A Whole New Mind Page 2
My first task is simple. They display on the screen a black-and-white photo of a face fixed in an extreme expression. (A woman who looks as if Yao Ming just stepped on her toe. Or a fellow who apparently has just remembered that he left home without putting on pants.) Then they remove that face, and flash on the screen two photos of a different person. Using the buttons on my clicker, I’m supposed to indicate which of those two faces expresses the same emotion as the initial face.
For example, the researchers show me this face:
Then they remove it and show me these two faces:
I click the button on the right because the face on the right expresses the same emotion as the earlier face. The task, if you’ll pardon the expression, is a no-brainer.
When the facial matching exercise is over, we move to another test of perception. The researchers show me forty-eight color photos, one after another, in the manner of a slide show. I click the appropriate button to indicate whether the scene takes place indoors or outdoors. These photos occupy two extremes. Some are bizarre and disturbing; others are banal and inoffensive. The photos include a coffee mug sitting on a counter, several people brandishing guns, a toilet overflowing with waste, a lamp, and a few explosions.
For instance, the researchers display an image like this:*
So I click the button that indicates that this scene takes place inside. The task requires that I concentrate, but I don’t much strain. The exercise feels about the same as the previous one.
What happens inside my brain, however, tells a different story. When the brain scans appear on the computers, they show that when I looked at the grim facial expressions, the right side of my brain sprang into action and enlisted other parts of that hemisphere. When I looked at the scary scenes, my brain instead called in greater support from the left hemisphere.1 Of course, parts of both sides worked on each task. And I felt precisely the same during each exercise. But the fMRI clearly showed that for faces, my right hemisphere responded more than my left—and for gun-wielding bad guys and similar predicaments, my left hemisphere took the lead.
Why?
The Right (and Left) Stuff
Our brains are extraordinary. The typical brain consists of some 100 billion cells, each of which connects and communicates with up to 10,000 of its colleagues. Together they forge an elaborate network of some one quadrillion (1,000,000,000,000,000) connections that guides how we talk, eat, breathe, and move. James Watson, who won the Nobel Prize for helping discover DNA, described the human brain as “the most complex thing we have yet discovered in our universe.”2 (Woody Allen, meanwhile, called it “my second favorite organ.”)
Yet for all the brain’s complexity, its broad topography is simple and symmetrical. Scientists have long known that a neurological Mason-Dixon Line divides the brain into two regions. And until surprisingly recently, the scientific establishment considered the two regions separate but unequal. The left side, the theory went, was the crucial half, the half that made us human. The right side was subsidiary—the remnant, some argued, of an earlier stage of development. The left hemisphere was rational, analytic, and logical—everything we expect in a brain. The right hemisphere was mute, nonlinear, and instinctive—a vestige that nature had designed for a purpose that humans had outgrown.
As far back as the age of Hippocrates, physicians believed that the left side, the same side that housed the heart, was the essential half. And by the 1800s, scientists began to accumulate evidence to support that view. In the 1860s, French neurologist Paul Broca discovered that a portion of the left hemisphere controlled the ability to speak language. A decade later, a German neurologist named Carl Wernicke made a similar discovery about the ability to understand language. These discoveries helped produce a convenient and compelling syllogism. Language is what separates man from beast. Language resides on the left side of the brain. Therefore the left side of the brain is what makes us human.
This view prevailed for much of the next century—until a soft-spoken Caltech professor named Roger W. Sperry reshaped our understanding of our brains and ourselves. In the 1950s, Sperry studied patients who had epileptic seizures that had required removal of the corpus callosum, the thick bundle of some 300 million nerve fibers that connects the brain’s two hemispheres. In a set of experiments on these “split-brain” patients, Sperry discovered that the established view was flawed. Yes, our brains were divided into two halves. But as he put it, “The so-called subordinate or minor hemisphere, which we had formerly supposed to be illiterate and mentally retarded and thought by some authorities to not even be conscious, was found to be in fact the superior cerebral member when it came to performing certain kinds of mental tasks.” In other words, the right wasn’t inferior to the left. It was just different. “There appear to be two modes of thinking,” Sperry wrote, “represented rather separately in the left and right hemispheres, respectively.” The left hemisphere reasoned sequentially, excelled at analysis, and handled words. The right hemisphere reasoned holistically, recognized patterns, and interpreted emotions and nonverbal expressions. Human beings were literally of two minds.
This research helped earn Sperry a Nobel Prize in medicine, and forever altered the fields of psychology and neuroscience. When Sperry died in 1994, The New York Times memorialized him as the man who “overturned the prevailing orthodoxy that the left hemisphere was the dominant part of the brain.” He was the rare scientist, said the Times, whose “experiments passed into folklore.”3
Sperry, though, had some help transporting his ideas from the laboratory to the living room—in particular, a California State University art instructor named Betty Edwards. In 1979, Edwards published a wonderful book titled Drawing on the Right Side of the Brain. Edwards rejected the notion that some people just aren’t artistic. “Drawing is not really very difficult,” she said. “Seeing is the problem.”4 And the secret to seeing—really seeing—was quieting the bossy know-it-all left brain so the mellower right brain could do its magic. Although some accused Edwards of oversimplifying the science, her book became a bestseller and a staple of art classes. (We’ll learn about Edwards’s techniques in Chapter 6.)
Thanks to Sperry’s pioneering research, Edwards’s skillful popularization, and the advent of technologies like the fMRI that allow researchers to watch the brain in action, the right hemisphere today has achieved a measure of legitimacy. It’s real. It’s important. It helps make us human. No neuroscientist worth her PhD ever disputes that. Yet beyond the neuroscience labs and brain-imaging clinics, two misconceptions about the right side of the brain persist.
The Wrong Stuff
These two misconceptions are opposite in spirit but similar in silliness. The first considers the right brain a savior; the second considers it a saboteur.
Adherents of the savior view have climbed aboard the scientific evidence on the right hemisphere and raced from legitimacy to reverence. They believe that the right brain is the repository of all that is good and just and noble in the human condition. As neuroscientist Robert Ornstein puts it in The Right Mind, one of the better books on this subject:
Many popular writers have written that the right hemisphere is the key to expanding human thought, surviving trauma, healing autism, and more. It’s going to save us. It’s the seat of creativity, of the soul, and even great casserole ideas.5
Oh, my. Over the years, peddlers of the savior theory have tried to convince us of the virtues of right-brain cooking and right-brain dieting, right-brain investing and right-brain accounting, right-brain jogging and right-brain horseback riding—not to mention right-brain numerology, right-brain astrology, and right-brain lovemaking, the last of which may well lead to babies who’ll eventually achieve greatness by eating right-brain breakfast cereal, playing with right-brain blocks, and watching right-brain videos. These books, products, and seminars often contain a valid nugget or two—but in general they are positively foolish. Even worse, this cascade of baseless, New Age gobbledygook has often served to de
grade, rather than enhance, public understanding of the right hemisphere’s singular outlook.
Partly in response to the tide of inane things that have been said about the right brain, a second, contrary bias has also taken hold. This view grudgingly acknowledges the right hemisphere’s legitimacy, but believes that emphasizing so-called right-brain thinking risks sabotaging the economic and social progress we’ve made by applying the force of logic to our lives. All that stuff that the right hemisphere does—interpreting emotional content, intuiting answers, perceiving things holistically—is lovely. But it’s a side dish to the main course of true intelligence. What distinguishes us from other animals is our ability to reason analytically. We are humans, hear us calculate. That’s what makes us unique. Anything else isn’t simply different; it’s less. And paying too much attention to those artsyfartsy, touchy-feely elements will eventually dumb us down and screw us up. “What it comes down to,” Sperry said shortly before he died, “is that modern society [still] discriminates against the right hemisphere.” Within the saboteur position is the residual belief that although the right side of our brains is real, it’s still somehow inferior.
Alas, the right hemisphere will neither save us nor sabotage us. The reality, as is so often the case with reality, is more nuanced.
The Real Stuff
The two hemispheres of our brains don’t operate as on-off switches—one powering down as soon as the other starts lighting up. Both halves play a role in nearly everything we do. “We can say that certain regions of the brain are more active than others when it comes to certain functions,” explains one medical primer, “but we can’t say those functions are confined to particular areas.”6 Still, neuroscientists agree that the two hemispheres take significantly different approaches to guiding our actions, understanding the world, and reacting to events. (And those differences, it turns out, offer considerable guidance for piloting our personal and professional lives.) With more than three decades of research on the brain’s hemispheres, it’s possible to distill the findings to four key differences.
1. The left hemisphere controls the right side of the body;
the right hemisphere controls the left side of the body.
Raise your right hand. Seriously, if you can, hold your right hand high in the air. Your left hemisphere (or, more accurately, a region of your left hemisphere) did that. Now, if you’re able, tap your left foot. A region of your right hemisphere did that. Our brains are “contralateral”—that is, each half of the brain controls the opposite half of the body. That’s why a stroke on the right side of someone’s brain will make it difficult for that person to move the left side of her body and a stroke on the left side will impair the functioning of the right. Since roughly 90 percent of the population is right-handed, that means that in roughly 90 percent of the population, the left hemisphere is controlling important movements such as handwriting, eating, and maneuvering a computer mouse.
Contralateralization comes into play, not only when we sign our name or kick a ball, but also when we move our heads and our eyes. Here’s another exercise. Turn your head slowly to the left. Once again, the opposite hemisphere—the right side of your brain—largely guided that maneuver. Now turn your head slowly to the right. This time, the left hemisphere did the steering. Now, using whichever part of your brain you’d like, think of an activity that involves the latter movement—that is, slowly moving your head and eyes from left to right. Here’s a hint: you’re doing it now. In Western languages, reading and writing involve turning from left to right, and therefore exercise the brain’s left hemisphere. Written language, invented by the Greeks around 550 B.C.E., has helped reinforce left hemisphere dominance (at least in the West) and created what Harvard classicist Eric Havelock called “the alphabetic mind.”7 So perhaps it’s no surprise, then, that the left hemisphere has dominated the game. It’s the only side that knows how to write the rules.
2. The left hemisphere is sequential;
the right hemisphere is simultaneous.
Consider another dimension of the alphabetic mind: it processes sounds and symbols in sequence. When you read this sentence, you begin with the “when,” move to the “you,” and decode every letter, every syllable, every word in progression. This, too, is an ability at which your brain’s left hemisphere excels. In the sequential words of one neuroscience textbook:
[T]he left hemisphere [is] particularly good at recognizingserial events—events whose elements occur one after the other—and controlling sequences of behavior. The left hemisphere is also involved in controlling serial behaviors. The serial functions performed by the left hemisphere include verbal activities, such as talking, understanding the speech of other people, reading, and writing.8
By contrast, the right hemisphere doesn’t march in the single-file formation of A-B-C-D-E. Its special talent is the ability to interpret things simultaneously. This side of our brains is “specialized in seeing many things at once: in seeing all the parts of a geometric shape and grasping its form, or in seeing all the elements of a situation and understanding what they mean.”9 This makes the right hemisphere particularly useful in interpreting faces. And it confers on human beings a comparative advantage over computers. For instance, the iMac computer on which I’m typing this sentence can perform a million calculations per second, far more than the fastest left hemisphere on the planet. But even the most powerful computers in the world can’t recognize a face with anywhere close to the speed and accuracy of my toddler son. Think of the sequential/simultaneous difference like this: the right hemisphere is the picture; the left hemisphere is the thousand words.
3. The left hemisphere specializes in text;
the right hemisphere specializes in context.
In most people, language originates in the left hemisphere. (This is true of about 95 percent of right-handers and 70 percent of left-handers. In the rest—about 8 percent of the population—the division of linguistic labor is more complicated.) But the right hemisphere doesn’t cede full responsibility to the left. Instead, the two sides carry out complementary functions.
Suppose that one night you and your spouse are preparing dinner. Suppose, too, that midway through the preparations, your spouse discovers that you forgot to buy the dinner’s most important ingredient. Suppose then that your spouse grabs the car keys, curls a lip, glares at you, and hisses, “I’m going to the store.” Nearly everyone with an intact brain would understand two things about the words just uttered. First, your spouse is heading to Safeway. Second, your spouse is pissed. Your left hemisphere figured out the first part—that is, it deciphered the sounds and syntax of your spouse’s words and arrived at their literal meaning. But your right hemisphere understood the second aspect of this exchange—that the ordinarily neutral words “I’m going to the store” weren’t neutral at all. The glare of the eyes and the hiss of the voice signal that your spouse is angry.
Individuals with damage to one hemisphere can’t reach this dual conclusion. A person with an impaired right hemisphere, and thus only a functioning left hemisphere, would hear such comments and understand that the spouse is driving to the store—but would remain oblivious to the anger and annoyance fueling the trip. A person with an impaired left hemisphere, and thus only a functioning right hemisphere, would understand that the spouse is miffed—but might not know where the spouse just went.
This distinction applies not only to understanding language but also to speaking it. Patients with damage to certain regions of their right hemisphere can talk coherently—abiding the rules of grammar and deploying a standard vocabulary. But as British psychologist Chris McManus notes in his prizewinning book Right Hand Left Hand:
Their language . . . is not normal, lacking the musical quality of speech, prosody, whereby the tone goes up and down, and the words accelerate and decelerate or get louder and softer, providing emotion and emphasis. Speech without prosody is like those computer-synthesized voices one hears on telephones.10
To o
versimplify just a bit, the left hemisphere handles what is said; the right hemisphere focuses on how it’s said—the nonverbal, often emotional cues delivered through gaze, facial expression, and intonation.
But the distinction between left and right comprises more than the difference between verbal and nonverbal. The text/context distinction, originally put forward by Robert Ornstein, applies more broadly. For instance, certain written languages depend heavily on context. Languages such as Arabic and Hebrew are often written only in consonants, which means the reader must figure out what the vowel is by the surrounding concepts and ideas. In those languages, if you read the equivalent of “stmp n th bg,” you’d fill in different vowels depending on whether the phrase appeared in a pest control manual (“stomp on the bug”) or a short story about a trip to the post office (“stamp in the bag”). Unlike English, languages that require the reader to supply the vowels by discerning the context are usually written from right to left.11 And as we learned a few pages ago, moving one’s eyes in that direction depends on the brain’s right hemisphere.
Context is also important in other dimensions of language. For example, many studies have shown that the right hemisphere is responsible for our ability to comprehend metaphors. If you tell me that José has “a heart the size of Montana,” my left hemisphere quickly assesses who José is, what a heart is, and how big Montana is. But when the literal meaning of the sentence doesn’t compute—how can a 147,000-square-mile heart fit inside José’s modest chest cavity?—it calls in the right hemisphere to resolve the incongruity. The right hemisphere explains to the left that José doesn’t have some bizarre cardiac condition but instead is a generous and loving person. “Neither side of the brain . . . can do the job without the other,” Ornstein writes. “We need the text of our lives to be in context.”12