In the final chapter of his latest book, Incognito: The Secret Lives of the Brain, neuroscientist David Eagleman muses on the ultimate dethronement of humankind, the “fall from the center of ourselves.” Just as Galileo plucked the Earth from the center of the solar system, and Darwin relegated us to one twig among many on the evolutionary tree, a century of modern neuroscience has confirmed Freud’s intuition that the vast majority of brain activity occurs at levels of which the conscious “I” is scarcely even aware—much less in control of. What we call the conscious mind, Eagleman argues, is far from center stage, and the more we try to find out who—or what—is actually in control of our brain, the more we find out there is, as Gertrude Stein said, “no there there.”
Before he considers the broader implications of our fall from grace, Eagleman spends the first half of the book revealing—through experiments, anecdotes, puzzles, optical illusions, and current events—the extent of the neural wizardry operating behind the conscious curtain of the “I.” It is this wizardry, he suggests, that constructs the cognitive illusion we confidently declare reality. Eagleman, director of the Laboratory for Perception and Action at Baylor College of Medicine, is an agile guide; he is someone who cares about the craft of writing. His bestselling work of fiction, Sum: Forty Tales from the Afterlives, a series of imaginative (if somewhat gimmicky) thought experiments about the possible nature(s) of God, was widely praised when it appeared in 2009. In his latest book, he proves himself, once again. Eagleman presents difficult neuroscience concepts in an energetic, casual voice with plenty of analogies and examples to ensure that what could easily be an overwhelming catalog of facts remains engaging and accessible.
Eagleman uses everyday experiences, familiar to each of us, which reveal the hidden machinations of the brain working in unexpected ways. Even an intuitively effortless act such as seeing, he shows us, is not a passive process of observation, but rather the product of a vast subsurface machinery (by some measures, nearly one-third of the human brain is devoted to vision) that uses an arsenal of assumptions to interpret the ambiguous barrage of shapes and colors that constitute any visual scene. Most readers will fail to appreciate any of these processes until we are shown how often—and how profoundly—we get it totally wrong. For example, the resolution of our peripheral vision is so shockingly poor that if you ask a friend to hold a handful of colored highlighters out to his side while you stare at his nose, you may have the vague sensation of a rainbow in the distance, but might be surprised to discover that you’re unable to name or order any of the colors. Since the brain constantly darts our eyes around so that the high-resolution central vision focuses on whatever it is we are interested in—and therefore anything we are paying attention to appears in sharp focus—the brain assumes the entire visual world is in focus. We think we see what we do not.
What optical illusions really point out is that all of vision is, in a sense, an illusion.
One striking optical illusion, in which a dot on the page disappears as you slowly move the book away from your face, demonstrates that a huge region of vision is in fact missing—due to a quirk of anatomy, we have a sizable blind spot. And yet, no one noticed this blind spot until its chance discovery in the 17th century because the brain fills in the missing information. It is constantly inventing a patch of reality. The lesson of examples such as these, Eagleman points out, is that “you’re not perceiving what’s out there. You are perceiving whatever your brain tells you.” Whether you are in control of your eyes or your eyes are in control of you is the central, unsettling question posed by these chapters.
The extent to which forces that elude introspection influence not only your perceptions but also your behavior is detailed with increasingly bizarre examples. We find out that a stripper earns higher tips when she is at the most fertile point in her menstrual cycle. People are more likely to marry other people whose names begin with the same letter as their own. Those who are born on February 2nd (2/2) are statistically more likely to live in places like Twin Lakes, Wisconsin; those born on March 3rd in Three Forks, Montana; and those born on June 6th in Six Mile, South Carolina. What these interesting but difficult-to-interpret quirks of human nature reveal is that choices which you happily assign to volition—to free will—may in fact be determined by the alien logic of brain processes inaccessible to the conscious “I.”
But does any of this this matter? Is anything in your life going to change if modern neuroscience strips you of the illusion of free will? Isn’t it just fine to go through the course of the day believing what you see, or ignoring the possibility that arbitrary numbers might influence where you choose to live? Unless you are a philosopher, these issues might seem irrelevant, but Eagleman’s book serves as a clarion call to institutions of law and policy, arguing that they need to be based upon a deeper understanding of ourselves.
As director of the Initiative on Neuroscience and the Law at Baylor University, Eagleman has a thoughtful and considered take on issues of cultural and political power, and his chapter on neuroscience and the law proves to be the strongest in the book. While today’s courts rarely allow such technologies as brain scans into the courtroom, judges may soon deem such scans relevant to arguments about a defendant’s mental state. Many detractors worry moving blame to biology will result in dangerous criminals being exculpated—the “It wasn’t me, it was my brain” defense. Yet the shift is already in motion outside of the courtroom. Most of us believe that diseases such as depression, schizophrenia, and epilepsy have a neurological basis, and that factors such as genes make some of us more susceptible to risky behavioral patterns, such as drug addiction. Similarly, most of us intuitively feel that an Alzheimer’s patient that shoplifts is somehow less guilty of the crime, or that a mentally disabled person who murders should not be sent to prison. How is a legal system that rests on volition and culpability going to address this shifting locus of responsibility?
Eagleman attacks the question head-on:
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.
He seeks not to revise the definition of blameworthiness but to remove the concept from jurisprudence altogether. It is true that the more we understand about brain circuitry, the more concepts like indulgence, discipline, and motivation can be explained by biology. It’s also true that if there is a measurable brain problem—such as the case in which a man committed murders due to neurological changes brought on by a brain tumor—the defendant is viewed as less blameworthy. However, a system of jurisprudence in which blame is based upon the state of current technology is not on stable footing; rather than adjusting the definition of blame to suit shifting technology, perhaps we should eschew blame altogether. “Blameworthiness,” Eagleman writes, “is a backward-looking concept that demands the impossible task of untangling the hopelessly complex web of genetics and environment that constructs the trajectory of a human life.” Instead, he hopes that we can leverage findings in neuroscience to better structure the way we punish, ultimately replacing the notion of retribution with either rehabilitation when possible or humane incapacitation when not.
Almost all of the ideas in Eagleman’s book are well-articulated and entertaining, elucidated with the intelligent, casual tone of an enthusiastic university lecturer. However, it’s important to note that, like a lecture, Eagleman’s book does not constitute—nor claim to constitute—original thinking. He has curated examples from the world of modern neuroscience in support of ideas already explored by writers such as Daniel Dennett and Douglas Hoftstadter, or biologists such as Gerald Edelman, packaging them into a highly accessible and energetic work of popular science. Eagleman’s book is rooted firmly in the tradition of scientist-as-explainer, along the lines of Brian Greene’s efforts to bring string theory to a lay audience in The Elegant Universe, or Daniel Levitin’s elucidation of the neuroscience of music in This Is Your Brain On Music.
While we are left, at the end of the book, with the disturbing sensation of wondering who, exactly, it is we are looking at when we look in the mirror, Eagleman assures us that this latest act of dethronement does not leave us disconsolately adrift. Just as astronomy’s revolution invited us to contemplate the gorgeous, vast expanses of the universe, a better understanding of the human brain “tends to open up something bigger than us, ideas more wonderful than we had originally imagined.” Neuroscience can’t weigh in yet on whether or not we house an extrabiological soul, but even if how mind emerges from brain is one day completely described by the laws of classical physics, the threads of causality will be so tangled as to only offer partial insight. So while it is disquieting to ponder the fact that the conscious mind, unaware of the incomprehensible dynamics of multiple neural subsystems blithely chugging away, may be left merely to superimpose meaning on our actions and choices, there is indeed beauty and comfort in knowing that we contain the unknowable.