Incognito: The Secret Lives of the Brain

by David Eagleman

Deliciousness is simply an index of usefulness.

Instead of reality being passively recorded by the brain, it is actively constructed by it.

MANTRA OF THE EVOLVING BRAIN: BURN REALLY GOOD PROGRAMS ALL THE WAY DOWN TO THE DNA

He suggested instead that human behavior may be more flexibly intelligent than that of other animals because we possess more instincts than they do, not fewer.

Instincts differ from our automatized behaviors (typing, bicycle riding, serving a tennis ball) in that we didn’t have to learn them in our lifetime. We inherited them. Our innate behaviors represent ideas so useful that they became encoded into the tiny, cryptic language of DNA.

The key point here is that the specialized, optimized circuitry of instinct confers all the benefits of speed and energy efficiency, but at the cost of being further away from the reach of conscious access.

“instinct blindness”:

We’ve seen in this chapter that our deepest instincts, as well as the kinds of thoughts we have and even can have, are burned into the machinery at a very low level. “This is great news,” you might think. “My brain is doing all the right things to survive, and I don’t even have to think about them!” True, that is great news. The unexpected part of the news is that the conscious you is the smallest bit-player in the brain.

And can you tell me, caller, that you’re not a player on the stage of life—playing out your allotted role? He can leave at any time. If his was more than just a vague ambition, if he were absolutely determined to discover the truth, there’s no way we could prevent him. I think what really distresses you, caller, is that ultimately

Is there any reason to believe that it’s not possible to have both racist and nonracist parts of the brain?

The emotional networks are absolutely required to rank your possible next actions in the world:

In earlier times in our evolution, there was no real way to interact with others at a distance any farther than that allowed by hands, feet, or possibly a stick. That distance of interaction was salient and consequential, and this is what our emotional reaction reflects.

Sigmund Freud noted that arguments stemming from the intellect or from morality are weak when pitted against human passions and desires,20 which is why campaigns to “just say no” or practice abstinence will never work. It has also been proposed that this imbalance of reason and emotion may explain the tenacity of religion in societies: world religions are optimized to tap into the emotional networks, and great arguments of reason amount to little against such magnetic pull. Indeed, the Soviet attempts to squelch religion were only partially successful, and no sooner had the government collapsed than the religious ceremonies sprang richly back to life.

Freely made decisions that bind you in the future are what philosophers call a Ulysses contract.

Researchers came to realize, over time, that the two hemispheres have somewhat different personalities and skills—this includes their abilities to think abstractly, create stories, draw inferences, determine the source of a memory, and make good choices in a gambling game. Roger Sperry, one of the neurobiologists who pioneered the split-brain studies (and garnered a Nobel Prize for it), came to understand the brain as “two separate realms of conscious awareness; two sensing, perceiving, thinking and remembering systems.” The two halves constitute a team of rivals: agents with the same goals but slightly different ways of going about it.

In 1976, the American psychologist Julian Jaynes proposed that until late in the second millennium B.C.E., humans had no introspective consciousness, and that instead their minds were essentially divided into two, with their left hemispheres following the commands from their right hemispheres.29 These commands, in the form of auditory hallucinations, were interpreted as voices from the gods. About three thousand years ago, Jaynes suggests, this division of labor between the left and right hemispheres began to break down. As the hemispheres began to communicate more smoothly, cognitive processes such as introspection were able to develop. The origin of consciousness, he argues, resulted from the ability of the two hemispheres to sit down at the table together and work out their differences. No one yet knows whether Jaynes’s theory has legs, but the proposal is too interesting to ignore.

hemispherectomy,

An advantage of overlapping domains can be seen in the newly discovered phenomenon of cognitive reserve.

What does alien hand syndrome tell us? It unmasks the fact that we harbor mechanical, “alien” subroutines to which we have no access and of which we have no acquaintance. Almost all of our actions—from producing speech to picking up a mug of coffee—are run by alien subroutines, also known as zombie systems. (I use these terms interchangeably: zombie emphasizes the lack of conscious access, while alien emphasizes the foreignness of the programs.)

Alien hand syndrome also tells us that under normal circumstances, all the automated programs are tightly controlled such that only one behavioral output can happen at a time. The alien hand highlights the normally seamless way in which the brain keeps a lid on its internal conflicts. It requires only a little structural damage to uncover what is happening beneath. In other words, keeping the union of subsystems together is not something the brain does without effort—instead, it is an active process. It is only when factions begin to secede from the union that the alienness of the parts becomes obvious.

We are constantly fabricating and telling stories about the alien processes running under the hood.

anosognosia.

Minds seek patterns. In a term introduced by science writer Michael Shermer, they are driven toward “patternicity”—the attempt to find structure in meaningless data.42 Evolution favors pattern seeking, because it allows the possibility of reducing mysteries to fast and efficient programs in the neural circuitry.

consider dreams,

All these moments are dynamically woven into a story, and this is why after a night of random activity you wake up, roll over to your partner, and feel as though you have a bizarre plot to relate.

From an evolutionary point of view, the purpose of consciousness seems to be this: an animal composed of a giant collection of zombie systems would be energy efficient but cognitively inflexible.

In the animal kingdom, most animals do certain things very well (say, prying seeds from the inside of a pine cone), while only a few species (such as humans) have the flexibility to dynamically develop new software.

what is a secret, neurobiologically?

Within the team-of-rivals framework, a secret is easily understood: it is the result of struggle between competing parties in the brain. One part of the brain wants to reveal something, and another part does not want to. When there are competing votes in the brain—one for telling, and one for withholding—that defines a secret. If no party cares to tell, that’s merely a boring fact; if both parties want to tell, that’s just a good story. Without the framework of rivalry, we would have no way to understand a secret.*** The reason a secret is experienced consciously is because it results from a rivalry. It is not business as usual, and therefore the CEO is called upon to deal with it.

As you have doubtless noticed, venting a secret is usually done for its own sake, not as an invitation for advice. If the listener spots an obvious solution to some problem revealed by the secret and makes the mistake of suggesting it, this will frustrate the teller—all she really wanted was to tell. The act of telling a secret can itself be the solution. An open question is why the receiver of the secrets has to be human—or human-like, in the case of deities. Telling a wall, a lizard, or a goat your secrets is much less satisfying.

The main lesson of this chapter is that you are made up of an entire parliament of pieces and parts and subsystems. Beyond a collection of local expert systems, we are collections of overlapping, ceaselessly reinvented mechanisms, a group of competing factions. The conscious mind fabricates stories to explain the sometimes inexplicable dynamics of the subsystems inside the brain. It can be disquieting to consider the extent to which all of our actions are driven by hardwired systems, doing what they do best, while we overlay stories about our choices.

The lesson is clear: a slight change in the balance of brain chemistry can cause large changes in behavior. The behavior of the patient cannot be separated from his biology. If we like to believe that people make free choices about their behavior (as in, “I don’t gamble because I’m strong-willed”), cases like Alex the pedophile, the frontotemporal shoplifters, and the gambling Parkinson’s patients may encourage us to examine our views more carefully. Perhaps not everyone is equally “free” to make socially appropriate choices.

actions. This view of the practical reasoner is both intuitive and—as should be clear by this point in the book—deeply problematic. There is a tension between biology and law on this intuition. After all, we are driven to be who we are by vast and complex biological networks. We do not come to the table as blank slates, free to take in the world and come to open-ended decisions. In fact, it is not clear how much the conscious you—as opposed to the genetic and neural you—gets to do any deciding at all.

Tourette’s syndrome,

The crux of the question is whether all of your actions are fundamentally on autopilot or whether there is some little bit that is “free” to choose, independent of the rules of biology. This has always been the sticking point for both philosophers and scientists. As far as we can tell, all activity in the brain is driven by other activity in the brain, in a vastly complex, interconnected network. For better or worse, this seems to leave no room for anything other than neural activity—that is, no room for a ghost in the machine. To consider this from the other direction, if free will is to have any effect on the actions of the body, it needs to influence the ongoing brain activity. And to do that, it needs to be physically connected to at least some of the neurons. But we don’t find any spot in the brain that is not itself driven by other parts of the network. Instead, every part of the brain is densely interconnected with—and driven by—other brain parts. And that suggests that no part is independent and therefore “free.”

So in our current understanding of science, we can’t find the physical gap in which to slip free will—the uncaused causer—because there seems to be no part of the machinery that does not follow in a causal relationship from the other parts. Everything stated here is predicated on what we know at this moment in history, which will certainly look crude a millennium from now; however, at this point, no one can see a clear way around the problem of a nonphysical entity (free will) interacting with a physical entity (the stuff of the brain).

Libet discovered that people became aware of an urge to move about a quarter of a second before they actually made the move. But that wasn’t the surprising part. He examined their EEG recordings—the brain waves—and found something more surprising: the activity in their brains began to rise before they felt the urge to move. And not just by a little bit. By over a second. (See figure on the following page.) In other words, parts of the brain were making decisions well before the person consciously experienced the urge.14 Returning to the newspaper analogy of consciousness, it seems that our brains crank away behind the scenes—developing neural coalitions, planning actions, voting on plans—before we receive the news that we’ve just had the great idea to lift a finger. Libet’s experiments caused a commotion.15 Could

veto power.

principle of sufficient automatism.

Although we know that there is a strong relationship between brain and behavior, neuroimaging remains a crude technology, unable to meaningfully weigh in on assessments of guilt or innocence, especially on an individual basis. Imaging methods make use of highly processed blood-flow signals, which cover tens of cubic millimeters of brain tissue. In a single cubic millimeter of brain tissue, there are some one hundred million synaptic connections between neurons. So modern neuroimaging is like asking an astronaut in the space shuttle to look out the window and judge how America is doing. He can spot giant forest fires, or a plume of volcanic activity billowing from Mount Rainier, or the consequences of broken New Orleans levies—but from his vantage point he is unable to detect whether a crash of the stock market has led to widespread depression and suicide, whether racial tensions have sparked rioting, or whether the population has been stricken with influenza. The astronaut doesn’t have the resolution to discern those details, and neither does the modern neuroscientist have the resolution to make detailed statements about the health of the brain. He can say nothing about the minutiae of the microcircuitry, nor the algorithms that run on the vast seas of millisecond-scale electrical and chemical signaling.

It cannot make sense for culpability to be determined by the limits of current technology. A legal system that declares a person culpable at the beginning of a decade and not culpable at the end is not one in which culpability carries a clear meaning. * * * The heart of the problem is that it no longer makes sense to ask, “To what extent was it his biology and to what extent was it him?” The question no longer makes sense because we now understand those to be the same thing. There is no meaningful distinction between his biology and his decision making. They are inseparable.

There is no meaningful distinction between his biology and his decision making. They are inseparable.

“As long as we can’t identify all the causes, which we cannot and will probably never be able to do, we should grant that for everybody there is a neurobiological reason for being abnormal.”

The bottom line of the argument is that criminals should always be treated as incapable of having acted otherwise.

The criminal activity itself should be taken as evidence of brain abnormality, regardless whether currently measurable problems can be pinpointed. This means that the burden on neuroscientific expert witnesses should be left out of the loop:

all we ultimately want to know is how a person is likely to behave in the future.

And really, that’s all maturation is. The main difference between teenage and adult brains is the development of the frontal lobes. The human prefrontal cortex does not fully develop until the early twenties, and this underlies the impulsive behavior of teenagers. The frontal lobes are sometimes called the organ of socialization, because becoming socialized is nothing but developing circuitry to squelch our basest impulses.

After training at the prefrontal gym, you might still crave the chocolate cake, but you’ll know how to win over the craving instead of letting it win over you. It’s not that we don’t want to enjoy our impulsive thoughts (Mmm, cake), it’s merely that we want to endow the frontal cortex with some control over whether we act upon them (I’ll pass). Similarly, if a person considers committing a criminal act, that’s permissible as long as he doesn’t take action. For the pedophile, we cannot hope to control whether he is attracted to children. As long as he never acts on it, that may be the best we can hope for as a society that respects individual rights and freedom of thought. We cannot restrict what people think; nor should a legal system hope to set that as its goal. Social policy can only hope to prevent impulsive thoughts from tipping into behavior until they are reflected upon by a healthy

neurodemocracy.

After Galileo discovered the moons of Jupiter in his homemade telescope in 1610, religious critics decried his new sun-centered theory as a dethronement of man. They didn’t suspect that this was only the first dethronement of several. One hundred years later, the study of sedimentary layers by the Scottish farmer James Hutton toppled the Church’s estimate of the age of the Earth—making it eight hundred thousand times older. Not long afterward, Charles Darwin relegated humans to just another branch in the swarming animal kingdom. At the beginning of the 1900s, quantum mechanics irreparably altered our notion of the fabric of reality. In 1953, Francis Crick and James Watson deciphered the structure of DNA, replacing the mysterious ghost of life with something that we can write down in sequences of four letters and store in a computer.