Within the brain, neurons compete. Unused neurons are eliminated; the winners survive, and if used often, eventually get insulated with a layer of white fatty tissue, which exponentially increases the speed of transmission. In this way, gray matter gets upgraded to white matter. This doesn’t happen throughout the brain all at once; rather, some parts of the brain can still be adding gray matter while other regions are already converting it to white matter. However, when it occurs, this upgrade can be rapid—in some areas, 50% of nerve tissue gets converted in a single year.
The result can be leaps in intellectual progress, much like a dramatic growth spurt in height. During middle childhood, faster upgrading of left hemisphere regions leads to larger gains in verbal knowledge. The area of the prefrontal cortex considered necessary for high-level reasoning doesn’t even begin upgrading until preadolescence—it’s one of the last to mature.
In those same years, the brain is also increasing the organization of the large nerve capsules that connect one lobe to another. Within those cerebral superhighways, nerves that run parallel are selected over ones that connect at an angle. Slight alterations here have whopping effects—a 10% improvement in organization is the difference between an IQ below 80 and an IQ above 130. Such 10% gains in organization aren’t rare; on the contrary, that’s normal development from age 5 to 18.
With all this construction going on, it’s not surprising that IQ scores show some variability in the early years. From age 3 to age 10, two-thirds of children’s IQ scores will improve, or drop, more than 15 points. This is especially true among bright kids—their intelligence is more variable than among slower children.
Dr. Richard Haier is an eminent neurologist at University of California, Irvine. When I told him that New York City was selecting gifted students on the basis of a one-hour exam at age five, he was shocked.
“I thought school districts ended that practice decades ago,” Haier said. “When five-year-olds are tested, it’s not clear to me that having a single snapshot in the developmental sequence is going to be that good, because not every individual progresses through development at the same rate. What about the kid who doesn’t progress until after age five?”
Haier’s specialty is identifying the location of intelligence in the brain. Neuroscience has always been obsessed with isolating the functions of different brain regions. Early findings came from patients with damage to discrete regions; from what they could not do, we learned where visual processing occurs, and where motor skills are stored, and where language is comprehended.
In the last decade, brain-scanning technology enabled us to decipher far more—we know what lights up when danger is imminent, and where religious sense is experienced, and where in the brain lie the powerful cravings of romantic love.
But the search for intelligence in the brain lagged. At last, neuroscientists like Haier are on the verge of identifying the precise clusters of gray matter that are used for intelligence in most adults. But during their hunt, they collectively discovered something that has made them rethink the long-held assumption that ties brain location to brain function.
As a child ages, the location of intellectual processing shifts. The neural network a young child relies on is not the same network he will rely on as an adolescent or adult. There is significant overlap, but the differences are striking. A child’s ultimate intellectual success will be greatly affected by the degree to which his brain learns to shift processing to these more efficient networks.
Dr. Bradley Schlaggar, a neurologist at Washington University in St. Louis, has found that both adults and children called upon 40 distinct clusters of their gray matter when subjects performed a simple verbal test inside an fMRI scanner. However, comparing the scans of the children (age 9) to adults (age 25), Schlaggar saw that only half of those clusters were the same. The adults were utilizing their brains quite differently.
Similarly, Dr. Kun Ho Lee of Seoul National University gave IQ puzzles to two groups of Korean high schoolers inside a scanner. The brains of the smart teens had shifted processing to a network recruiting the parietal lobe; they tested in the top one percent. The brains of the normal teens had not made this shift.
Other scholars are finding this as well. Teams at Cornell, Stanford, and King’s College, London, have all found that children’s cognitive networks aren’t the same as adults’.
“This is so contradictory to the old principles of neuroscience,” remarked a gleeful Haier. “The research is going in a new direction, that intelligence moves throughout the brain as different brain areas come online.”
From the unfinished cortex to the shift in neural networks, none of the critical mechanisms of intelligence are yet operational at the age most children are taking a test for entry into a gifted program or a private K through 8 school. We are making long-term structural decisions over kids’ lives at a point when their brains haven’t even begun the radical transformations that will determine their true intelligence.
Real intellectual development doesn’t fit into nicely rounded bell curves. It’s filled with sharp spikes in growth and rough setbacks that have to be overcome.
We need to question why this idea of picking the smart children early even appeals to us. We set this system up to make sure natural talent is discovered and nurtured. Instead, the system is failing a majority of the kids, and a lot of natural talent is being screened out.
It may sound trite to ask, “What about the late bloomers?” But in terms of truly superior cognitive development, the neuroscience suggests that “later” may be the optimal rate of development. And it’s not as if society needs to wait forever for these later developers to bloom; the system of screening children would be significantly more effective if we simply waited until the end of second grade to test them.
It’s common for gifted children to make uneven progress. (It’s not unheard of for a gifted child’s scores across verbal and nonverbal skills to be so disparate that one half of a test result could qualify for an advanced program while the other half could send the kid to special ed.)
The way most programs are currently designed, admissions officers never consider that uneven development may actually be an asset. The young child who masters cognitive skills but struggles in phonics might later approach the abstract language of poetry in a profoundly new way. A four-year-old’s single-minded fascination with dinosaurs to the exclusion of anything else might not mark a deficit; instead, it might allow him to develop focus and an approach to learning that will serve him well in any other context.
Think of the little girl kept out of a gifted program—despite the fact that she’d been reading since she was two—because she wasn’t manually coordinated enough to put four blocks in a perfect row.
In the meantime, the late-blooming child lives with the mistaken fact that she is not gifted—but she’s bright enough to understand that the Powers That Be have decreed that it would be a waste of time and resources to develop her potential. The gifted rolls have already been filled.