The Brain: The Story of You

by David Eagleman

we rigged up each volunteer so we’d be able to measure their emotional response. We hooked them up with a device to measure the galvanic skin response (GSR), a useful proxy for anxiety: the more your sweat glands open, the higher your skin conductance will be. (This is, by the way, the same technology used in a lie detector, or polygraph test.)

The shape of the hills and valleys in the brain is largely conserved across people – but the finer details give a personal and unique reflection of where you’ve been and who you are now. Although most of the changes are too small to detect with the naked eye, everything you’ve experienced has altered the physical structure of your brain – from the expression of genes to the positions of molecules to the architecture of neurons. Your family of origin, your culture, your friends, your work, every movie you’ve watched, every conversation you’ve had – these have all left their footprints in your nervous system. These indelible, microscopic impressions accumulate to make you who you are, and to constrain who you can become.

Brewer reports that after a few days of wearing the goggles, people develop an internal sense of a new left and an old left, and a new right and an old right. After a week, they can move around normally, the way Brian could, and they lose the concept of which right and left were the old ones and new ones. Their spatial map of the world alters. By two weeks into the task, they can write and read well, and they walk and reach with the proficiency of someone without goggles. In that short time span, they master the flipped input. The brain doesn’t really care about the details of the input; it simply cares about figuring out how to most efficiently move around in the world and get what it needs. All the hard work of dealing with the low-level signals is taken care of for you. If you ever get a chance to wear prism goggles, you should. It exposes how much effort the brain goes through to make vision seem effortless.

There’s an interesting upshot to automatized skills: attempts to consciously interfere with them typically worsen their performance. Learned proficiencies – even very complex ones – are best left to their own devices.

Our brains constantly pull information from the environment and use it to steer our behavior, but often the influences around us are not recognized. Take an effect called “priming”, in which one thing influences the perception of something else. For example, if you’re holding a warm drink you’ll describe your relationship with a family member more favorably; when you’re holding a cold drink, you’ll express a slightly poorer opinion of the relationship. Why does this happen? Because the brain mechanisms for judging intrapersonal warmth overlap with the mechanisms for judging physical warmth, and so one influences the other. The upshot is that your opinion about something as fundamental as your relationship with your mother can be manipulated by whether you take your tea hot or iced. Similarly, when you are in a foul-smelling environment, you’ll make harsher moral decisions – for example, you’re more likely to judge that someone else’s uncommon actions are immoral. In another study, it was shown that if you sit in a hard chair you’ll be a more hard-line negotiator in a business transaction; in a soft chair you’ll yield more.

The key to the Ulysses contract is recognizing that we are different people in different contexts. To make better decisions, it’s important not only to know yourself but all of your selves.

Our decisions are equally influenced when it comes to how we act with our romantic partners. Consider the choice of monogamy – bonding and staying with a single partner. This would seem like a decision that involves your culture, values, and morals. All that is true, but there’s a deeper force acting on your decision making as well: your hormones. One in particular, called oxytocin, is a key ingredient in the magic of bonding. In one recent study, men who were in love with their female partners were given a small dose of extra oxytocin. They were then asked to rate the attractiveness of different women. With the extra oxytocin, the men found their partners more attractive – but not other women. In fact, the men kept a bit more physical distance from an attractive female research associate in the study. Oxytocin increased bonding to their partner.

Using fast computational techniques in the scanner, we can measure which network is winning: the short-term thinking of the craving network, or the long-term thinking of the impulse control or suppression network. We give Karen real-time visual feedback in the form of a speedometer so she can see how that battle is going. When her craving is winning, the needle is in the red zone; as she successfully suppresses, the needle moves to the blue zone. She can then use different approaches to discover what works to tip the balance of these networks. By practicing over and over, Karen gets better at understanding what she needs to do to move the needle. She may or may not be consciously aware of how she’s doing it, but by repeated practice she can strengthen the neural circuitry that allows her to suppress. This technique is still in its infancy, but the hope is that when she’s next offered crack she’ll have the cognitive tools to overcome her immediate cravings if she wants to. This training does not force Karen to behave in any particular way; it simply gives her the cognitive skills to have more control over her choice, rather than to be a slave to her impulses.

Decision making lies at the heart of everything: who we are, what we do, how we perceive the world around us. Without the ability to weigh alternatives, we would be hostages to our most basic drives. We wouldn’t be able to wisely navigate the now, or plan our future lives. Although you have a single identity, you’re not of a single mind: instead, you are a collection of many competing drives. By understanding how choices battle it out in the brain, we can learn to make better decisions for ourselves, and for our society.

Genocide is only possible when dehumanization happens on a massive scale, and the perfect tool for this job is propaganda: it keys right into the neural networks that understand other people, and dials down the degree to which we empathize with them. We’ve seen that our brains can be manipulated by political agendas to dehumanize other people, which can then lead to the darkest side of human acts. But is it possible to program our brains to prevent this? One possible solution lies in a 1960s experiment that was conducted not in a science lab, but in a school.

In this age of digital hyperlinking, it’s more important than ever to understand the links between humans. Human brains are fundamentally wired to interact: we’re a splendidly social species. Although our social drives can sometimes be manipulated, they also sit squarely at the center of the human success story. You might assume that you end at the border of your skin, but there’s a sense in which there’s no way to mark the end of you and the beginning of all those around you. Your neurons and those of everyone on the planet interplay in a giant, shifting super-organism. What we demarcate as you is simply a network in a larger network. If we want a bright future for our species, we’ll want to continue to research how human brains interact – the dangers as well as the opportunities. Because there’s no avoiding the truth etched into the wiring of our brains: we need each other.

In 1714, Gottfried Wilhelm Leibniz argued that matter alone could never produce a mind. Leibniz was a German philosopher, mathematician, and scientist who is sometimes called “the last man who knew everything”. To Leibniz, brain tissue alone could not have an interior life. He suggested a thought experiment, known today as Leibniz’s Mill. Imagine a large mill. If you were to walk around inside of it, you would see its cogs and struts and levers all moving, but it would be preposterous to suggest that the mill is thinking or feeling or perceiving. How could a mill fall in love or enjoy a sunset? A mill is just made of pieces and parts. And so it is with the brain, Leibniz asserted. If you could expand the brain to the size of a mill and stroll around inside it, you would only see pieces and parts. Nothing would obviously correspond to perception. Everything would simply be acting on everything else. If you wrote down every interaction, it wouldn’t be obvious where thinking and feeling and perceiving reside.

If biological algorithms are the important part of what makes us who we are, rather than the physical stuff, then it’s a possibility that we will someday be able to copy our brains, upload them, and live forever in silica. But there’s an important question here: is it really you? Not exactly. The uploaded copy has all your memories and believes it was you, just there, standing outside the computer, in your body. Here’s the strange part: if you die and we turn on the simulation one second later, it would be a transfer. It would be no different to beaming up in Star Trek, when a person is disintigrated, and then a new version is reconstituted a moment later. Uploading may not be all that different from what happens to you each night when you go to sleep: you experience a little death of your consciousness, and the person who wakes up on your pillow the next morning inherits all your memories, and believes him or herself to be you.

Maybe what you would choose for your simulation is something very much like your present life on Earth, and that simple thought has led several philosophers to wonder whether we’re already living in a simulation. While that idea seems fantastical, we already know how easily we can be fooled into accepting our reality: every night we fall asleep and have bizarre dreams – and while we’re there we believe those worlds entirely. Questions about our reality are not new. Two thousand three hundred years ago, the Chinese philosopher Chuang Tzu dreamt he was a butterfly. Upon waking, he considered this question: how would I know if I was Chuang Tzu dreaming I’m a butterfly – or instead, if right now I’m a butterfly dreaming I’m a man named Chuang Tzu?

Only one thing is certain: our species is just at the beginning of something, and we don’t fully know what it is. We’re at an unprecedented moment in history, one in which brain science and technology are co-evolving. What happens at this intersection is poised to change who we are. For thousands of generations, humans have lived the same sort of life cycle over and over: we’re born, we control a fragile body, we enjoy a small strip of sensory reality, and then we die. Science may give us the tools to transcend that evolutionary story. We can now hack our own hardware, and as a result our brains don’t need to remain as we’ve inherited them. We’re capable of inhabiting new kinds of sensory realities and new kinds of bodies. Eventually we may even be able to shed our physical forms altogether. Our species is just now discovering the tools to shape our own destiny. Who we become is up to us.