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David Eagleman on how we constructs reality, time perception, and The Secret Lives of the Brain


How our brain constructs reality

The conscious mind—which is the part of you that flickers to life when you wake up in the morning: that bit of you—it’s like a stowaway on a transatlantic steamship, that’s taking credit for the journey, without acknowledging all the engineering underfoot.

I think what this means when we’re talking about knowing ourselves is exactly
what it meant when people were trying to understand our place in the cosmos,
400 years ago, when Galileo discovered the moons of Jupiter and realized that, in fact, we’re not at the center of things, but instead we’re way out on a distant edge. That’s essentially the same situation we’re in, where we’ve fallen from the center of ourselves.

But in Galileo’s case, what that caused is we now have a much more nuanced view of the cosmos. As Carl Sagan was fond of saying, it’s more wondrous and subtle than we could have ever imagined. And I think it’s exactly the same thing going on with the brain: we’re falling from the center of the brain, but what we’re discovering is that it’s much more amazing than we could have ever thought when we imagined that we were the ones sort of at the center of everything and driving the boat. (…)

As we want to go on this journey of exploring what the heck we’re made out of, the first thing to do is to recognize that what you’re seeing out there is not actually reality. You’re not sort of opening your eyes, and voila, there’s the world. Instead, your brain constructs the world. Your brain is trapped in darkness inside of your skull, and all it ever sees are electrical and chemical signals. So all the colors you see, and so on, that doesn’t really exist; that’s an interpretation by your brain. (…)

All we’re actually doing is seeing an internal model of the world; we’re not seeing what’s out there, we’re seeing just our internal model of it. And that’s why, when you move your eyes around, all you’re doing is updating that model.

And for that matter, when you blink your eyes and there are 80 milliseconds of blackness there, you don’t notice that, either. Because it’s not actually about what’s coming in the eyes; it’s about your internal construction. And, in fact, as I mention in the book, we don’t even need our eyes to see. When you are asleep and dreaming, your eyes are closed, but you’re having full, rich visual experience —because it’s the same process of running your visual cortex, and then you believe that you are seeing. (…)

Because all the brain ever sees are these electrical and chemical signals, and it doesn’t necessarily know or care which ones are coming in through the eyes, or the ears, or the fingertips, or smell, or taste. All these things get converted just to electrical signals.

And so, it turns out what the brain is really good at—and the cortex in particular —is in extracting information that has some sort of useful correlation with things in the outside world. And so, if you feed, let’s say, visual input into your ears, you will figure out how to see through your ears. Because the brain doesn’t care how it gets there; all it cares about is, Oh, there’s structure to this data that I can extract. (…)

I think it’s sort of the most amazing thing about the way brains are built, is they’re constantly reconfiguring their own circuitry. (…)

It turns out that one of the main jobs of the brain is to save energy; and the way that it does this is by predicting what is going to come next. And if it sort of has a pretty good prediction of what’s happening next, then it doesn’t need to burn a lot of energy when that thing happens, because it’s already foreseen it. (…)

So, the job of the brain is to figure out what’s coming next; and if you have successfully done it, then there’s no point in consciousness being a part of what’s going on. (…)

Time perception

You’re not passively just watching the river of time flow by. Instead, just like with visual illusions, your brain is actively constructing time. (…)

When you can predict something, not only does your consciousness not come
online, but it feels like it goes very fast. So, driving to work is very fast; but the
very first time you did it, it seemed to take very long time. And it’s because of the
novelty and the amount of energy you had to burn the first time you did it—
before you were able to predict it.

Essentially what prediction means, if it’s something you’re doing a lot, is that
you’re actually reconfiguring the circuitry of the brain. You’re actually getting
stuff down into the circuitry, which gives you speed and efficiency, but at the cost
of conscious access. (…)

It’s not only the way we see vision and time, but it’s all of our cognition: it’s our morals, it’s what we’re attracted to, it’s what we believe in. All of these things are served up from these subterranean caverns of the mind. We often don’t have any access to what’s going on down there, and why we believe the things we do, why we act the way we do. (…)

The “illusion of truth”

You give people statements to rate the truth value of, and then you bring them back a while later and you give them more statements to say whether they’re true or false, and so on. But it turns out that if you repeat some of the statements from the first time to the second time, just because the people have heard them before, whether or not it’s true and whether or not they even marked it as false last time, because they’re hearing it again— unconsciously they know they’ve heard it before—they’re more likely to rate it as true now. (…)

I think this is part of the brain toolbox that children need: to really practice and learn skepticism and critical thinking skills. (…)

Some thoughts aren’t thinkable, because of the way that thoughts are constrained by our biology

Yes. As far as thoughts that we’re not able to think, that’s an idea that I just love to explore, because there’s all kinds of stuff we can’t see. Just as an example, if you take the electromagnetic radiation spectrum, what we call visible light is just one ten-billionth of that spectrum. So, we’re only seeing a very tiny sliver of that, because we have biological receptors that are tuned to that little part of the spectrum. But radio signals, and cell phone signals, and television signals, all that stuff is going right through your body, because you happen not to have biological receptors for that part of the spectrum.

So, what that means is that there’s a particular slice of the world that you can see. And what I wanted to explore in the book is that there’s also a slice of the world that you can think. In other words, because of evolutionary pressures, our psychology has been carved to think certain thoughts—this is the field known as evolutionary psychology—and that means there are other thoughts that are just like the cell phone signals, and radio signals, and so on, that we can’t even access.

Just as an example, try being sexually attracted to something that you’re not—like a chicken or a frog. But chickens and frogs find that to be the greatest thing in the world, to look at another chicken or frog. We only find that with humans. So, different species, which have otherwise pretty similar brains, have these very specific differences about the kinds of thoughts they can think. (…)

As far as nature vs. nurture goes, the answer nowadays is always both. It’s sort of a dead question to ask—nature vs. nurture—because it is absolutely true that we do not come to the table as a blank slate; we have a lot of stuff that we come to the table with predisposed. But the whole rest of the process is an unpacking of the brain by world experience. (…)

The brain as the team of rivals. Rational vs. emotional

So, the way your brain ends up in the end is a very complicated tangle of genetics and environment. And environment includes, not only all of your childhood experiences and so on, but your in utero environment, toxins in the air, the things that you eat, experiences of abuse, and all of that stuff—and your culture; your culture has a lot to do with the way your brain gets wired up. (…)

One of the culminating issues in the book is that your brain is really like a team of rivals, where you have these different neural subpopulations that are always battling it out to control the one-output channel of your behavior; and you’ve got all these different networks that are fighting it out. And so, there are parts of your brain that can be xenophobic, and other parts of your brain that maybe decide to overwrite that, and they’re not xenophobic. And I think this gives us a much more nuanced view, in the end, of who we are, and also who other people are. (…)

When people do neuroimaging studies, you can actually find situations where it looks like you have some parts that are doing essentially a math problem in the brain, and other parts that really care about how things feel, and how they’ll make the body feel. And you can image these different networks, and you can also see when they’re fighting one another when trying to do some sort of moral decision-making.

So, probably the best way for us to look at it is that when we talk about reason vs. emotion, we’re talking about sort of a summary—sort of a shorthand way of talking about these different neural networks. And, of course, decisions can be much more complicated than that, often. But sometimes they can be essentially boiled down to that.

It’s funny; the ancient Greeks also felt that this was the right way to divide it.
Again, it’s an oversimplification, but the Greeks had this idea that life is like
you’re a charioteer, and you’re holding the white horse of reason and the black horse of passion, and they’re both always trying to pull you off the road in different directions, and your job is to keep down the middle. And that’s about right. They had some insight there into that you do have these competing networks. (…)

The field of artificial intelligence

The field of artificial intelligence has become stuck, and I’m trying to figure
out why. I think it’s because when programmers are trying to make a robot do something, they come up with solutions: like here’s how you find the block of
wood, here’s how you grip the block of wood, here’s how you stack the block of
wood, and so on. And each time they make a little subroutine to take care of a
little piece of the problem; then they say, OK, good; that part’s done.

But Mother Nature never does that. Mother Nature chronically reinvents things all the time—accidentally. Just by mutation, there are always new ways to do things, like detect motion, or control muscles, or whatever it is that it’s trying to do—pick up on new energy sources, and so on. And as a result, what you have are multiple ways of solving problems in real biological creatures.

They don’t divide up neatly into little modules, the same way that a computer
program does, but instead, for example, in the mammalian cortex it appears that Mother Nature probably came up with about three or four different ways to detect motion. And all of these act like parties in the neural parliament. They all sort of think that they know how to detect motion best, and they battle it out with the other parties.

And so, I think this is one of the main lessons that we get, when we look for it, in what happens when we see brain damage in people. You can lose aspects of your vision and not lose other aspects; or, often, you can get brain damage and you don’t see a deficit at all, even though you’ve just sort of bombed out part of what you would expect to give a deficit.

In other words, you have this very complicated interaction of these different
parties that are battling it out. And I think they, in general, don’t divide neatly
along the cortical and subcortical division, but instead, whether in lizard brains
or in our brains, these networks can be made up of subcortical and cortical parts
together. (…)

The illusion we have that we have control

The analogy of a young monarch who takes the throne of his country, and takes credit for the glory of the country without thinking about the thousands of workers who are making it all work. And that’s essentially the situation we’re in.

Take, just as an example, when you have an idea, you say, ‘Oh, I just thought of
something.’ But it wasn’t actually you that thought of it. Your brain has been
working on that behind the scenes for hours or days, consolidating information,
putting things together, and finally it serves up something to you. It serves up an
idea; and then you take credit for it. But this whole things leads to this very
interesting question about the illusion we have that we have control. (…)

What does this mean for responsibility?

I think what it means is that when we look at something like the legal system, something like blameworthiness is actually the wrong question for us to ask. I mentioned before that brains end up being an end result of a very complicated process of genes intertwining with environment. So, in the end, when there’s a brain standing in front of the judge’s bench, it doesn’t matter for us to say, OK, well, are you blameworthy; to what extent are you blameworthy; to what extent was it your biology vs. you; because it’s not clear that there’s any meaningful difference between those two things, anyway.

I’m not saying this forgives anybody. We still have to take people off the street if they’re breaking the law. But what it means is that asking the question of blameworthiness isn’t where we should be putting our time. Instead, all we need to be doing is having a forward-looking legal system, where we say what do we do with you from here?

We don’t care how you got here, because we can’t ever know. It might have been
in utero cocaine poisoning, childhood abuse, lead paint on the walls, and all of
these other things that influenced your brain development, but we can’t untangle
that. And it’s not anybody’s fault. It’s not your fault or anybody else’s. But we
can’t do anything about it.

So, all we need to do is say, given the kind of person you are now, what is the
probability of recidivism. In other words, how likely are you to transfer this
behavior to a future situation and re-offend? And then we can predicate sentence
length on that probability of re-offense. And, equally as importantly, along with
customized sentencing, we can have customized rehabilitation.

So, there are lots of things that can go wrong with people’s brains that we can
usefully address, and try to help people, instead of throwing everybody in jail. As it stands now, 30% of the prison population has mental illness. Not only is that not a humane way for us to treat our mentally ill and make a de facto healthcare system, but it’s also not cost-effective.

And it’s also criminogenic—meaning it causes more crime. Because everybody
knows when you put people in jail, that limits their employment opportunities, it
breaks their social circles, and they end up coming back to the jail, more often
than not. So, it’s very clear how the legal system should be straightening itself out, just to make itself forward-looking, and saying, OK, all we need to do is get good at assessing risk into the future. (…)

A neural parliament

One of the really amazing lessons is this bit about being a neural parliament,
and not being made up of just one thing. I think this gives us a much better view
of why we can argue with ourselves, and curse at ourselves, and contract with
ourselves, and why we can do things where we look back and we think, Wow,
how did I do that? I’m not the kind of person who would do that.

But, in fact, you are many people. As Walt Whitman said, “I am large, I contain multitudes.” So, I think this gives us a better view of ourselves, and it also tells us ways to set up our own behavior to become the kind of people we want to be, by thinking about how to structure things in our life so that the short-term parties that are interested in instant impulse gratification—so that they don’t always win the battle.”

David Eagleman, neuroscientist at Baylor College of Medicine, where he directs the Laboratory for Perception and Action and the Initiative on Neuroscience and Law, Interview with Dr. David Eagleman, Author of Incognito: The Secret Lives of the Brain, Brain Science Podcast, Episode #75, Originally Aired 7/8/2011 (transcript in pdf) (Illustration source: David Plunkert for TIME)

The brain… it makes you think. Doesn’t it?

David Eagleman: “A person is not a single entity of a single mind: a human is built of several parts, all of which compete to steer the ship of state. As a consequence, people are nuanced, complicated, contradictory. We act in ways that are sometimes difficult to detect by simple introspection. To know ourselves increasingly requires careful studies of the neural substrate of which we are composed. (…)

Raymond Tallis: Of course, everything about us, from the simplest sensation to the most elaborately constructed sense of self, requires a brain in some kind of working order. (…)

[But] we are not stand-alone brains. We are part of community of minds, a human world, that is remote in many respects from what can be observed in brains. Even if that community ultimately originated from brains, this was the work of trillions of brains over hundreds of thousands of years: individual, present-day brains are merely the entrance ticket to the drama of social life, not the drama itself. Trying to understand the community of minds in which we participate by imaging neural tissue is like trying to hear the whispering of woods by applying a stethoscope to an acorn. (…)

David Eagleman: The uses of neuroscience depend on the question being asked. Inquiries about economies, customs, or religious wars require an examination of what transpires between minds, not just within them. Indeed, brains and culture operate in a feedback loop, each influencing the other.

Nonetheless, culture does leave its signature in the circuitry of the individual brain. If you were to examine an acorn by itself, it could tell you a great deal about its surroundings – from moisture to microbes to the sunlight conditions of the larger forest. By analogy, an individual brain reflects its culture. Our opinions on normality, custom, dress codes and local superstitions are absorbed into our neural circuitry from the social forest around us. To a surprising extent, one can glimpse a culture by studying a brain. Moral attitudes toward cows, pigs, crosses and burkas can be read from the physiological responses of brains in different cultures.

Beyond culture, there are fruitful questions to be asked about individual experience. Your experience of being human – from thoughts to actions to pathologies to sensations – can be studied in your individual brain with some benefit. With such study, we can come to understand how we see the world, why we argue with ourselves, how we fall prey to cognitive illusions, and the unconscious data-streams of information that influence our opinions.

How did I become aware enough about unawareness to write about it in Incognito? It was an unlikely feat that required millennia of scientific observation by my predecessors. An understanding of the limitations of consciousness is difficult to achieve simply by consulting our intuition. It is revealed only by study.

To be clear, this limitation does not make us equivalent to automatons. But it does give a richer understanding of the wellspring of our ideas, moral intuitions, biases and beliefs. Sometimes these internal drives are genetically embedded, other times they are culturally instructed – but in all cases their mark ends up written into the fabric of the brain. (…)

Neuroscience is uncovering a bracing view of what’s happening below the radar of our conscious awareness, but that makes your life no more “helpless, ignorant, and zombie-like” than whatever your life is now. If you were to read a cardiology book to learn how your heart pumps, would you feel less alive and more despondently mechanical? I wouldn’t. Understanding the details of our own biological processes does not diminish the awe, it enhances it. Like flowers, brains are more beautiful when you can glimpse the vast, intricate, exotic mechanisms behind them.”

David Eagleman, neuroscientist at Baylor College of Medicine, where he directs the Laboratory for Perception and Action, bestselling author

Raymond Tallis, British philosopher, secular humanist, poet, novelist, cultural critic, former professor of geriatric medicine at Manchester University

The brain… it makes you think. Doesn’t it?, The Guardian, The Observer, 29 April 2012.

See also:

Time and the Brain. Eagleman: ‘Time is not just as a neuronal computation—a matter for biological clocks—but as a window on the movements of the mind’
David Eagleman on the conscious mind
David Eagleman on Being Yourselves, lecture at Conway Hall, London, 10 April 2011.
The Experience and Perception of Time, Stanford Encyclopedia of Philosophy
Your brain creates your sense of self, incognito, CultureLab, Apr 19, 2011.
Dean Buonomano on ‘Brain Bugs’ - Cognitive Flaws That ‘Shape Our Lives’
Iain McGilchrist on The Divided Brain and the Making of the Western World
Daniel Kahneman: The Marvels and the Flaws of Intuitive Thinking
The Relativity of Truth - a brief résumé, Lapidarium
Timothy D. Wilson on The Social Psychological Narrative: ‘It’s not the objective environment that influences people, but their constructs of the world’
☞ David Eagleman, Your Brain Knows a Lot More Than You Realize, DISCOVER Magazine, Oct 27, 2011
☞ David Eagleman, Henry Markram, Will We Ever Understand the Brain?, California Academy of Sciences San Francisco, CA, video, 11.02.2011
☞ Bruce Hood, The Self Illusion: How the Brain Creates Identity, May, 2012
Mind & Brain tag on Lapidarium