Young Phineas Gage survived a gruesome accident that punished him cruelly but that led to rare insights into the living brain. From the collection of Jack and Beverly Wilgus.
Raised on a farm in New Hampshire, Phineas Gage demonstrated unusual resourcefulness at a young age. He received little formal education, but sometime in his teens or early twenties he must have concluded that he could better himself by forsaking his family’s hardscrabble existence. Opportunity beckoned: This was the early Industrial Age, an era when railroads were booming, with new companies forming and new lines being built around the country. Gage learned the construction trade and aspired to management. The evidence suggests that he was a good planner who learned from his experiences and incorporated lessons learned in deciding every next step—a recipe for success. By 1848, he had advanced to foreman.
On September 13, 1848, Gage was in charge of a crew that was building a line for the recently chartered Rutland and Burlington Railroad that passed near Cavendish, Vermont. Late that afternoon, he was using a long, tapered metal tool called a tamping iron to pack explosives into a hole cut in rock. Momentarily distracted, he unintentionally let the iron hit the side of the hole. A spark ignited an explosion and the tamping iron shot upward from the hole like a massive bullet, passing through his cheek and head, destroying his left eye and taking out a significant part of the top and bottom front of the left side of his brain. Three feet, seven inches long, and an inch and a quarter in diameter at its thickest point, the tapered iron landed more than sixty feet behind him.
Gage was knocked down and may have briefly lost consciousness, but, amazingly, within a few minutes he was speaking coherently and able to walk. He was taken by oxcart to a nearby hotel, where local doctor Edward H. Williams was called to treat him.
“Doctor, here is business enough for you,” Gage said when Williams arrived.
Not long after, Dr. John M. Harlow took charge of the case. Lying in blood on a bed, Gage pointed to the hole in his left cheek and told Harlow: “The iron entered there and passed through my head.” It was a disturbingly precise description.
Harlow cleaned and dressed Gage’s wounds—and was able, while searching for bone fragments, to touch his right index finger, which he had inserted through the hole in the top of Gage’s head, to the index finger of his left hand, which he had inserted through Gage’s fractured cheek. Harlow later wrote of what he observed: “The brain protruding from the opening and hanging in shreds upon the hair. . . . The pulsations of the brain were distinctly seen and felt.”
Gage’s convalescence was marked by infection and periods of coma; at one point, he was measured for a coffin. In spite of the setbacks, he survived and his speech, memory, and motor control were relatively intact. In late November, Gage returned to his family in New Hampshire. His case had attracted the attention of the press. Under the headline “An Astonishing Fact,” one Boston paper published a letter from one of the many curious people who had seen Gage as he recovered in Cavendish. “We live in an eventful era,” the writer stated, “but if a man can have thirteen pounds of iron in the shape of a pointed bar thrown entirely through his head, carrying with it a quantity of the brain, and yet live and have his senses, we may well exclaim, What next?”
But Gage was not the same man—and therein lay his appeal to the scientific community. Harlow chronicled a profound change in Gage’s personality.
“Has no pain in head, but says it has a queer feeling which he is not able to describe,” the doctor wrote after seeing Gage in April 1849, seven months post-accident.
Applied for his [previous] position as foreman, but is undecided whether to work or travel. His contractors, who regarded him as the most efficient and capable foreman in their employ previous to his injury, considered the change in his mind so marked that they could not give him his place again. The equilibrium or balance, so to speak, between his intellectual faculties and animal propensities, seems to have been destroyed. He is fitful, irreverent, indulging at times in the grossest profanity (which was not previously his custom), manifesting but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires, at times perniciously obstinate, yet capricious and vacillating, devising many plans of future operation which are no sooner arranged than they are abandoned in turn for others appearing more feasible. A child in his intellectual capacity and manifestations, he has the animal passions of a strong man.
What resulted was a sad and nomadic existence. With his brain crippled but still functioning and his left eye permanently closed, Gage was almost literally doomed to wander the earth. He first traveled around New England, exhibiting himself and his tamping iron, apparently for money. He was examined by Harvard surgeon Henry J. Bigelow, who wrote in an 1850 issue of the American Journal of the Medical Sciences that Gage had perhaps survived “the most remarkable history of injury to the brain which has been recorded.” He continued to drift, working for a while as an exhibit in P. T. Barnum’s circus and spending several years as a livery worker in Chile, where a gold rush had attracted foreigners.
Alone save for his mother, he died in San Francisco after a series of seizures in 1860. His brain was not kept for dissection, but his skull and tamping iron wound up in Harvard’s Countway Library of Medicine’s Warren Anatomical Museum. His skull, with its distinctive hole, is today one of the images on the museum’s home page, a macabre symbol of the brain’s enduring power to fascinate and perplex.
Young Phineas Gage survived a gruesome accident that punished him cruelly but that led to rare insights into the living brain. From the collection of Jack and Beverly Wilgus.
Researchers usually interpret the sad tale of Phineas Gage as evidence that different aspects of personality rely on different parts of the brain. This is true enough, but the implications of his transformation are more profound than that: The tamping iron disrupted portions of the top and bottom parts of his brain, impairing how the top-brain system worked with the bottom-brain system. Gage had particular difficulty in integrating his emotional reactions, goals, and motives into his plans—and in knowing when to stick with a plan rather than allowing events to derail him.1
The damage did not simply disrupt certain capacities; it also changed the ways in which Gage’s intact capacities subsequently were used. And his post-accident behavior did not simply reflect the fact that the top and bottom brain were damaged—it also reflected the abnormal ways that his top and bottom brain systems now interacted. By analogy, Richard Gregory in 19612 pointed out that when a resistor is removed from an old-fashioned radio, the radio may squawk. Why does this happen? It’s not because the resistor was a “squawk suppressor,” and removing it eliminated that function. Rather, the squawk occurs because the intact parts of the radio interacted differently after the damage. Similarly, after the accident, Gage’s top-brain and bottom-brain systems changed how they worked together—and the changed interactions produced much of his altered behavior.
The disruptions of the normal interactions between the top- and bottom-brain systems devastatingly changed one major aspect of Gage’s functioning. Wrote Harlow: “Previous to his injury, although untrained in the schools, he possessed a well-balanced mind, and was looked upon by those who knew him as a shrewd, smart businessman, very energetic and persistent in executing all his plans of operation. In this regard, his mind was radically changed, so decidedly that his friends and acquaintances said he was ‘no longer Gage.’ ”
Whereas Gage previously had been strategic and thoughtful, he now was impulsive and unstable. His bottom-brain system interrupted his top-brain system inappropriately, impairing his ability to stick to plans or revise them when he learned the consequences of previous efforts. When his reactions disrupted his plans, he was left awash in a sea of fluctuating emotions and was incapable of responding appropriately. The disruption in how the two brain systems interact had altered how Gage related to other people and how he behaved in the daily situations he encountered.
We have emphasized the importance of thinking of the brain as a system, with inputs, outputs, and specialized processors that produce appropriate outputs for inputs. We’ve also stressed that the top and bottom portions each comprise specialized smaller systems that work together as parts of the greater whole. It is tempting to use the analogy of a computer—and, to a certain extent, the analogy fits. That is to say, brains and computers both process information: In both cases, input (such as from the eyes to the brain, or from a camera to a computer) is stored, transformed, and manipulated, and eventually produces an output (such as a spoken word or an image on a screen).
But brains and computers differ in how they process information. A computer has a separate “central processing unit,” the hardware of the machine that carries out the instructions of programs; separate random-access memory (RAM, which can be increased by adding more memory chips), for quick access to data; and disk or solid-state storage, the machine’s “secondary” or “storage” memory, where data and programs are stored (this kind of memory retains information even when the power is off). Brains, by contrast, don’t have a clear distinction between a central processing unit and memory—and brain structures used to store information over long periods of time (analogous to a computer’s disk or solid-state storage) may also be involved in storing information for brief periods (analogous to a computer’s RAM).
Nonetheless, an insight gleaned from computers is the fact that information processing can be understood only within the context of a system with multiple coordinated components. To illustrate the intricacies of how the top- and bottom-brain systems interact, we can use an analogy of a commercial bakery with two floors.
Let’s say that it’s the week before Thanksgiving. The bakery needs to produce more pumpkin pies because consumer demand is rising, as it does every holiday season. On the top floor are the executives who plan how many pies and other baked goods to produce. Their plans need to take into account various sorts of information, such as the season, day of the week, and availability of specific ingredients (for instance, pumpkins). They then place orders for the ingredients. As the big day approaches, they monitor sales, advance orders, and other indicators, and adjust how many pumpkin pies should be produced. The executives formulate plans based on their expectations, execute them, and then revise their plans as new information arrives.
At the same time, on the bottom floor, many people check that the pumpkins, flour, sugar, and other ingredients arrive, sort them, ensure that the ingredients are fresh (and discard any spoiled ingredients), send them to the appropriate mixers and ovens, and so on. They organize what arrives from the outside world, sort it into categories, and interpret what should be done.
If the floors did not interact, no pumpkin pies (or bread or other baked goods) would be produced. The point is: They do interact. The plans formulated on the top floor are relayed to the workers below, so that they are ready to receive certain ingredients and monitor certain information; and the results of the baking efforts and the information being tracked below (including information about sales) are sent back to the top floor, so that the executives can discover how well their plans are going and adjust them accordingly.
What happens when sales of pumpkin pies are not as good as expected? This information, monitored below by salespeople, is relayed to the executives above. These top-floor employees then scale back how many pies to make the next day, accordingly ordering fewer pumpkins and other ingredients. The workers below would be told to expect less of each ingredient and would be prepared to process the altered amounts. They then let the top floor know the amounts that actually arrived. If the amount of a particular ingredient that they report is more or less than expected, the executives would contact the suppliers of the relevant ingredient (pumpkins, flour, sugar, etc.) and have words with them—ensuring that the bakery didn’t have to pay for more than they requested if too much was shipped or they had sufficient ingredients to fill orders if the shipments were short.
Bringing this back to the brain, consider the following example: You want to go online, so the top-brain system first formulates a plan to turn on your computer and, after it’s on, access your browser. After you turn on the computer, the top-brain system expects to see the sign-in screen; when it appears (and is registered by the bottom-brain system), the top-brain system sets up a plan for entering your password when you start typing. The top-brain system not only generates the commands to control your fingers but also produces expectations about what you should see as each letter appears. It receives input from the bottom brain about which letters appear, and the top-brain system notes if an unexpected letter appears and—if so—revises the plan and corrects the mistake.
This is not to minimize the contributions of the bottom-brain system. When you see a computer screen, the bottom-brain system organizes the pixels into patterns that correspond to words and pictures; it then compares these patterns with all the stored information about things you have seen before; if it finds a match, it applies to the present case the information that you previously associated with the identified object or pattern. Consider your reaction when you see the symbol 
: you know that it means “prohibited” because you’ve seen the symbol before and its meaning has been stored in your memory. When your bottom-brain system matches the input from your eyes to this stored pattern, you then can apply the information you previously associated with it to the present pattern. But more than this, the emotional valance associated with the object that produces the input helps you decide on priorities. If you encounter something that is inherently valued (for example, a hundred-dollar bill on the sidewalk) or aversive (dog droppings on the sidewalk), your ongoing behavior may be interrupted in order for you to pursue a new priority (bending down to pick the money up or moving to the side to avoid stepping on the dog waste).
Moreover, it’s not just that the top system uses the output from the bottom system as part of how it receives feedback about the consequences of acting on a plan; the expectations produced by the top system can bias the bottom system so that it is likely to classify inputs in a specific way. That is, the top brain adjusts the bottom brain so that it can easily perceive what is expected. For example, to a farmer gathering his cows at dusk, even a passing shadow of an appropriate size may be classified by his brain as a cow. Why? The farmer’s expectations, created by the top-brain system, biased the bottom-brain system to classify input as a cow—and biased it so strongly that relatively little input is sufficient to qualify as the expected object.
In addition, the bottom brain draws on the top brain in interpreting the world. The bottom brain automatically classifies objects and interprets scenes and unfolding circumstances by matching them to information previously stored in memory. But sometimes we encounter objects and events that, in combination, don’t match anything familiar; we may be familiar with the individual objects but not the way they are combined.
Say you saw a guy jumping around on one foot, wearing socks over both hands, and singing “America the Beautiful.” Your bottom brain would register each of these things and send the information to the top brain, which then would try to generate a narrative to make sense of the ensemble. Perhaps this is a fraternity initiation rite. The top brain might then generate a plan to confirm or reject this conjecture, perhaps by looking for young men nearby who could be fraternity brothers monitoring the situation. And in so doing, the top brain would prime the bottom brain, making it easier to see the predicted brothers. Without question, the two systems interact.
Depending on the situation, this sort of processing can happen over an extended period of time—or faster than the blink of an eye. Let’s look at the cognitive functions involved when a jet pilot returns to an aircraft carrier: To the aviator, the flight deck appears to be about the size of a postage stamp as the jet approaches. The pilot gently shifts the plane’s controls, slowing it down and initiating descent (all of this in response to top-brain plans). In so doing, he or she expects to see the deck change in specific ways—for example, it should loom larger as the plane approaches it. But if this change (as initially registered in the bottom-brain system) is not as expected (registered in the top-brain system), the pilot will revise the plan. Say a crucial control was set wrong or malfunctioned and the plane did not begin to slow. The bottom-brain system would register that the flight deck is looming larger much more quickly than expected, and would immediately relay this information to the top-brain system. In response, processing in the top-brain system would lead the pilot to check the controls and try to locate the cause of this malfunction. She or he might have to abort the landing, regaining altitude as flight controllers (their own brains engaged in top-bottom interplay) worked to help to resolve the situation.
Such split-second decisions a pilot makes in executing a landing are a testament to the two brain systems’ extraordinary and interacting capabilities. Without the systems’ working together, the pilot never could have gotten the aircraft into the air, never mind returned safely.
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As we saw in chapter 3, numerous connections run between the bottom brain and top brain. For example, a large bundle of nerve fibers called the arcuate fasciculus runs from the temporal lobe to the parts of the frontal lobe involved in producing speech. And numerous connections run to and from areas of the temporal lobe that store memories and various parts of the top-brain system. Clearly, the two brain systems are part of a larger, integrated system. As we shall see in the next chapter, the interactions between the top-brain and bottom-brain systems produce the four modes of thinking that will be our focus in the remainder of this book.