A Nosology for Learning Disabilities: A Foundation for the Bridge Between Research and Practice.

A Nosology for Learning Disabilities: A Foundation for the Bridge Between Research and Practice.

Remembering math facts was difficult for me. It still is. In elementary school I was a basket case; I had difficulty learning how to read and couldn’t remember the multiplication tables. Fortunately, not all of my educational experiences were as difficult as elementary school; I didn’t get better, school got easier. My early deficits in math did not appear to be directly related to the later educational demands. For instance, I eventually obtained an undergraduate degree in engineering; math facts were a problem, math concepts were a strength. By contrast, my early deficits in reading, although always changing and maturing, follow me to this day.

Is math as important to the average person as reading? The way we test children would seem to indicate that we value both equally. Scores on high stakes testing, SATs, etc., usually provide a reading and an equally visible math score. However, unless you are an accountant, physicist, or engineer, the most math the average person uses is learned by the 3rd or 4th grade, and we use computers and even cell phones to do the simplest math calculations for us. When was the last time you needed to calculate the hypotenuse of a right triangle? However, math is more than calculating; experience with math helps with organization, logic, deduction, and thinking in general. There are math concepts that help us appreciate and create art, write music, and tell a story. Math is complicated. It is a discipline, it is an art, it is a way of thinking, seeing, hearing, and doing. Math is not just a score on the SAT; it is a functional skill that affects our ability to carry out the demands of the culture in which we live.

Reading, as it turns out, appears to have been a good place to start looking for a pattern to understand learning disabilities in general because it seems to be relatively linear. However, as this issue ofPerspectives will clearly indicate, the research in reading and dyslexia is not a reliable analogue for understanding problems in math. As pointed out by John Woodward in the Theme Editor’s Summary, math is a “varied” discipline that requires “differentiating instruction based on the varied needs of learners.” What that means to me is that, unlike dyslexia, there are many forks, crossroads, and possiblecul-de-sacs on the road from neurobiological deficit to functional impact when it comes to understanding why some children have difficulty with math.

For instance, when discussing the cognitive processes involved in solving math problems, terms are used such as sequencing,directionalityworking memory, divergent thinkingreasoning ability,conceptual understandingself regulationstrategic thinking, andproblem solving. What are the relationships between and among these terms and the processes they describe? Is term A the same as term B? Does term A lead to term B, which leads to term C? Or does term C lead to both A and B with A and B having a merely correlational and not a causal relationship? In order to explain these differences and inconsistencies in math and other specific learning disabilities, it is necessary that there exist basic rules (a nosology and taxonomic structure) upon which we can all agree.

In comparison, the research into reading has determined that most reading problems result from a neurobiological deficit in the “phonological component of language” that leads to “difficulties with accurate and/or fluent word recognition and poor spelling and decoding abilities”[1] that interfere with efficient reading ability and ultimately the acquisition of skills necessary for adaptive functioning. The cause to effect progression from neurobiological to adaptive functioning appears sequential and linear.

Almost 15 years ago Shaywitz, et al. encouraged “the development of a unitary, empirically derived nosology . . . [that] should increase the consistency and generalizability of findings across investigations and across disciplines.”[2] The concept of learning disability without an “empirically derived nosology” or taxonomic structure will continue to produce research that is difficult to defend and generalize.

In addition to a formal scientific consensus as to a definition, it would be helpful to have an understanding that learning disabilities mature through stages like a plant, a human being, or a butterfly. If we are not aware of these stages of development we risk viewing each stage as a separate phenomenon without a link to what comes before or after; the butterfly is not seen as connected to the caterpillar. Scientific literature in the field often uses different terms to represent a similar finding or concept and sometimes the same term to represent very different concepts. Research also, without apparent awareness, often appears to be examining separate stages of the same phenomenon.

Like the western United States in the 1820s, I believe that the study of learning disabilities currently suffers from relative lawlessness. (Of course, there is peace in some territories in the field thanks to “Wyatt” Lyon, “Bat” Fletcher, “Calamity” Moats, “Wild Bill” Torgesen, and others who promote law enforcement.) However, for the majority of us many questions remain. Are learning disabilities identified by their cause or their effect? Are variations in neurobiological development interrelated, e.g., weak phonological processing and strong visual spatial ability? Does a learning disability exist if it has no functional consequence? Is a learning disability, in fact, even a disability, as we usually use that word, or simply a normal and predictable variation within the human condition? Many are afraid that if it is accepted that most of those labeled as having a learning disability are simply experiencing a variation of normal, the concept of learning disabilities will cease to exist. In fact, treating variations of normal is big business, e.g., cosmetic surgery, braces, hair loss remedies, skin care. What about eye glasses, hearing aides, and joint replacements? If we only treated that which was considered below a normally occurring range of functioning, we would all unnecessarily be forced to suffer disorders that were simply considered a variation of normal.

A generally recognized nosology for learning disabilities would provide the scaffold necessary to organize the knowledge that we are gathering in such a way as to support an indisputable and unassailable foundation for the bridge from research to practice. Without a working definition and nosology the Tower of Babel in which we currently work in the field of learning disabilities will continue to exist and meaningful communications and progress will continue to be problematic.

G. Emerson Dickman, President

[1] Lyon, G. R., Shaywitz, S.E., & Shaywitz, B.A. (2003).  A definition of dyslexia.  Annals of Dyslexia, 53, 1-14.


[2] Shaywitz, S.E., Fletcher, J.M., Shaywitz B.A., Issues in the definition and classification of attention deficit disorder.  Topics in Language Disorder 1994; 14(4), 1-25, on p. 22.