The Dyslexic Advantage Read online

  The phonological processing system also plays an important role in many attention-related functions, including working memory and executive functioning. Working memory is the kind of short- to intermediate-term memory that helps us “keeps things in mind” for active conscious processing—very much like the random-access memory or RAM on your computer. The phonological processing system forms a phonological loop (or short-term memory tracing) that keeps auditory-verbal information alive in active working memory until it can be processed, organized, and put to use.

  When auditory-verbal working memory is limited (or has too short a functional span), the brain may fail to finish all the processing it needs to perform before this “internal speech tracing” fades away. The result is working memory overload, which causes symptoms like inaccurate language processing, slower language-based learning, problems with organization and task management, and the appearance of inattention during difficult work. Working memory overload resembles what happens when you try to run a memory-intensive software program on a computer with too little keyboard memory. At first the program runs more slowly; then it begins to flash error messages; and finally it jams up completely.

  Problems with working memory overload are very common in dyslexic students. They often first appear during the early elementary years, when complex tasks like reading, writing, and math are first introduced; peak again during the middle elementary years, when organization and study skills are first stressed; then cause another peak of challenges during middle and high school when language and organizational demands become even more complex.

  Importantly, working memory also plays a key role in other aspects of attention or “executive function” like organization, planning, implementation, and oversight of tasks. That’s why when working memory is limited due to problems with phonological processing, students can experience a whole range of challenges with attention. Often such students are diagnosed with inattentive ADHD.

  Problems with phonological processing are usually attributed to structural variations in the brain’s left hemisphere, particularly in the language areas of the left temporal lobe. The precise nature of these variations isn’t fully known. Some researchers believe they are caused by alterations in processes that take place very early in development, when brain cells organize themselves into functional networks. Because the networks don’t form in a well-integrated fashion, the processing of phonological information is impaired. 3 Other researchers have proposed that these impairments are caused by difficulties in learning rule-based procedures or by inherited variations in the structure of the brain’s circuitry. We’ll discuss these hypotheses in more detail in the rest of this chapter and the next.

  For the moment, however, let’s focus on the key question of whether phonological processing impairments by themselves seem capable of causing all the challenges and strengths associated with dyslexia. It shouldn’t take us long to see that they cannot. For example, there’s no direct relationship between poor phonological processing and common dyslexia-associated difficulties like problems with finger coordination for handwriting, eye movement control for reading, or speech muscle control for speech articulation. Even more importantly, phonological processing impairments provide no explanation for the kinds of dyslexic advantages or dyslexia-associated processing strengths that we saw in Kristen, Christopher, and James—such as their strong mechanical and spatial abilities or their strengths in spotting unusual connections.

  There must be some even more fundamental difference (or differences) in dyslexic brains that accounts for both phonological processing problems and the other patterns of challenges and strengths associated with dyslexia. Next, and in chapter 4, we’ll consider the remaining three dyslexia-related brain variations, each of which attempts to provide this more basic explanation.

  Procedural Learning

  The next key difference between dyslexic and nondyslexic brains to consider involves the procedural learning system and procedural memory.4 One of the leading experts on procedural learning and dyslexia, British psychologist Dr. Angela Fawcett, described procedural learning and its relationship to dyslexia for us in the following way: “Procedural learning is learning how to do something, and learning it to the point where it’s automatic, so you know how to do it without having to think about it. This process of becoming automatic with complex rules and procedures is much more difficult if you’re dyslexic.”

  At least half the individuals with dyslexia have significant problems with procedural learning, and as a result they’ll be slower to master any rule-based, procedural, or rote skill that should become automatic through practice. Because most basic academic skills are heavily rule and procedure dependent, problems with procedural learning can cause a wide range of academic challenges, which are often especially intense in the early grades.

  For example, most language skills require the constant, rapid, and effortless application of rules and procedures, including differentiating one word sound from another; correctly articulating word sounds and correctly pronouncing words; breaking words down into component sounds; mastering the rules of phonics underlying reading (decoding) and spelling (encoding); recognizing rhymes; recognizing how changes in the forms of words can change word meanings and functions (morphology, e.g., run, ran, running, runner, runny, etc.); interpreting how differences in sentence organization and word order can affect sentence meaning (syntax); and recognizing language style and pragmatics (the language conventions that carry important social cues).

  Many other academic skills are also rule based, such as rote (or automatic) memory of things like math facts, dates, titles, terms, or place names; memorizing complicated procedures or rules for things like long division, carrying over, borrowing, or dealing with fractions in math; sequences, like the alphabet, days of the week, or months of the year; writing conventions like punctuation and capitalization; and motor rules for forming letters the same way every time, when writing by hand, and spacing evenly between words.

  Finally, individuals with procedural learning challenges also typically have difficulty learning simply by observing and imitating others as they perform the complete, complex skill—that is, by implicit learning. Instead, they learn better when rules and procedures are broken down into small, more easily mastered steps and demonstrated clearly—a process known as explicit learning. When you realize how important procedural learning is for most basic skills, you can see why procedural learning challenges have been thought capable of producing so many of the challenges associated with dyslexia.

  Because individuals who struggle with procedural learning have difficulty learning to perform rule-based skills automatically, they must instead perform these skills using conscious compensation, or the combination of focused attention and active working memory. The drawback to this kind of highly focused processing is that if too many parts of a complex task must be performed consciously (because the basic skills haven’t been mastered to the point where they’re fully automatic), then working memory resources are very likely to be overwhelmed. Since individuals with procedural memory problems must perform many tasks using conscious processing, they will often experience working memory overload, which makes them slower and more error-prone than others on routine tasks.

  Individuals with procedural learning challenges also tend to require many more repetitions than others to master complex skills. Dr. Fawcett explains: “You can teach a dyslexic child what the rules are, and she appears to grasp them, but then the rules slip away again. We actually came up with something we called the square root rule, which means that it takes the square root longer to learn something if you’re dyslexic than if you aren’t. In other words, if it took four hours to learn something for a nondyslexic, it would take twice as long for a dyslexic; and if it took one hundred hours it would take ten times as long. So you can see how much extra work is needed to get these children to develop skills similar to other children.”

  Individuals with dyslexia and procedural l
earning challenges also tend to forget skills that they appear to have mastered more quickly than others if they don’t practice them. “Often teachers will say, ‘This child seemed to have learned this before the six weeks’ holiday, but now he’s come back and it’s gone.’ It helps to show teachers that it’s not due to a moral fault in the student or any lack of effort, but it’s really something to do with the basic learning processes. Actually, the dyslexic child is working much harder than everybody else, and this difficulty in learning and retaining rules results from a fundamental difference in the learning process. When you understand this, you realize that it’s not something the child should be ashamed of, but something he should be taught to get around, using specific strategies.”

  From a neurological standpoint, procedural learning challenges are often associated with dysfunction in the cerebellum, a small, densely packed structure at the back and bottom of the brain. Although it accounts for only 10 to 15 percent of the brain’s weight, the cerebellum contains nearly half the brain’s impulse-conducting cells, or neurons. Although it was long thought to be involved primarily in helping with motor (or movement-based) functions, within the past decade scientists have come to realize that the cerebellum plays a critical role in most skills that become automatic through practice—whether those skills involve movement, language, “internal speech,” working memory, or other aspects of attention.

  There is now a wealth of evidence that at least half of all individuals with dyslexia experience difficulties with procedural learning. Typically, these individuals also show signs of mild cerebellar dysfunction on exam, such as low muscle tone; poor motor coordination; and difficulties with sequencing, timing and pacing, and time awareness.

  This high incidence of procedural learning challenges in individuals with dyslexia has led Angela Fawcett and her collaborator, psychologist Roderick Nicolson, to propose the procedural learning theory of dyslexia, which posits that many of the findings of dyslexia are due to challenges with procedural learning. One of the great strengths of this theory is that it explains many of the symptoms commonly found in dyslexia that don’t obviously relate to phonology or language, like challenges with motor control and coordination. We’ve found the procedural learning theory to be especially helpful for understanding and troubleshooting the learning challenges of individuals with dyslexia who show features like low processing speed scores on WISC IQ tests, very slow work output, motor problems with handwriting or eye movement control, problems with rote memory for things like math facts, more extensive problems with syntax or expressive language, special difficulties with sequencing, and poor time awareness and estimation.

  Another strength of the procedural learning theory is that it predicts some of the advantages that we often observe in individuals with dyslexia. For example, while poor automaticity in routine skills makes many individuals with dyslexia slower and less efficient on routine tasks, it also forces them to approach these tasks with a greater “mindfulness” or task awareness and to really think about what they’re doing. As a consequence, we’ve found that individuals with dyslexia often innovate and experiment with routine procedures, and in the process find new and better ways of doing things. In contrast, individuals with strong procedural learning abilities quickly learn to perform tasks in just the way they were taught, so they often perform these tasks without having to think about them. As a result, they less often feel the need to innovate. This kind of “flip side” benefit to dyslexic processing is just what we would expect to see from any full explanation of dyslexia.

  Still, there are several drawbacks to the procedural learning theory as a complete explanation of dyslexia. Many individuals with dyslexia do not show clear procedural learning challenges, and many of the dyslexic advantages described in later chapters can’t easily be attributed to increasing task mindfulness. For these reasons, a full explanation for both dyslexic challenges and the strengths must depend upon an even more fundamental feature of dyslexic brains. In the next chapter, we’ll look at two variations in brain structure that may provide this deeper explanation.

  CHAPTER 4

  Differences in Brain Structure

  In 1981, Dr. Roger Sperry was awarded the Nobel Prize for his discovery that the brain’s two halves, or hemispheres, process information in very different ways. Ever since, a steady stream of books and articles have popularized the idea that there are distinctive “right-brain” and “left-brain” thinking styles and that individuals can be primarily “right-brained” or “left-brained” in their cognitive approach.1 While these views of brain function are highly oversimplified, they still contain a good deal of truth: the brain’s two hemispheres really do process information in very different ways.

  As a rough generalization, the brain’s left hemisphere specializes in fine-detail processing. It carefully examines the component pieces of objects and ideas, precisely characterizes them, and helps to distinguish them from each other. The right hemisphere specializes in processing the large-scale, big-picture, “coarse,” or “global” features of objects or ideas. It’s especially good at spotting connections that tie things together; at seeing distant similarities or relationships between objects or ideas; at perceiving how parts relate to wholes; at determining the essence, gist, or purpose of a thing or idea; and at identifying any background or context that might be relevant for understanding the objects under inspection.

  We can roughly summarize the functional differences between left and right hemispheres by saying that they specialize respectively in trees and forest, fine and coarse features, text and context, or parts and wholes.2 These differences show up in important ways in the brain’s various processing systems. Consider vision: when looking at an object, the left hemisphere perceives fine details and component features, but it’s poor at “binding” those features together to “see” the larger whole. For example, the left hemisphere can recognize eyes and ears and noses and mouths, but it’s poor at recognizing faces. Similarly, it can see windows and doors and chimneys and shingles, but it’s poor at seeing houses. To perceive these larger patterns, the left hemisphere requires big-picture processing help from the right.

  We’re raising this topic because several kinds of evidence suggest that individuals with dyslexia differ from nondyslexics in the ways they use their brain hemispheres to process information. In particular, a growing body of research suggests that individuals with dyslexia use their right hemispheres more extensively for many processing tasks than do nondyslexics. Differences of this type have been shown for many auditory, visual, and motor functions, and some of these differences play a role in reading and language.

  This dyslexia-related difference in the division of labor between the brain’s hemispheres is the third variation we’ll examine in our search for the factors underlying dyslexic strengths and challenges.

  Are Individuals with Dyslexia Really More “Right Brained” Than Nondyslexics?

  Several prominent writers have observed that individuals with dyslexia often show a distinctly “right-brained style” or “flavor” in the ways that they process information. A particularly strong case for this connection has been made by author Thomas G. West in his marvelous book In the Mind’s Eye.3 West—who himself is dyslexic—suggests that this right-sided processing pattern may be directly related to the visual and spatial talents shown by many individuals with dyslexia.4

  Scientists have also found that individuals with dyslexia use their right hemispheres more extensively for reading than do nondyslexics. This difference was first demonstrated in the late 1990s by Drs. Sally and Bennett Shaywitz at Yale, who used a brain scanning technique called functional magnetic resonance imaging (fMRI) to identify the brain areas that become active as individuals with dyslexia and nondyslexics read.5 Reading expert Dr. Maryanne Wolf summed up the results of this work by writing, “The dyslexic brain consistently employs more right-hemisphere structures [for reading and its component processing activities] than left-hemisphere struct
ures.”6

  While this increased right-hemispheric processing may at first appear to involve a “rightward shift” from the normal left-sided pattern, it actually reflects the absence of the usual “leftward shift” that occurs as individuals learn to read. Dr. Guinevere Eden and her colleagues at Georgetown University have shown that most beginning readers use both sides of their brain quite heavily—just like individuals with dyslexia. It’s only with practice that most readers gradually shift to a largely left-sided processing circuit.7

  Individuals with dyslexia have a much harder time making this shift to primarily left-sided, or “expert,” processing. Without intensive training they tend to retain the “immature” or “beginner” pathway, with its heavy reliance on right-hemispheric processing.

  This dyslexic tendency to retain the largely right-sided “beginner” pathway raises two important questions. First, why do individuals with dyslexia show this persistence of heavy right-hemisphere involvement? And second, what are the consequences of this persistence for dyslexic thinking and processing?

  In approaching the first question, it’s important to recognize that the reading circuit isn’t the only brain pathway in which a right-to-left processing shift is produced by practice and experience. Transitions like this are seen in many brain systems, and they are thought to reflect our changing processing needs as our skills increase. The general idea goes like this.

  When we attempt a new task, our right hemisphere’s coarse or big-picture processing helps us recognize the overall point or essence of the task, so we don’t get lost in the details. It also helps us recognize how the new task may be similar to tasks we’ve learned before, which helps us problem-solve and fill in details we miss. In these ways, the right hemisphere’s top-down or big-picture processing is ideal for our early attempts to stumble through processes we’re still fuzzy on. It’s also invaluable when we try to tackle other tasks for which we lack the automatic skills to perform quickly and efficiently.