SPLITTING THE BRAIN
In 1962, the storytelling mind was inadvertently isolated—if not discovered—when a neurosurgeon named Joseph Bogen persuaded a severely epileptic patient to undergo a dangerous experimental procedure. Bogen drilled small holes through the top of the patient’s skull, introduced a specialized saw into one of the holes, and used it to open a “bone flap” in the cranium. Using scissors, Bogen cut through the brain’s protective leathery covering, the dura. Then he gingerly pried apart the two lobes of the patient’s brain until he could see the corpus callosum, the nervy band of fibers that routes information back and forth between the left and right hemispheres. Like a saboteur knocking out communication lines, Bogen introduced a scalpel and severed the corpus callosum. In effect, he split the brain—the left and right hemispheres could no longer communicate. Then he reconnected the bone flap with tiny screws, stitched up the patient’s scalp, and waited to see what would happen.
Bogen was no mad scientist. The operation was dangerous and its outcome uncertain. But Bogen’s patient, a former paratrooper, was dealing with life-threatening seizures that were unresponsive to standard treatments. Bogen believed that severing the corpus callosum might control the seizures. Animal studies suggested it might, and Bogen knew of human cases where seizures had abated after tumors or injuries harmed the corpus callosum.
Perhaps surprisingly, Bogen’s surgical Hail Mary pass was a success. Although his epileptic patient still experienced seizures, their frequency and severity were greatly diminished. And even more surprisingly, there seemed to be no side effects. The split-brained man reported no differences in any of his mental processes.
In the days before fMRI machines and other advanced methods of brain imaging, split-brain patients were a boon to neuroscience. Thanks largely to these patients, scientists were able to isolate and study the workings of the two hemispheres of the brain. They discovered that the left brain is specialized for tasks such as speaking, thinking, and generating hypotheses. The right brain is incapable of speech or serious cognitive work; its jobs include recognizing faces, focusing attention, and controlling visual-motor tasks.
The leading pioneer of split-brain neuroscience is Michael Gazzaniga. In his research, Gazzaniga and his collaborators have identified specialized circuitry in the left hemisphere that is responsible for making sense of the torrent of information that the brain is always receiving from the environment. The job of this set of neural circuits is to detect order and meaning in that flow, and to organize it into a coherent account of a person’s experience—into a story, in other words. Gazzaniga named this brain structure “the interpreter.”
Because of the quirky wiring of the brain, visual information that enters the right eye is fed to the left brain, and information entering the left eye goes to the right brain. In an intact brain, visual information that goes to the left brain is then piped via the corpus callosum to the right brain. But in split-brain individuals, information that enters only one eye gets marooned in the opposite hemisphere, leaving the other hemisphere in the dark.
In a brilliant series of experiments, Gazzaniga and his colleagues had split-brain subjects stare at a dot in the center of a computer screen. They then flashed images to the right and left of the dot. Images flashed to the left of the dot were piped only to the right brain, while images that appeared to the right of the dot were sent only to the left brain.
In one experiment, Gazzaniga and his colleagues showed a chicken claw to a split-brain subject’s left brain and a snowy scene to his right brain. They then asked the subject to select from an array of pictures lined up in front of him. Again, due to the odd way the brain is wired, the right side of the human body is predominantly controlled by the left brain and the left side by the right brain. With the right hand, the subject chose a picture of a chicken (because the side of the brain that controls that hand had seen a chicken claw). With the left hand, the subject chose a picture of a snow shovel (because the side of the brain controlling that hand had seen a snowy scene).
The split-brain subject was then asked why he chose those two images. The first part of the subject’s response made perfect sense: “I chose the chicken, because you showed me a picture of a chicken foot.” The subject was able to respond correctly because the image of the chicken claw had been fed to the left hemisphere, which is the verbal side of the brain. But the right side of the brain is mute. So when the subject was asked, “Why did you choose the shovel?” he was not able to give the correct response: “Because you showed me a picture of a snowy scene.”
All of this zigzagging from right to left might be a little confusing. But bear with me—the underlying point is simple. The side of the subject’s brain responsible for communicating with the researchers (the left) had no idea that the right side of the brain had received an image of a snowy scene. All the speaking side of the brain knew was that the left hand (controlled by the right brain) had reached out and chosen a picture of a snowy scene. It had no idea why. Nonetheless, when the researchers asked, “Why did you choose the shovel?” the subject had a ready and confident response: “Because you need a shovel to clean out the chicken coop.”
Gazzaniga and his colleagues varied these studies in all sorts of clever ways. When they fed a split-brain subject’s right hemisphere a funny image, the subject would laugh. A researcher would then ask, “Why are you laughing?” The subject’s left brain, which was responsible for answering the question, had absolutely no idea. It was not in on the joke. But that didn’t stop the left brain from inventing an explanation. The subject might claim that he had just remembered a funny incident. In another study, a subject’s right brain was flashed an image of the word “walk.” The subject stood up obediently and started walking across the room. When a researcher asked where the man was going, he spontaneously fabricated—and believed—a story about being thirsty and wanting a Coke.
These are representative examples of a pattern Gazzaniga and his colleagues exposed again and again in split-brain subjects. The left brain is a classic know-it-all; when it doesn’t know the answer to a question, it can’t bear to admit it. The left brain is a relentless explainer, and it would rather fabricate a story than leave something unexplained. Even in split-brain subjects, who are working with one-half of their brains tied behind their backs, these fabrications are so cunning that they are hard to detect except under laboratory conditions.
If Gazzaniga’s research just applied to the few dozen epileptics who have undergone split-brain surgery, it would be of limited interest. But this research has important implications for how we understand ordinary, intact brains. The storytelling mind is not created when the scalpel cuts into the corpus callosum. Splitting the brain just pins it down for study.
SHERLOCK HOLMES SYNDROME
You can think of your own storytelling mind as a homunculus (a tiny man) who dwells perhaps an inch or two above and behind your left eye. The little man has a lot in common with Sherlock Holmes, the great literary patriarch who paved the way for a thousand fictional detectives, including the forensic whizzes of hit television shows such as CSI. In Sir Arthur Conan Doyle’s portrait, Holmes is a genius of criminal investigation, a Newton of the new science of criminology. Holmes has a spooky ability to look at a certain outcome—a corpse, a smattering of clues—and see the whole rich story that led up to it: a love affair, poison pills, adventures in the American West with Brigham Young and the Mormons.
These details come from the first Sherlock Holmes novel, A Study in Scarlet (1887). The novel begins by introducing the narrator, (“my dear”) Watson—who is not so much a character as a literary device—whose job it is to highlight Holmes’s brilliance through his own conventionality. Watson first meets Holmes in a smoky chemistry lab, where the genius is perfecting new forensic techniques. Holmes—tall, lithe, haughty—turns to Watson and shakes his hand. And then, for the first of a thousand times, the wizard blows Watson’s mind. He says, “You have been in Afghanistan, I percei
ve.”
Illustration from the 1906 edition of Sir Arthur Conan Doyle’s A Study in Scarlet.
Watson is dumbstruck. How could Holmes have known? Later, when Holmes and Watson are lounging in their bachelor pad, Holmes explains that there was no magic in his insight, only logic. With great relish, he tells Watson how he “reasoned backwards” from the silent details of his appearance to make rational inferences about Watson’s life. “The train of reasoning,” Holmes says, ran like this:
Here is a gentleman of a medical type, but with the air of a military man. Clearly an army doctor, then. He has just come from the tropics, for his face is dark, and that is not the natural tint of his skin, for his wrists are fair. He has undergone hardship and sickness, as his haggard face says clearly. His left arm has been injured. He holds it in a stiff and unnatural manner. Where in the tropics could an English army doctor have seen much hardship and got his arm wounded? Clearly in Afghanistan.
Whenever Holmes tells Watson such tales, Watson shakes his head in amazement. And we, Doyle’s readers, are supposed to take our cue from Watson, thrilling to the detective’s genius. But while Sherlock Holmes stories are good fun, it pays to notice that Holmes’s method is ridiculous.
Take the rich story Holmes concocts after glancing at Watson in the lab. Watson is dressed in ordinary civilian clothes. What gives him “the air of a military man”? Watson is not carrying his medical bag or wearing a stethoscope around his neck. What identifies him as “a gentleman of a medical type”? And why is Holmes so sure that Watson had just returned from Afghanistan rather than from one of many other dangerous tropical garrisons where Britain, at the height of its empire, stationed troops? (Let’s ignore the fact that Afghanistan is not actually in the tropical band.) And why does Holmes jump to the conclusion that Watson has sustained a battle wound? Watson holds his arm stiffly, but how does Holmes know that this isn’t a result of a cricket injury? How does he know that Watson isn’t experiencing—in his painful left arm—a classic symptom of a heart attack?
In short, Sherlock Holmes’s usual method is to fabricate the most confident and complete explanatory stories from the most ambiguous clues. Holmes seizes on one of a hundred different interpretations of a clue and arbitrarily insists that the interpretation is correct. This then becomes the basis for a multitude of similarly improbable interpretations that all add up to a neat, ingenious, and vanishingly improbable explanatory story.
Sherlock Holmes is a literary figment. He lives in Neverland, so he always gets to be right. But if he tried to ply his trade as a “consulting detective” in the real world, he would be a dangerously incompetent boob—more like The Pink Panther’s Inspector Clouseau than the genius who lives with his friend Watson at 221b Baker Street.
We each have a little Sherlock Holmes in our brain. His job is to “reason backwards” from what we can observe in the present and show what orderly series of causes led to particular effects. Evolution has given us an “inner Holmes” because the world really is full of stories (intrigues, plots, alliances, relationships of cause and effect), and it pays to detect them. The storytelling mind is a crucial evolutionary adaptation. It allows us to experience our lives as coherent, orderly, and meaningful. It is what makes life more than a blooming, buzzing confusion.
But the storytelling mind is imperfect. After almost five decades of studying the tale-spinning homunculus who resides in the left brain, Michael Gazzaniga has concluded that this little man—for all of his undeniable virtues—can also be a bumbler. The storytelling mind is allergic to uncertainty, randomness, and coincidence. It is addicted to meaning. If the storytelling mind cannot find meaningful patterns in the world, it will try to impose them. In short, the storytelling mind is a factory that churns out true stories when it can, but will manufacture lies when it can’t.
GEOMETRIC RAPE
The human mind is tuned to detect patterns, and it is biased toward false positives rather than false negatives. The same mental software that makes us very alert to human faces and figures causes us to see animals in clouds or Jesus in griddle marks. According to psychologists, this is part of a “mind design” that helps us perceive meaningful patterns in our environments.
Image of a “face” on Mars taken by Viking 1 in 1976. While some seized on the face as evidence of a Martian civilization, higher-resolution images showed that the “face” is just an ordinary Martian hill.
Our hunger for meaningful patterns translates into a hunger for story. As the video game designer and writer James Wallis puts it, “Human beings like stories. Our brains have a natural affinity not only for enjoying narratives and learning from them but also for creating them. In the same way that your mind sees an abstract pattern and resolves it into a face, your imagination sees a pattern of events and resolves it into a story.” There are a lot of neat studies that make Wallis’s point, showing how we automatically extract stories from the information we receive, and how—if there is no story there—we are only too happy to invent one. Consider the following information:
Todd rushed to the store for flowers.
Greg walked her dog.
Sally stayed in bed all day.
Quick, what were you thinking? If you are like most people, you were puzzling over the three sentences, trying to find the hidden story. Perhaps Sally is sad because someone has died. Perhaps Greg and Todd are her friends: one is seeing to Sally’s dog, and the other is buying her flowers. Or perhaps Sally is happy. She has just won the lottery, and to celebrate she has decided to luxuriate in bed all day. Greg and Todd are the underwear models she has hired as her masseurs and personal assistants.
In fact, these sentences are unrelated. I made them up. But if you have a healthy storytelling mind, you will automatically start to weave them together into the beginnings of a story. Of course, we recognize consciously that these sentences could serve as building blocks for an infinite number of narratives. But studies show that if you give people random, unpatterned information, they have a very limited ability not to weave it into a story.
This point is beautifully illustrated in an experiment by psychologists Fritz Heider and Marianne Simmel. In the mid-1940s, the researchers made a short animated film. The film is very simple. There is a big square that is motionless, except for a flap in one side that opens and closes. There is also a big triangle, a small triangle, and a small circle. The film opens with the big triangle inside the big square. The small triangle and the small circle then appear. As the big square flaps open and shut, the other geometric figures slide around the screen. After ninety seconds or so, the small triangle and the small circle disappear again.
Re-creation of a screen shot of the Heider and Simmel film (1944), which can be viewed on YouTube. Other researchers have since replicated Heider and Simmel’s findings many times.
When I first watched the film, I didn’t see crude animated shapes moving randomly on a screen; I saw a weirdly powerful geometric allegory. The small triangle was the hero. The big triangle was the villain. And the small circle was the heroine. The small triangle and the small circle enter the screen together, like a couple, and the big triangle storms out of his house (the square). The big triangle violently butts the little guy (small triangle) out of the way and herds the protesting heroine (small circle) back into his house. The big triangle then chases the circle back and forth, trying to work her into a corner. The scene reeks of sexual menace. Eventually the flap in the big square opens, and the small circle flees outside to join the small triangle. The couple (small triangle, small circle) then zip around the screen with the big triangle in hot pursuit. Finally, the happy couple escape, and the big triangle throws a tantrum and smashes his house apart.
It’s a silly interpretation, of course. Like Sherlock Holmes, I’ve composed a rich and confident story from ambiguous clues. But I’m not alone in this. After showing this film to research subjects, Heider and Simmel gave them a simple task: “Describe what you saw.” It’s fascinating to note that o
nly 3 of 114 subjects gave a truly reasonable answer. These people reported seeing geometric shapes moving around a screen, and that was all. But the rest of Heider and Simmel’s subjects were like me; they didn’t see fleshless and bloodless shapes sliding around. They saw soap operas: doors slamming, courtship dances, the foiling of a predator.
Similarly, in the early twentieth century, the Russian filmmaker Lev Kuleshov produced a film of unnarrated images: a corpse in a coffin, a lovely young woman, and a bowl of soup. In between these images, Kuleshov squeezed shots of an actor’s face. The audience noted that when the soup was shown, the actor emoted hunger. When the corpse was shown, he looked sad. When the lovely young woman appeared, the actor’s face was transformed by lust.
Re-creation of the Kuleshov effect. Kuleshov’s original footage is lost, but many re-creations of his experiment can be viewed on YouTube.
In fact, the actor wasn’t emoting at all. After every shot, Kuleshov had inserted exactly the same footage of an actor staring impassively into the camera. There was no hunger, sadness, or lust on the actor’s face except what was put there by the audience. Kuleshov’s exercise shows how unwilling we are to be without a story, and how avidly we will work to impose story structure on a meaningless montage.
IT’S JUST A FLESH WOUND
More than two hundred years ago, James Tilly Matthews invented an elaborate fictional world and lived stubbornly within it. His story is an example of pathological confabulation—of the creation of wild and largely implausible fictions that a person nonetheless believes with “rock-jawed certainty.”
The Storytelling Animal: How Stories Make Us Human Page 9