Huberman: Interesting.

Jennifer Groh: And I think it's this mental checklist of, "Did I already sing that? I remember singing that. But no, wait a second, but now I have to sing it again?" You know, and just kind of keeping track of where I'm at gets harder the second time through.

Andrew Huberman: Pressure is an interesting thing to explore in this context of brain states, because it sounds like you've embraced this kind of oscillatory flow of your attention. Like, in one context, it works this way, and you're not pressuring yourself to do something. There was a really interesting paper recently about the neural basis of choking.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And not physically choking, but when something really critical is on the line, what happens?

Jennifer Groh: Yeah.

Andrew Huberman: Did you see that paper? I thought it was...

Jennifer Groh: I have not, but like...

Andrew Huberman: Okay.

Jennifer Groh: Yeah.

Andrew Huberman: It's really cool. They record from motor cortex and a bunch of other areas, but the basic finding is that, if there's the potential for a low payoff if you get something right...

Jennifer Groh: Uh-huh.

Andrew Huberman: Well, let's just say it's like throwing darts, which the analogous experiment would be like throwing darts.

Jennifer Groh: Yeah.

Andrew Huberman: You say, well, let's say if you get on the dartboard, you get a dollar.

Jennifer Groh: Right.

Andrew Huberman: If you get within a certain distance of the bullseye, you get, I don't know, 1,000 dollars. Pretty good. If you bullseye, you get 10 million dollars. What ends up happening is that the performance on the high-stakes condition is always worse, but just in terms of just even the basic mechanics.

Jennifer Groh: Yeah.

Andrew Huberman: And so choking turns out to be a recruitment of too many motor units.

Jennifer Groh: Yeah.

Andrew Huberman: You basically overinvest motor effort as opposed to staying chill and staying in the zone.

Jennifer Groh: Mm-hmm. Try too hard.

Andrew Huberman: Where, you still might not bullseye. This wasn't the exact experiment, but again, it's analogous to what they really did. But you stand a much greater chance if you stay within your ability... You already know how to do this thing. And subjects choke when the stakes go way up because they just overinvest too much motor activity.

Jennifer Groh: Yeah.

Jennifer Groh: Perfectionism.

Andrew Huberman: Yep.

Jennifer Groh: It's a trap.

Andrew Huberman: You have to almost mentally convince yourself that the stakes are lower, but you can't really lie to yourself. Anyway, it's pretty interesting. It's pretty interesting. I love that we're talking about brain states and sensory inputs. In this case, it's knowledge about potential outcomes. I want to talk about chickens.

Jennifer Groh: Yes.

Andrew Huberman: You have chickens.

Jennifer Groh: I do.

Andrew Huberman: And so, first, I'll ask you about chickens and what you find so interesting about them, and then I want your thoughts about a really wild, wild finding about chickens and vision and attention, that anyone who's ever raised chickens on a farm probably knows, but only a couple of neuroscientists know.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Okay.

Andrew Huberman: You'll probably know it, but anyway. What kind of chickens do you have?

Jennifer Groh: I have Bantam Mille Fleurs.

Andrew Huberman: So, Bantam means little guys?

Jennifer Groh: They're little guys. Yep.

Andrew Huberman: Mille Fleurs.

Jennifer Groh: Mille Fleur. It's...

Andrew Huberman: How big are the eggs?

Jennifer Groh: They're half the size of a standard grade A large egg from the supermarket.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Are they tasty?

Jennifer Groh: Very tasty.

Andrew Huberman: Okay, how many does it take to make a decent-sized omelet?

Jennifer Groh: Well, double the number that you would normally put in, and that would be-

Andrew Huberman: Okay, so for me, it would be, like, eight.

Jennifer Groh: Yeah.

Andrew Huberman: Okay. So, when did you start raising chickens?

Jennifer Groh: Yeah.

Jennifer Groh: So, I had Bantams when I was a kid. I live in Chapel Hill, and around 2012 or so, maybe 2011, the town changed its zoning laws to allow chickens in the kind of neighborhood that I live in. So I'm like, "Okay, this is what we're going to do."

Andrew Huberman: Mm-hmm.

Jennifer Groh: My husband's allergic to dogs and cats and anything with fur, so, you know, chickens were kind of the option. I suppose we could have gotten rabbits and kept them outside.

Andrew Huberman: Or a hairless cat.

Jennifer Groh: You know, I won't say that we didn't have that discussion but it didn't go anywhere.

Andrew Huberman: Sorry.

Andrew Huberman: They're pretty funny.

Jennifer Groh: You know, you're committing...

Andrew Huberman: I got a friend with one. They're sweet. They're like little monkeys. They're always crawling up people. Yeah.

Jennifer Groh: Well, they really... I have met a hairless cat, and I do think that they have lovely personalities, you know, extrapolating from this N of one. You know, because they don't look so great, so they can't get by on their looks.

Andrew Huberman: Oh, my goodness. This is funny.

Jennifer Groh: Oh, dear.

Andrew Huberman: No, no, no, no. I totally buy it.

Jennifer Groh: Yeah.

Andrew Huberman: Yeah.

Jennifer Groh: So they're a very pleasant personality, I think. And the warmth of them, because you really feel the warmth of their skin.

Andrew Huberman: Mm-hmm.

Jennifer Groh: But anyway, so chickens it was, and is, and I like the Bantams because they really have a lot of personality.

Andrew Huberman: Mm-hmm.

Jennifer Groh: You know, they haven't been bred to be egg layers. They've been bred to be pets.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And so, they have a certain pleasing personality and interest in interacting with people that I think might be different from standard kind of farm chickens.

Andrew Huberman: Well, I have a non-invasive experiment for you to try.

Jennifer Groh: Okay.

Andrew Huberman: Some years ago, I got very interested in the relationship between vision and brain states.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And there's some interesting literature about the fact that when we view horizons, especially from a vista, that it relaxes our autonomic nervous system. We go into a more parasympathetic mode.

Jennifer Groh: Okay. Mm-hmm.

Andrew Huberman: And it turns out when we view horizons, our eyes naturally go into panoramic vision. We're not foveating to one...

Jennifer Groh: Mm-hmm.

Andrew Huberman: That's nerd speak, by the way. Neuroscience nerd speak. We're not focusing on one particular point.

Jennifer Groh: Right.

Andrew Huberman: If you track one particular point, you obviously do a smooth pursuit of that point with your eyes.

Jennifer Groh: Mm-hmm.

Andrew Huberman: But then you just go to a vista, you look at a horizon, your eyes naturally just dilate as we say, right?

Jennifer Groh: Mm-hmm.

Andrew Huberman: But it's panoramic vision. Whereas when we do a vergence eye movement, bring our eyes together at a particular point, there's this really interesting increase in the output of areas like locus coeruleus that are involved in attention, norepinephrine.

Jennifer Groh: Mm-hmm.

Andrew Huberman: I thought, "This is really wild."

Andrew Huberman: And I was interested in respiration and brain states, and I was like, "Oh, cool, like, maybe we're just staring into little boxes too much, and that's why we feel so attentionally exhausted and depleted."

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: Makes sense. Attention's a resource. Okay, I think there's some evidence now to support every one of those statements, although we need more brain recordings from humans to really get to the nitty-gritty.

Andrew Huberman: But then my graduate advisor, who unfortunately has passed away, had told me some time ago, she said, "You know, you can hypnotize chickens." And I said, "Really?" Because that's a lyric in an Iggy Pop song, "I'm hypnotizing chickens," and I thought, "Wait, what?" And she said, "Yeah, you can hypnotize chickens, but they're not really hypnotized. They're just hyper-focused."

Andrew Huberman: And I was like, "Isn't that what hypnosis is?" And she's like, "Yeah, I guess. I always thought hypnosis was like a dream." Hypnosis is a state of hyper-focus. I have a colleague who does clinical hypnosis, David Spiegel. It's approved by the American Psychiatric Association. Hyper-focus. Here's what you do, and you can find this. People who grew up on farms do this. And there are videos of this on YouTube.

Andrew Huberman: They take a chicken, and they'll hold the chicken, and they'll draw a line in the dirt, and they'll place the chicken's beak on the line, and the chicken will just stay there for many, many, many minutes. You actually have to pick them up and kind of get them to orient to the rest of their visual field. Turns out that any birds that eat off the ground have a very complex, like, sensory motor challenge that my colleague, the late...

Jennifer Groh: Uh-huh.

Andrew Huberman: He died of old age. So, Harvey Karten told me about, which is, you know, they got this tiny beak, and a seed is small, and they...

Jennifer Groh: Yeah.

Andrew Huberman: You know, you and I could pick up things off a table pretty quickly.

Jennifer Groh: Uh-huh.

Andrew Huberman: But they're doing this with this tiny beak, but their eyes are on the side of their head.

Jennifer Groh: Yeah.

Andrew Huberman: So in order to do that, as their head descends really fast, in order to not smash their beak into the surface, and make an accurate pickup of the seed or whatever it is, or bug, their eyes undergo a vergence eye movement.

Jennifer Groh: Right.

Jennifer Groh: Yeah.

Andrew Huberman: They shift their eyes inward and they get a little cone of attention.

Jennifer Groh: Uh-huh.

Jennifer Groh: A little cone of attention.

Andrew Huberman: So when you draw a line and you focus them down, they're literally stuck in that cone of attention.

Jennifer Groh: Staring at that...

Andrew Huberman: And then, I started looking at the literature on behavioral treatments for ADHD, or just for attention, and not in this country, but in China, many schoolroom classrooms begin before the lesson with the kids literally focusing on a single spot.

Jennifer Groh: Yeah.

Andrew Huberman: Which seems a little bit, like, kind of military. But they have embraced this relationship between visual attention and overall kind of ability to cognitively focus.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And chickens do it, kids in China are doing it, and it actually has been shown to work pretty well for improving attention in the subsequent, you know, 40 minutes to an hour.

Jennifer Groh: That's really interesting.

Andrew Huberman: So, our attention tends to follow our vision, not necessarily the other way around.

Jennifer Groh: So, I've seen some of these chicken YouTube videos, but I haven't dug into it yet to try it with my own chickens, but now you're motivating me to try it.

Andrew Huberman: Yeah, let me know what you find.

Jennifer Groh: As far as you know, is the drawing of the line an important part of this?

Andrew Huberman: Yeah, it is.

Jennifer Groh: You can't just put a line down and then bring the chicken over?

Andrew Huberman: Yeah, so I have to look at these videos again. It's been a little while, but what they do is they place the chicken kind of beak facing down, but they're not pushing the bird down, and then they draw the line-

Jennifer Groh: Beak down.

Jennifer Groh: Starting from the beak?

Andrew Huberman: Starting... No, starting... I can't remember if it's starting from the beak outward or outward toward the beak.

Jennifer Groh: Okay.

Andrew Huberman: But what it does is it... Harvey was the one... Okay, Harvey, the late, great Harvey Karten, I should just mention, he's...

Jennifer Groh: Harvey Karten.

Andrew Huberman: I'll put a link to an obit I wrote.

Jennifer Groh: He was great.

Andrew Huberman: He was one of history's and the world's most incredible comparative neuroscientists.

Jennifer Groh: Yeah.

Andrew Huberman: He also was a fire hose of information. He used to walk into my lab, and just start talking about diving birds and...

Jennifer Groh: Mm-hmm.

Andrew Huberman: Yeah, he was one of those.

Jennifer Groh: Mm-hmm.

Andrew Huberman: But he made me seem quiet. And he explained that when the birds, which have eyes on the side of their head, do this vergence eye movement, they get locked there.

Jennifer Groh: Yeah.

Jennifer Groh: So, maybe it has to be away from the beak towards the beak?

Andrew Huberman: Probably. Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: And it's funny because I mentioned this a few places before I had a podcast, and people who grew up on farms were like: "Oh, yeah, we would do that."

Jennifer Groh: Oh, interesting.

Andrew Huberman: You can actually then take the bird and flip it over.

Jennifer Groh: Yeah.

Andrew Huberman: Aggressive roosters become very calm, or you can work with them, manageable.

Jennifer Groh: Wow!

Andrew Huberman: And so, the vision drives our brain states.

Jennifer Groh: Yeah.

Andrew Huberman: And I think about this a lot in the context of the phone where our vision is brought into this little box.

Jennifer Groh: Sure.

Andrew Huberman: But the number of different contexts within that box is infinite.

Jennifer Groh: Yeah.

Jennifer Groh: I mean, do you find... I mean, diving into the phone thing, I'm definitely going to try the chicken thing.

Andrew Huberman: Yeah, let me know.

Jennifer Groh: Yeah. Maybe I'll make a video.

Andrew Huberman: I mean, blinders, like they put on horses.

Jennifer Groh: Yeah. To keep them focused.

Andrew Huberman: Or they put on... Yeah.

Jennifer Groh: Yeah.

Andrew Huberman: Falconers use these, right? The idea is you're trying to literally-

Jennifer Groh: Mm-hmm. Yeah.

Jennifer Groh: To physically make you focus on one thing.

Andrew Huberman: That's right.

Jennifer Groh: Yeah.

Andrew Huberman: And there are some funny pictures that you can find on X every once in a while of focusing tools from the 1930s, where they would literally put kids in these helmets with just two little eye portals, and it was supposed to keep the kids that couldn't pay attention focused on their work so they wouldn't see any other kids.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Andrew Huberman: We think about it, it seems so silly and so barbaric.

Jennifer Groh: Yeah.

Jennifer Groh: Well, I think, too, it could be helpful to ponder why one's attention is being drawn to other things. Because I think that, like, the most relaxed I can get these days is if I know someone else is monitoring the state of the world and will let me know if there's some major disaster.

Andrew Huberman: I've had to do some of that outsourcing, too.

Jennifer Groh: Right?

Andrew Huberman: Yeah.

Jennifer Groh: But having that outsourced is super helpful because it satisfies the need to have a warning system going on at all times.

Andrew Huberman: Yeah.

Andrew Huberman: Mm-hmm.

Jennifer Groh: And it allows me to kind of, you know, then focus in on what's in front of me right at the moment. I'll give you an example that's not really about attention, but it's about, like, what's the best way for me to achieve a state of relaxation? So, I went on a lovely rafting trip in Idaho this past summer. I have a ZOLEO satellite communicator. This is basically a thing that interacts with your phone and interacts with a satellite. You can't make phone calls, but you can send and receive text messages. And I brought that along because I felt that I would probably be more relaxed knowing that if something really bad happened, people could reach me, than being completely out of touch.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So for me, that sort of middle space of some contact, otherwise, I'm going to be, you know, a heightened state of arousal when I come back out from the remote wilderness.

Andrew Huberman: Mm-hmm.

Andrew Huberman: You know, I think about people like my niece's generation. She's, you know, late teens, about to hit her 20s, and to completely remove oneself from smartphone technology in that age bracket sets up a kind of return to communication with others that probably involves a lot of stress.

Jennifer Groh: Yeah.

Jennifer Groh: Uh-huh.

Jennifer Groh: Yeah.

Andrew Huberman: Like, what are you going to get? It's like opening your email after a two-month vacation.

Jennifer Groh: Right.

Jennifer Groh: Exactly.

Andrew Huberman: And you just can't do that when you're running a lab.

Jennifer Groh: And then, the re-entry is so painful of that sort of onslaught of things and even emotional messages from people that if you read them in order, you know, and it's five or six days ago, and you're like, "Ugh!"

Andrew Huberman: Mm-hmm.

Jennifer Groh: Then you see follow-up messages, and things got resolved without you, usually. Fingers crossed. Usually, that's what happens. It so rapidly wipes out that state of calm that you can get from being out in the wilderness.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Yeah, I will periodically go into the wilderness. I did this recently, and I didn't notify enough people. But I notified the critical ones. And people don't like it.

Jennifer Groh: Mm-hmm.

Jennifer Groh: No. Well, I wish we could set up an auto-reply for text messaging. That would make me feel more calm.

Andrew Huberman: What I'm hearing from you is that you embrace the natural peaks and valleys in your attention. You've figured out what works for you in different contexts. It's not like it's always one sentence, a break, one sentence... It really depends.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And I think we hear a lot about how phones are the problem.

Jennifer Groh: Mm-hmm.

Andrew Huberman: We had Jonathan Haidt on this podcast. He's the most vocal out there, and I really support his message, so I want to be clear about that.

Jennifer Groh: Yeah.

Andrew Huberman: But for many people, it's just not feasible. People with kids, people with jobs, people outside the elementary and high school classroom, people need to be accessible if something critical comes through, and I think that's really the thing, is it's just very unfiltered, and that's what is leading to so many challenges with getting real work done.

Jennifer Groh: Right.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah. I think the movement to get them out of schools is good.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I felt like we, as parents, had no choice, that our children were being... It was a required part of what they had to do in the classroom, was to have access to the internet on something.

Andrew Huberman: Mm-hmm.

Jennifer Groh: You know, at least recognizing that problem and being a little more thoughtful about it, and the cases where schools have decided to keep the phones all the way out of the classroom, I think, certainly that's worth trying, and let's see how it goes.

Andrew Huberman: Mm-hmm.

Jennifer Groh: So I try to be aware, what am I getting from the phone at any particular moment in time or for any particular purpose? So, I feel pretty good about texting with my friends and family.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I feel great about using it to have access to public transit in the cities that I'm not familiar with.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Love that.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Love it as a travel tool, love it for booking plane flights and things like that. So convenient that I can do that. It frees up time that I would otherwise be at my computer doing some deeper work.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Okay, now, I can do that on my phone somewhere when I just have a free moment. So I love that. I think it's useful for me to try to be aware of, what do I want to get out of my phone right now, and am I just bored? You know, if I'm using it because I'm just bored, that's the thing that, okay, let me see if I can swap it out for something that might be a little healthier, like listening to a podcast, or listening to an audiobook, or reading a book on my phone, or reading an actual book. That can be good. I've tried to set myself up with some exit paths from being on my phone. Like, okay, yes, I will admit, it's one of the first things I do in the morning. I know I should go outside and touch grass and get some sun.

Andrew Huberman: Get some sunlight.

Jennifer Groh: I know. I know.

Andrew Huberman: Set that circadian rhythm.

Jennifer Groh: Yeah. Well, I often wake up before it's light out, so I have to wait for that anyway. So, for example, I'll do my one or two hits on Duolingo, and one or two other language apps.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I'll do a couple of my favorite games on the New York Times Games site. But those are usually things that, like, there's a sense of satiety, there's a sense of being finished.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Like, it's not an endless scroll.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I have completed one lesson, so there's a moment to get off the phone.

Andrew Huberman: Mm-hmm.

Jennifer Groh: I'd love to have an app that limited the endless scroll on social media, like an interface to social media that sort of served me maybe some designated number of posts, and then I would have to take some explicit action to get more, and that might help me get off.

Andrew Huberman: Mm-hmm.

Andrew Huberman: Yeah, based on the dopamine literature and everything I know about the brain, I decided that any activity that has a seamless on-ramp to full attention, and that has no endpoint, you mentioned endpoint, is the thing to be really careful of.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Mm-hmm.

Jennifer Groh: Yeah.

Andrew Huberman: So, the seamless on-ramp to grabbing it, full attention. It's like ball bearing from flat surface into the trench. There's no work involved.

Jennifer Groh: Right.

Andrew Huberman: And then you're there, and you can stay there as long as you want. It doesn't kick you out. You have to kick yourself out, or life kicks you out because you didn't go do something or something happens.

Jennifer Groh: Yeah.

Jennifer Groh: Right.

Andrew Huberman: So, that's key. So that's the slot machine analogy. It's very easy to play a slot machine.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And, it's very easy to spend out all your money on a slot machine. And so they created this thing, like, where you can go get more money out of a machine, right? So, you can continue playing on the other machine, and that's the same thing, but it's how seamless it is. Like, you don't even need to learn the card game to gamble.

Jennifer Groh: Mm-hmm.

Andrew Huberman: You just have to know how to pull a lever, press a button. Social media is a bit the same. My solution to the social media thing is I took an old phone. I put X and Instagram on that phone.

Jennifer Groh: Uh-huh.

Andrew Huberman: Those are the only two social media platforms I use, and if somebody sends me something on my phone, like it's social media, I can't go to it. So, I have to segregate social media.

Jennifer Groh: Got it.

Andrew Huberman: I have a social media phone, and I only get a certain amount of time with it.

Jennifer Groh: You can't get into your social media from a browser?

Andrew Huberman: No.

Jennifer Groh: Okay.

Andrew Huberman: No. So, if someone sends me an Instagram post, I click on it, I can't see it. I get that error signal, "Sign in," and I'm not signed in. It's like-

Jennifer Groh: Oh! You're not signed in.

Andrew Huberman: I don't even know my password.

Jennifer Groh: Okay.

Andrew Huberman: It's written someplace.

Jennifer Groh: Yeah.

Andrew Huberman: But I have a password generator. It updates all the time anyway, so...

Jennifer Groh: Yeah. Okay, I see how you would do that.

Andrew Huberman: So, the solution was to create-

Jennifer Groh: To log out and then have a phone that just had those-

Andrew Huberman: I don't even have the apps on that phone.

Jennifer Groh: Yeah, I have never-

Andrew Huberman: I would have to install the apps. I'd have to sign in.

Jennifer Groh: Right.

Andrew Huberman: I'd have to find my password, which my team knows that's never going to happen. I'd have to log in, so I just don't-

Jennifer Groh: Right.

Jennifer Groh: Too many keystrokes.

Andrew Huberman: I just don't have access to it.

Jennifer Groh: Yeah.

Andrew Huberman: Unless I'm on that phone, so-

Jennifer Groh: That's great. I think that's perfect.

Andrew Huberman: I mean, it works for me.

Jennifer Groh: Works for you, yeah. Great.

Andrew Huberman: Works for me. But I think having systems like this is, like, going to be required for most people because I don't think anyone's going to create the app that you're looking for.

Jennifer Groh: Yeah.

Jennifer Groh: Right. No.

Andrew Huberman: I hope they do, but I don't think they're going to.

Jennifer Groh: Right. Yeah.

Andrew Huberman: So, your lab is still super productive, so when you're in the lab, presumably, and interacting with students and writing grants and stuff, all this stuff falls away, right? Because inside the lab context, it's like your workshop. I'm guessing that makes it much easier.

Jennifer Groh: Mm-hmm.

Jennifer Groh: That's true. That's true. Yeah, when I'm interacting with people at work, or I'm in the actual lab, it does, it all falls away.

Andrew Huberman: Mm-hmm.

Jennifer Groh: Yeah, the cues to stay focused are very strong.

Andrew Huberman: I knew we were going to talk about the auditory system.

Jennifer Groh: Mm-hmm.

Andrew Huberman: And we did. I knew we were going to talk about the visual system, and we did, and I knew we were going to talk about their integration. What I did not expect, but I'm so delighted happened, is that you brought us into the realm of true multi-sensory integration, and the extent to which our physical environment shapes the way that our brain works. And our brain is also creating its own internal environment, and that we have a lot more control over that than perhaps we think, unless we just leave it to circumstances, which is really the takeaway that, at least, I pulled from this last portion of our conversation. So, thank you so much for coming here and explaining this. We've not talked about multi-sensory integration before.

Andrew Huberman: I started off by saying that, and now we have, and I'm so glad that you were the one to introduce it to us, because it's a fascinating aspect of how we work, and it's really the core mechanics of how we work. When we talk about thinking or working or focus, we're not just talking about vision or hearing. We're talking about their merge, so...

Jennifer Groh: Exactly. Thank you.

Andrew Huberman: It's really wonderful, and let me know how the experiment with the chickens go. Yeah. Yeah.

Jennifer Groh: Thank you so much. This has been great.

Andrew Huberman: No, well, I really enjoyed it. Thank you.

Jennifer Groh: Thank you.

Andrew Huberman: Thank you for joining me for today's discussion with Dr. Jennifer Groh. To learn more about her laboratory's work and to find a link to her excellent book entitled "Making Space: How the Brain Knows Where Things Are," please see the show note captions. If you're learning from and/or enjoying this podcast, please subscribe to our YouTube channel. That's a terrific zero-cost way to support us. In addition, please follow the podcast by clicking the Follow button on both Spotify and Apple.

Andrew Huberman: And on both Spotify and Apple, you can leave us up to a five-star review, and you can now leave us comments at both Spotify and Apple. Please also check out the sponsors mentioned at the beginning and throughout today's episode. That's the best way to support this podcast. If you have questions for me or comments about the podcast, or guests or topics that you'd like me to consider for the Huberman Lab podcast, please put those in the comments section on YouTube. I do read all the comments.

Andrew Huberman: For those of you that haven't heard, I have a new book coming out. It's my very first book. It's entitled "Protocols: An Operating Manual for the Human Body." This is a book that I've been working on for more than five years, and that's based on more than 30 years of research and experience, and it covers protocols for everything from sleep, to exercise, to stress control, protocols related to focus and motivation, and of course, I provide the scientific substantiation for the protocols that are included. The book is now available by presale at protocolsbook.com. There you can find links to various vendors. You can pick the one that you like best. Again, the book is called "Protocols: An Operating Manual for the Human Body."

Andrew Huberman: And if you're not already following me on social media, I am hubermanlab on all social media platforms, so that's Instagram, X, Threads, Facebook, and LinkedIn. And on all those platforms, I discuss science and science-related tools, some of which overlaps with the content of the Huberman Lab podcast, but much of which is distinct from the information on the Huberman Lab podcast. Again, it's hubermanlab on all social media platforms.

Andrew Huberman: And if you haven't already subscribed to our Neural Network Newsletter, the Neural Network Newsletter is a zero-cost monthly newsletter that includes podcast summaries as well as what we call protocols in the form of one to three-page PDFs that cover everything from how to optimize your sleep, how to optimize dopamine, deliberate cold exposure. We have a foundational fitness protocol that covers cardiovascular training and resistance training. All of that is available completely zero cost. You simply go to hubermanlab.com, go to the Menu tab in the top right corner, scroll down to Newsletter, and enter your email, and I should emphasize that we do not share your email with anybody.

Andrew Huberman: Thank you once again for joining me for today's discussion with Dr. Jennifer Groh. And last but certainly not least, thank you for your interest in science.