How do children learn to read?
Why is it easy for some people to learn to read and difficult for others?
It's a tough question with a long history. We know that it is not just about natural intelligence, nor is it entirely about constancy and absolute persistence. We also know that there are some conditions that, no matter how hard you try, can slow down a child's learning to read.
Socioeconomic status, for example, has been linked to reading achievement. And, regardless of their background, children with lower verbal ability and those who have difficulty with phonetic processing seem to struggle with this learning. But what lies beneath those differences? How do we learn to translate abstract symbols into meaningful sounds in the first place, and why do some children turn out better than others?
This is the mystery that has driven the work of Fumiko Hoeft (the author of the "write an essay for me" book), a cognitive neuroscientist and psychiatrist now at the University of California, San Francisco. "You know where your eye color, your facial features, your hair, your height comes from. Even her personality: I'm stubborn like my mom, careless like my dad," says Hoeft. "But what we're trying to do is to find out, by looking at the brain networks and the calculations of everything in the child's environment, where his reading ability comes from.
This fall, Hoeft and his colleagues at U.C.S.F. published the results of a three-year, long-term study looking at basic reading developmental neuroscience. Between 2008 and 2009, Hoeft recruited a group of five- and six-year-olds. Some came from environments of apparent reading difficulty. Others seemed to have no obvious risk factors. In addition to undergoing a brain scan, the children were tested on their overall cognitive ability, as well as a number of other factors, including how well they could follow directions and how they could express themselves coherently. Each parent was also tested, and each child's family life was carefully analyzed: How does the child spend his or her time at home? Does he or she read often? How much time does he or she spend watching television? Three years later, each child's brain was scanned again and the children were tested on a series of reading and phonological tests.
She compares it to the story of Dr. Seuss Horton and the egg. Horton sits on an egg that is not his own, and, because of his dedication, the creature that eventually hatches looks half like its natural mother, and half like the elephant. In this particular case, Hoeft and his colleagues still cannot separate cause and effect: Were certain children predisposed to develop strong pathways of white matter that later helped them learn to read, or was it the superior instruction and rich environment that prompted the construction of those pathways?
Hoeft's goal is not just to understand the neuroscience of how children read. Neuroscience is the tool for finding a much deeper question: How should early reading instruction work? In another study, which has just been submitted for publication, Hoeft and his colleagues are trying to turn their understanding of reading ability into helping to identify the most effective teaching methods that could help develop it. Children usually follow a very concrete path to reading. First, there is an approach to the phonological process in which they become aware of the sounds themselves. This awareness is based on phonics, or the ability to decode a sound to match a letter. And finally, it is fused into a complete and automatic reading comprehension. Some children, however, do not follow that path. In some cases, children who have problems with basic phonological awareness, however, master phonetic decoding. There are also children who have problems with decoding, however, their reading comprehension is high. "We want to use these surprising cases to understand what allows people to be resilient," says Hoeft.
She studied, in particular, a concept known as stealth dyslexia: people who have all the ingredients of dyslexia or other reading problems, but end up overcoming them by becoming superior readers. Hoeft may even be one of them: she suspects she suffers from undiagnosed dyslexia. As a child in Japan, she had a difficulty with phonological processing very similar to that experienced by dyslexics, but, at the time, the diagnosis was not common there, it didn't exist for the time being. He unwittingly struggled with his condition and it was not until he entered graduate school that he found a possible explanation for his problem in the scientific literature. The study of stealth dyslexia, proposed by Hoeft, could be the key to finding ways to improve the teaching of reading in general. These stealth dyslexics have reading problems, but are able to develop high comprehension anyway.
Hoeft's group, he told me, has found that stealth dyslexics show a unique dorsolateral prefrontal cortex. That's the part of the brain that is responsible for, among other things, executive function and self-control. In stealth dyslexics, it appears to be particularly well developed. That may be partly because of their genetics, but, Hoeft says, it may also point to a particular educational experience: "If it's the higher executive function that's helping some children develop despite their genetic predisposition to the contrary, that's really good news, because that's something we know very well how to do and that's to train the executive function of the brain. "There are several programs for this and multiple teaching methods, proven in recent years, that help children develop the capacity for self-regulation: for example, KIPP schools are using Walter Mischel's study of self-control to teach children how to delay reward.
What Hoeft's studies show is that no matter what a child's starting point in kindergarten is, reading development also depends heavily on the next three years, and that those three years can be used to teach something that Hoeft now knows is bound to overcome reading difficulty. "That could mean that, in the early stages, we have to pay attention to the executive function," she says. "We have to start not only giving letters, cards and sounds the way we do now, but, especially if we know someone might have difficulty as a reader, look at these other skills, cognitive control and self-regulation. Being a better reader, that is, ultimately, you can associate instruction around things that are not reading.
When Hoeft took into account all the explanatory factors that had been linked in the past to reading difficulties such as genetics, environment, pre-literacy language ability and excess cognitive ability, he found that there is only one factor that determines how good a child's ability to learn to read will be. The growth of white matter in a specific area of the brain, the left temporoparietal region. The amount of white matter a child arrives at in kindergarten does not make a difference. But the change in volume of this matter between kindergarten and third grade does.
What is white matter? You can think of it as a kind of neural highway in the brain, pathways that connect different parts of the cortex and the surface of the brain. Information in the form of electrical signals circulate through the white matter, allowing communication between different parts of the brain: you see something, you give it a meaning, and you interpret that meaning. Hoeft recorded an increase in the volume of pathways in the left temporoparietal area, which is central to phonological processing, speech and reading. Or, as Hoeft puts it, "which is where the tedious work of linking sounds and letters and corresponding order is done." Their results suggest that if the increase in white matter does not occur at the critical moment, children will have a hard time finding a way to look at the cards and then convert them into words that have some meaning.
Hoeft's discovery is based on previous research she conducted on dyslexia. In 2011 she found that while there is a measure of behavior that could predict which dyslexic children would improve their reading skills, increased neural activation in the right prefrontal cortex of the brain along with the distribution of white matter could, with 72% accuracy, offer such a prediction. She observed an overview of brain activation as children perform an initial phonological task, the predictive power rising to over 90%. Intelligence and I.Q. did not matter; what was key was a very specific organizational model within her brain.
The group's new findings go a step further. They not only show that white matter is important. They point to a crucial stage in the development of white matter that is fundamental to reading ability. And the development of white matter, Hoeft believes, is certainly a function of both nature and nurture. "Our findings could be interpreted to mean that there is still genetic influence," says Hoeft, noting that pre-existing structural differences in the brain can indeed influence future white matter development. But, he adds, "it is also likely that the development of dorsal white matter is representing the environment that children are exposed to between kindergarten and third grade. The environment at home, the school environment, the type of reading instruction they are receiving. ”