The uses of reason



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MIschel’s results were very surprising, at least to him. There was a strong correlation between the behavior of the four-year-old waiting for a marshmallow and that child’s future behavior as a young adult. The children who rang the bell within a minute were much more likely to have behavioral problems later on. They got worse grades and were more likely to do drugs. They struggled in stressful situations and had short tempers. Their SAT scores were, on average, 210 points lower than those of kids who’d waited several minutes before ringing the bell. In fact, the marshmallow test turned out to be a better predictor of SAT results than the IQ tests given to the four-year-olds.

The ability to wait for a second marshmallow reveals a crucial talent of the rational brain. When MIschel looked at why some four-year-olds were able to resist ringing the bell, he found that it wasn’t because they wanted the marshmallow any less. These kids also loved sweets. Instead, Mischel discovered, the patient children were better at using reason to control their impulses. They were the kids who covered their eyes, or looked in the other direction, or managed to shift attention to something other than the delicious marshmallow sitting right there.

Rather than fixating on the sweet treat, they got up from the table and looked for something to play with. It turned out that the same cognitive skills that allowed these kids to thwart temptation also allowed them to spend more time on their homework. In both situations, they prefrontal cortex was forced to exercise its cortical authority and inhibit the impulses that got in the way of their goal.

Studies of children with attention deficit hyperactivity disorder (ADHD) further demonstrate the connection between the prefrontal cortex and the ability to withstand emotional urges. Approximately 5 percent of school-age children are affected by ADHD, which manifests itself as an inability to focus, sit still, or delay immediate gratification. (These are the kids who eat their marshmallows right away.) As a result, kids with ADHD tend to perform significantly worse in school, since they struggle to stay on task. Minor disturbances become overwhelming distractions.

In November 2007, a team of researchers from the National Institute of Mental Health and McGill University announced that they had uncovered the specific deficits of the ADHD brain. The disorder turns out to be largely a developmental problem; often, the brains of kids with ADHD develop at a significantly slower pace than normal. This lag was most obvious in the prefrontal cortex, which meant that these kids literally lacked the mental muscles needed to resist alluring stimuli. (On average, their frontal lobes were three and a half years behind schedule.) The good news, however, is that the brain almost always recovers from its slow start. By the end of adolescence, the frontal lobes in these kids reached normal size. It’s not a coincidence that their behavioral problems began to disappear at about the same time. The children who had had the developmental lag were finally able to counter their urges and compulsions. They could look at the tempting marshmallows and decide that it was better to wait.

ADHD is an example of a problem in the developmental process, but the process itself is the same for everybody. The maturation of the human mind recapitulates its evolution, so the first parts of the brain to evolve—the motor cortex and brain stem—are also the first parts to mature in children. Those areas are fully functional by the time humans hit puberty. In contrast, brain areas that are relatively recent biological inventions—such as the frontal lobes—don’t finish growing until the teenage years are over. The prefrontal cortex is the last brain area to fully mature.

This developmental process holds the key to understanding the behavior of adolescents, who are much more likely than adults to engage in risky, impulsive behavior. More than 50 percent of U.S. high school students have experimented with illicit drugs. Half of all reported cases of sexually transmitted diseases occur in teenagers. Car accidents are the leading cause of death for those under the age of twenty-one. These bleak statistics are symptoms of minds that can’t restrain themselves. While the emotional brains of teens are operating at full throttle (those raging hormones don’t help), the mental muscles that check these emotions are still being built. A recent study by neuroscientists at Cornell, for example, demonstrated that the nucleus accumbens, a brain area associated with the processing of rewards—things like sex, drugs, and rock ‘n’ roll—was significantly more active and mature in the adolescent brain than the prefrontal cortex was, that part of the brain that helps resist such temptations. Teens make bad decisions because they are literally less rational.5

This new research on reckless adolescents and children with ADHD highlights the unique role of the prefrontal cortex. For too long, we’ve assumed that the purpose of reason is to eliminate those emotions that lead us astray. We’ve aspired to the Platonic model of rationality, in which the driver is in complete control. But now we know that silencing human feelings isn’t possible, at least not directly. Every teenager wants to have sex, and every four-year-old wants to eat marshmallows. Every firefighter who sees a wall of flames wants to run. Human emotions are built into the brain at a very basic level. They tend to ignore instructions.

But this doesn’t mean that humans are mere puppets of the limbic system. Some people can see through the framing effect despite the fact that their amygdalas are activated. Some four-year-olds can find ways to wait for the second marshmallow. Thanks to the prefrontal cortex, we can transcend our impulses and figure out which feelings are useful and which ones should be ignored.

Consider the Stroop task, one of the classic experiments of twentieth-century psychology. Three words—blue, green, and red—are flashed randomly on a computer screen. Each of the words is printed in a different color, but the colors aren’t consistent. The word red might be in green, while blue is in red. The surprisingly difficult job of the subject is to ignore the meaning of the word and focus instead on the color of the word. If you’re looking at green, but the word is actually in blue letters, then you have to touch the button marked blue.

Why is this simple exercise so hard? Reading the word is an automated task; it takes little mental effort. Naming the color of the word, however, requires deliberate thought. The brain needs to turn off its automatic operation—the act of reading a familiar word—and consciously think about what color it sees. When a person performs the Stroop task in an fMRI machine, scientists can watch the brain struggle to ignore the obvious answer. The most important cortical area engaged in this tug of war is the prefrontal cortex, which allows a person to reject the first impression when it’s possible that the first impression might be wrong. If the emotional brain is pointing you in the direction of a bad decision, you can choose to rely on your rational brain instead. You can use your prefrontal cortex to discount the amygdala, which is telling you to run up the steep slopes of the gulch. The reason Wag Dodge survived was not that he wasn’t scared. Like all the smokejumpers, he was terrified. Dodge survived because he realized that his fright wasn’t going to save him.



THE EXECUTIVE IN THE COCKPIT

The ability to supervise itself, to exercise authority over its own decision-making process, is one of the most mysterious talents of the human brain. Such a mental maneuver is known as executive control, since thoughts are directed from the top down, like a CEO issuing orders. As the Stroop task demonstrates, this thought process depends on the prefrontal cortex.

But the questions still remain: How does the prefrontal cortex wield such power? What allows this particular area to control the rest of the brain? The answer returns us to the cellular details: by looking at the precise architecture of the prefrontal cortex, we can see the neural forms that explain its function.

Earl Miller is a neuroscientist at MIT who has devoted his career to understanding this bit of brain tissue. He was first drawn to the prefrontal cortex as a graduate student, in large part because it seemed to be connected to everything. “No other brain area gets so many different inputs or has so many different outputs,” Miller says. “You name the brain area, and the prefrontal cortex is almost certainly linked to it.” It took more than a decade of painstaking probing while Miller carefully monitored cells all across the monkey brain, but he was eventually able to show that the prefrontal cortex wasn’t simply an aggregator of information. Instead, it was like the conductor of an orchestra, waving its baton and directing the musicians. In 2007, in a paper published in Science, Miller was able to provide the first glimpse of executive control at the level of individual neurons, as cells in the prefrontal cortex directly modulated the activity of cells throughout the brain. He was watching the conductor at work.

However, the prefrontal cortex isn’t merely the bandleader of the brain, issuing one command after another. It’s also uniquely versatile. While every other cortical region is precisely tuned for specific kinds of stimuli—the visual cortex, for example, can deal only with visual information—the cells of the prefrontal cortex are extremely flexible. They can process whatever kind of data they’re told to process. If someone is thinking about an unfamiliar math problem on a standardized test, then her prefrontal neurons are thinking about that problem. And when her attention shifts, and she starts to contemplate the next question on the test, these task-dependent cells seamlessly adjust their focus. The end result is that the prefrontal cortex lets her consciously analyze any type of problem from every possible angle. Instead of responding to the most obvious facts, or the facts that her emotions think are most important, she can concentrate on the facts that might help her come up with the right answer. We can all use executive control to get creative, to think about the same old problem in a new way. For instance, once Wag Dodge realized that he couldn’t outrun the flames and that the fire would beat the smokejumpers to the top of the ridge, he needed to use his prefrontal cortex to come up with a new solution. The obvious response wasn’t going to work. As Miller notes, “That Dodge guy had some high prefrontal function.”

Consider the classic psychology puzzle known as the “candle problem.” A subject is given a book of matches, some candles, and a cardboard box containing a few thumbtacks. The person is told to attach the candle to a piece of corkboard in such a way that it can burn properly. Most people initially attempt two common strategies, neither of which will work. The first strategy is to tack the candle directly to the board; this causes the candle wax to shatter. The next is to use the matches to melt the bottom of the candle and then try to stick the candle to the board; the wax does not hold, and the candle falls to the floor. At this point, most people give up. They tell the scientists that the puzzle is impossible; it’s a stupid experiment and a waste of time. Less than 20 percent of people manage to come up with the correct solution, which is to attach the candle to the cardboard box and then tack the cardboard box to the board. Unless the subject has an insight about the box—that it can do more than hold thumbtacks—candle after candle will be wasted. The subject repeats his failures while waiting for a breakthrough.

People with frontal-lobe lesions can never solve puzzles like the candle problem. Although they understand the rules of the game, they are completely unable to think creatively about the puzzle, to look past their initial (and incorrect) answers. The end result is that the frontal-lobe patient fails to execute the counterintuitive moves required to solve the puzzle, even though the obvious moves have failed. Instead of trying something new, or relying on abstract thought, the subject keeps attempting to tack the candle to the board, stubbornly insisting on this strategy until there are no more candles.



Mark Jung-Beeman, a cognitive psychologist at Northwestern University, has spent the last fifteen years trying to understand how the brain, led by the frontal cortex, manages to come up with such creative solutions. He wants to find the neural source of our breakthroughs. Jung-Beeman’s experiments go like this: he gives a subject three words (such as pine, crab, and sauce) and asks him to think of a single word that could form a compound word or phrase with all three. (In this case, the answer is apple: pineapple, crab apple, applesauce.) What’s interesting about this type of verbal puzzle is that the answers often arrive in a flash of insight, the familiar “aha!” moment. People have no idea how they came up with the necessary word, just as Wag Dodge couldn’t explain how he invented the escape fire. Nevertheless, Jung-Beeman found that the mind was carefully preparing itself for the epiphany; every successful insight was preceded by the same sequence of cortical events. (He likes to quote Louis Pasteur: “Chance favors the prepared mind.”)

The first brain areas activated during the problem-solving process were those involved in executive control, such as the prefrontal cortex and anterior cingulate cortex. The brain was banishing irrelevant thoughts so that the task-dependent cells could properly focus. “You’re getting rid of those errant daydreams and trying to forget about the last word puzzle you worked on,” Jung-Beeman says. “Insight requires a clean slate.”http://images1.wikia.nocookie.net/__cb20060329230755/psychology/images/1/1d/superior_temporal_gyrus.png

After exercising top-down control, the brain began generating associations. It selectively activated the necessary brain areas, looking for insights in all the relevant places, searching for the association that would give the answer. Because Jung-Beeman was giving people word puzzles, he saw additional activation in areas related to speech and language, such as the superior temporal gyrus in the right hemisphere. (The right hemisphere is particularly good at generating the kind of creative associations that lead to epiphanies.) “Most of the possibilities your brain comes up with aren’t going to be useful,” he says. “And it’s up to the executive-control areas to keep on looking or, if necessary, change strategies and start looking somewhere else.”

But then, when the right answer suddenly appeared—when apple was passed along to the frontal lobes—there was an immediate realization that the puzzle had been solved. “One of the interesting things about such moments of insight,” says Jung-Beeman, “is that as soon as people have the insight, they say it just seems obviously correct. They know instantly that they’ve solved the problem.”

This act of recognition is performed by the prefrontal cortex, which lights up when a person is shown the right answer, even if he hasn’t come up with the answer himself. Of course, once the insight has been identified, those task-dependent cells in the frontal lobes immediately move on to the next task. The mental slate is once again wiped clean. The brain begins preparing itself for another breakthrough.

On the afternoon of July 19, 1989, United Airlines Flight 232 took off from Denver Stapleton Airport, bound for Chicago. The conditions for the flight were ideal. The morning thunderstorms had passed, and the sky was a cloudless cerulean blue. Once the DC-10 reached its cruising altitude of 37,000 feet, about thirty minutes after takeoff, Captain Al Haynes turned off the seat-belt sign. He didn’t expect to turn it back on until the plane began its descent.

The first leg of the flight went smoothly. A hot lunch was served to the passengers. The plane was put on autopilot, with supervision by the first officer, William Records. Captain Haynes drank a cup of coffee and stared at the cornfields of Iowa far below. He’d flown this exact route dozens of times before—Haynes wan one of United’s most experienced pilots, with more than thirty thousand hours of flight time—but he never ceased to admire the grid of flat land, the farms laid out in such perfectly straight lines.

At 3:16 in the afternoon, about an hour after takeoff, the quiet of the cockpit was shattered by the sound of a loud explosion coming from the back of the plane. The frame of the aircraft shuddered and lurched to the right. Haynes’s first thought was that the plane was breaking up, that he was about to die in a massive fireball. But then, after a few seconds of gnashing metal, the quiet returned. The plane kept on flying.

Haynes and First Officer Records immediately began scanning the cluster of instruments and dials, looking for some indication of what had gone wrong. The pilots noticed that the number two engine, the middle engine in the rear of the plane, was no longer operating. (Such a failure can be dangerous, but it’s rarely catastrophic, since the DC-10 also has two other engines, one on each wing.) Haynes got out his pilot manual and started going through the engine-failure checklist. The first order of business was to shut off the fuel supply to that engine, in order to minimize the risk of an engine fire. They attempted it, but the fuel lever wouldn’t move.

It had now been a few minutes since the explosion. Records was flying the plane. Haynes was still trying to fix the fuel lines; he assumed that the plane was maintaining its scheduled flight path to Chicago, albeit at a slightly slower pace. That’s when Records turned to him and said the one thing a pilot never wants to hear: “Al, I can’t control the airplane.” Haynes looked over at Records, who had applied full left aileron and pushed the yoke so far forward that the controls were pressed against the cockpit dash. Under normal circumstances, such a maneuver would have caused the plane to descend and turn left. Instead, the plane was in a steep ascent with a sharp right bank. If the plane banked much more, it would flip over.

What could trigger such a complete loss of control? Haynes assumed there had been a massive electronic failure, but the circuit board looked normal. So did the onboard computers. Then Haynes checked the pressure on his three hydraulic lines: they were all plummeting toward zero. “I saw that and my heart skipped a beat,” Haynes remembers. “It was an awful moment, the first time I realized that this was a real disaster.” The hydraulic systems control the plane. They are used to adjust everything from the rudder to the wing flaps. Planes are always engineered with multiple, fully independent hydraulic systems; if one fails, the backup system can take its place. This redundancy means that a catastrophic failure of all three lines simultaneously should be virtually impossible. Engineers calculate the odds of such an event at about a billion to one. “It wasn’t something we ever trained for or practiced,” Haynes says. “I looked in my pilot manual, but there was nothing about a total loss of hydraulics. It just wasn’t supposed to happen.”

But that’s exactly what had happened to this DC-10. For some reason, the loss of the engine had ruptured all three hydraulic lines (Investigators later discovered that the engine fan disc had fractured, sending shards of metal through the tail section where all the hydraulic lines were located.) Haynes could remember only one other instance when an aircraft had lost all of its hydraulic controls. Japan Airlines Flight 123, a Boeing 747 flying from Tokyo to Osaka in August 1985, had suffered a similar catastrophe after its vertical stabilizer was blown off by an explosive decompression event. The aircraft had steadily drifted downward for more than thirty minutes, eventually crashing into the face of a mountain. More than five hundred people died. It was the deadliest single-aircraft disaster in history.

Back in the cabin, the passengers were beginning to panic. Everyone had heard the explosion; they all could feel the plane careening out of control. Dennis Fitch, a United Airlines flight instructor, was sitting in the middle of the aircraft. After the terrifying boom—“It sounded like the plane was breaking apart,” Fitch said—he visually inspected the wings of the plane. There were no obvious signs of damage, although he couldn’t figure out why the pilots weren’t correcting the plane’s steep bank. Fitch knocked on the cockpit doors to see if he could offer any assistance. He taught pilots how to fly the DC-10, so he knew the aircraft inside and out.

“It was an amazing scene,” Fitch remembers. “Both pilots were at the controls, their tendons in their forearms were raised from effort, their knuckles were white from gripping the handles, but it wasn’t doing anything.” When the pilots told Fitch that they had lost hydraulic pressure in all three hydraulic systems, Fitch was shocked. “There was no procedure for this. When I heard that, I thought, I’m going to die this afternoon.”

Captain Haynes, meanwhile, was desperately trying to think of some way to regain control. He placed a radio call to United Airlines System Aircraft Management (SAM), a crew of aircraft engineers specially trained to help deal with in-flight emergencies. “I thought, these guys must know a way out of this mess,” Haynes says. “That’s their job, right?”

But the engineers at SAM weren’t any help. For starters, they didn’t believe that all of the hydraulic pressure was really gone. “SAM kept on asking us to check the hydraulics again,” Haynes says. “They told us that thee must be some pressure left. But I kept on telling them that there was none. All three lines were empty. And then they kept on telling us to check the pilot’s manual, but the manual didn't deal with this problem. Eventually, I realized that we were on our own. Nobody was going to land the plane for us.”

Haynes began by making a mental list of the cockpit elements that he could operate without hydraulic pressure. The list was short. In fact, Haynes could only think of one element that might still be useful: the thrust levers, which controlled the speed and power of his two remaining engines. (They are like the gas pedals of the plane.) But what does thrust matter if you can’t maneuver? It would be like revving a car without a steering wheel.

Then Haynes had an idea. At first, he dismissed it as crazy. The more he thought about it, however, the less ridiculous it seemed. His idea was to use his thrust levers to steer the plane. The key was differential thrust; thrust is the forward-directed force of an airplane engine, and a difference in thrust between the plane’s engines is normally something pilots want to avoid. But Haynes figured that if he idled one engine while the other got a boost of power, the plane should turn to the idled side. The idea was grounded in simple physics, but he had no idea if it would actually work.

There was little time to lose. The bank of the plane was approaching 38 degrees. If it got past 45 degrees, the plane would flip over and enter a death spiral. So Haynes advanced the throttle for the right engine and idled the left. At first, nothing happened. The plane stayed in a steep bank. But then, ever so slowly, the right wing began to level itself. The plane was now flying in a straight line. Haynes’s desperate idea had worked.

Flight 232 was given instructions to land a Sioux City, Iowa, a regional airport about ninety miles to the west. Using nothing but variations in engine thrust, the pilots began a steady right-hand turn. It had been about twenty minutes since the initial explosion, and it seemed as if Haynes and his crew had restored a measure of control to the uncontrollable plane. “I felt like we were finally making some progress,” Hayes says. “It was the first time since the explosion that I thought we just might be able to get this bird on the ground.”hugoid

But just as the flight crew was starting to gain a little confidence, the plane started to pitch violently up and down in a relentless cycle. This is know as a phugoid pattern. Under normal flight conditions, phugoids are easy to manage, but since the plane was without any hydraulic pressure, Haynes and his crew were unable to modulate the pitch of the aircraft. The pilots realized that unless they found a way to dampen the phugoids, they could end up like the Japan Airlines’ Flight 123. They would careen in a sine wave as they steadily lost altitude. And then they’d crash into the cornfields.

How do you control phugoids in such a situation? At first glance, the answer seems obvious. When the nose of the plane is pitched down, and the air speed is increasing, a pilot should decrease the throttle, so that the plane slows down. And when the plane is pitched up, and the air speed is decreasing, a pilot should increase the throttle in order to prevent a stall. “You’re looking at your airspeed indicator, and the natural reaction of a pilot is to try to balance out what’s happening,” Haynes says. But that instinctive reaction is exactly the opposite of what should be done. The aerodynamics of flight contradict common sense; if Haynes had gone with his first impulse, he would soon have lost control of the plane. The aircraft would have entered a steep, unstoppable descent.

Instead of doing that, Haynes carefully thought through the problem. “I tried to imagine what would happen to the plane depending on how I controlled the thrust levers,” he says. “It took me a few minutes, but that saved me from making a big mistake.” Haynes realized that when the nose tilted down and the air speed built up, he needed to increase power, so that the two remaining engines could bring up the nose. Because the engines on a DC-10 are set below the wings, an increase in engine throttle will cause the plane to pitch up. In other words, he needed to accelerate on the downhill and brake on the uphill. It was such a counterintuitive ideas that Haynes could barely bring himself to execute the plan. “The hardest part,” Haynes said, “was when the nose started up and the air speed started to fall, and then you had to close the throttles. That wasn’t very easy to do. You felt like you were going to fall out of the sky.

But it worked. The pilots managed to keep the plane reasonably level. They couldn’t get rid of the phugoid motion—that would have required actual flight controls—but they kept it from turning into a deadly dive. The flight crew was now able to focus on their final problem: orchestrating a descent into Sioux City. Haynes knew it would be a struggle. For one thing, the pilots couldn’t directly control their rate of descent, since the elevators of the aircraft—the control surfaces in the tail wing of the plane that modulate altitude—were completely unresponsive. Haynes and the pilots were forced to rely on a rough formula used when flying the DC-10: a thousand foot drop in altitude takes approximately three miles in distance. Since the aircraft was now about sixty miles from the airport but was maintaining an altitude of approximately thirty thousand feet, Haynes realized they’d need to make a few loops on their way to the runway. If they tried to rush the descent, they’d risk losing what little stability they had. And so the pilots began a series of right-hand turns as they proceeded northwest to Sioux City. With each turn, they lost a little more altitude.

As the plane neared the airport, the pilots made final preparations for an emergency landing. Excess fuel was dumped and the throttles were gradually eased. The passengers were told to assume the brace position, with their heads tight against their knees. Haynes could see the landing strip and the fire engines in the distance. Although the pilots had been flying without controls for forty minutes, they still managed to line up the plane in the middle of the runway, with its wheels down and its nose up. It was an incredible feat of airmanship.

Unfortunately, the pilots had no control over the speed of the plane. They also couldn’t brake once they hit the runway. “You normally land the DC-10 at approximately a hundred and forty knots,” Haynes says. “We were doing two hundred and fifteen knots and accelerating. You normally touch down at about two to three hundred feet per minute at the most, as a rate of descent. We were doing eighteen hundred and fifty feet per minute. And increasing. And you normally like to go straight down the runway, and we were drifting left and right because of the tail wind.”

These factors meant that the plane couldn’t stay on the tarmac. It skidded through a cornfield and shattered into several sections. The cockpit broke apart from the main body of the plane, like the tip of a pencil, and tumbled end over end to the edge of the airfield.(All of the pilots were knocked unconscious and suffered life-threatening injuries.) A fire broke out in the fuselage. Toxic black smoke filled the main cabin. When the smoke cleared, 112 passengers were dead. http://www.airdisaster.com/special/united2.jpg

But the piloting skills of the flight crew—their ability to control a plane without any controls—meant that 184 passengers survived the accident. Because the plane made it to the airport, emergency responders wee able to treat the wounded and quickly extinguish the flames. As the National Transportation Safety Board concluded in their authoritative report, “The performance [of the pilots] was highly commendable and greatly exceeded reasonable expectations.” The method of flight control invented in the cockpit of Flight 232 is now a standard part of pilot training.



WORKING MEMORY

The first remarkable thing about the performance of the pilots is that they managed to keep their emotions in check. It’s not easy to maintain poise when you’ve lost complete control of your aircraft. In fact, Haynes later admitted that he didn’t expect to survive the flight. He assumed that Flight 232 would eventually spiral out of control, that the phugoids would get worse and worse until the plane finally crashed into the ground. “I thought the best-case scenario was that we’d make the runway but crash-land,” Haynes says. “And I was still pretty sure that I wouldn’t survive that.”



And yet, Haynes never let his fear turn into panic. He was in a situation of incomprehensible pressure, confronted with a scenario that was never supposed to happen, but he managed to keep his cool. Such restraint was possible only because Haynes, like Wag Dodge, used his prefrontal cortex to manage his emotions. After the three hydraulic lines failed, the pilot realized that his trained instincts didn’t know how to land the plane. Emotions are adept at finding patterns based on experience, so that a person can detect the missile amid the blur of radar blips. But when you encounter a problem you’ve never experienced before, when you dopamine neurons have no idea what to do, it’s essential that you try to tune out your feelings. Pilots call such a state “deliberate calm,” because staying calm in high-pressure situations requires conscious effort. “Maintaining our composure was one of the hardest things we had to do,” Haynes says. “We knew we had to focus and think straight, but that’s not always so easy.”

1 Chapter 4 of How We Decide by Jonah Lehrer, 2009, Houghton Mifflin Harcourt.

2 Read a memorial statement about Wag Dodge from a fellow alumnus of the University of Utah: http://www.alumni.utah.edu/u-news/july04/memorial.htm


3 Although certain section of this brain area, such as the orbitofrontal cortex, are actually concerned with the perception of emotional states, the upper two-thirds of the prefrontal cortex—particularly the dorsolateral prefrontal cortex, or DLPFC—is generally regarded as the rational center of the brain. When you crunch numbers, deploy logic, or rely on deliberate analysis, you’re using your DLPFC.

4 And then there’s the case of the married, middle-aged Virginia schoolteacher who suddenly started downloading child pornography and seducing young girls. His behavior was so brazen that he was quickly arrested and convicted of child molestation; he was sent to a treatment program for pedophiles, but he was expelled from the program after propositioning several women there. Having failed rehab, he was to appear in court for sentencing, but the day before his court date, he went to the emergency room complaining of blinding headaches and a constant urge to rape his neighbor. After ordering an MRI, the doctors saw the source of the problem; he had a massive tumor lodged in his frontal cortex. After the tumor was removed, the deviant sexual urges immediately disappeared. The man was no longer a hypersexual monster. Unfortunately, this reprieve was brief; the tumor started to grow back within a year. His frontal cortex was once again incapacitated, and the urges of pedophilia returned.

5 But there are ways to compensate for the irrational brains of teens. For instance, when West Virginia revoked driving permits for students who were under the age of eighteen and who dropped out of school, the dropout rate fell by one-third in the first year. While teens were blind to the long-term benefits of getting a high school diploma, they could appreciate the short-term punishment of losing a license. The New York City schools have recently begun experimenting with a program that pays students for improving their standardized test scores; initial results have been extremely encouraging. By focusing on immediate rewards, these incentive programs help correct for the immature prefrontal cortices of children and teenagers.




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