Defining Dyslexia and Dysgraphia

The definitions for both dyslexia and dysgraphia are evolving as the research evolves. Dyslexia and Dysgraphia are language-based disabilities that impede development of reading, writing, and spelling skills. 

They are often diagnostically categorized under the umbrella term Specific Learning Disability.

Both dyslexia and dysgraphia are difficulties developing automatic word level skills. These include:

• processing and differentiating between sounds
• establishing automatic sound-to-letter connections
• learning and remembering spelling patterns
  
  

Dyslexia is primarily a difficulty in developing fast and fluent automatic sound-to-letter connections for sight word development, fluent reading, and accurate spelling, often characterized by slow decoding skills, inaccurate reading, and reading avoidance. It is primarily a deficit affecting the "phonological loop" system in the brain.

Dysgraphia is primarily a difficulty in developing fast and fluent automatic sound-to-letter connections for fluent writing and accurate spelling, often characterized by poor letter formation, poor legibility, and persistent reversal or capitalization errors. It is primarily a deficit affecting the "graphomotor loop" system in the brain, often referred to as the orthographic system.

Dyslexia and dysgraphia can occur together. Each disorder has its own set of problems, many of them overlapping. Download our checklist of indicators and watch our video on the symptoms for dyslexia and dysgraphia, as well as developmental language disorder.

 

 

Let’s unpack the official definitions. As stated, these two learning difficulties are related, sharing similar features and results, so let’s begin with the more common problem of dyslexia. 

The standard definition of dyslexia comes from the International Dyslexia Association, who held a meeting in 2002 with key researchers in the field, including Catts, Lyons, and the Shaywitzes. IDA redefined dyslexia:

"Dyslexia is a specific learning disability that is neurobiological in origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge."

There are important components of this definition:

1. "Dyslexia is a specific learning disability …"

Dyslexia is seen as a natural variation in human brain development that results in difficulty learning to read. When focused on reading and writing, it is easy to forget that all learning reflects the status of the developing brain. All literacy is language-based, all language is cognitive, and all cognition is neurological. Therefore, dyslexia is defined by neuroscientists and their discoveries.

In their book, Dyslexia, Dysgraphia, OWL LD and Dyscalculia: Lessons from Science and Teaching, Virginia Berninger and Beverly Wolf explain the brain research involved. "Broca's area [located on the left side of the brain, near the front] has been shown to house executive functions for all language systems—listening, speaking, reading, and writing" (4). Wernicke's area (located in the left temporal lobe) is the region involved in language comprehension. "According to contemporary brain imaging research, structural and functional differences occur between typical readers and writers and individuals with specific learning disabilities (SLDs) in both Broca's and Wenicke's regions" (4).

2. "… that is neurobiological in origin." 

Scientists have determined the hereditary nature of dyslexia and dysgraphia, manifested in families with various severity levels and learning struggles. Specific genes are associated with dyslexia in replicated research studies. Dr. Nadine Gaab from Harvard Medical School, has observed fetal differences in her research studies on families with dyslexia. As Berninger and Wolf explain, genes affect how the brain is wired during development, how the brain matures after birth, and the resulting impairments found in the regions of the brain needed for reading and writing. 

3. "It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities."

This definition includes key component skills needed for independent reading: fluency (the ability to read accurately, quickly, and "naturally "); automaticity (the ability to develop the sub skills needed, such as processing sounds and establishing sound-to-letter connections); spelling (the ability to establish memory for spelling patterns and words), and decoding (the word-level skills needed to independently read read text, connecting it to vocabulary and comprehension.

4. "These difficulties typically result from a deficit in the phonological component of language …"

The phonological region of the brain is listed as the primary deficit, resulting in phonological processing weakness. However, other key areas are being identified, as explained above, especially Broca's region and its relation to rapid automatic naming skills, vocabulary acquisition, and executive functioning. In addition, researcher Stanislas Dehaene writes about a region called the visual word form area: "I dubbed it the brain’s letterbox, because it concentrates much of our visual knowledge of letters and their configurations. . . . It performs highly sophisticated operations that are indispensable to fluent reading." 

5. "that is often unexpected in relation to other cognitive abilities …"

This part of the definition is the greatest area of controversy. While dyslexia may occur alone, it can co occur with many different learning problems, including those resulting in lowered IQ. However, dyslexia is not associated with IQ scores. Most specifically, there is a high incidence of dyslexia paired with Developmental Language Disabilities (DLD). Snowling et al. conducted a study in 2020 on preschool students identified as having a family risk for dyslexia. They were assessed at age 8 years, resulting in 42% diagnosed with dyslexia alone, and 58% diagnosed with both dyslexia and DLD.

6. "and the provision of effective classroom instruction."

There are children who struggle to read due to a lack of instruction or poor instruction. There are prevailing philosophies that children will learn to read "naturally, " simply by being exposed to books. There are prevailing instructional models that do not teach using explicit and systematic phonics instruction, and instead focus on reading ideals of enjoyment and minimally intrusive practice. Science supports beginning with systematic phonics instructions that includes meaningful practice in reading, writing, and spelling. The thrill results from the skill; not the other way around.

7. "Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge."

The ability to read accurately and fluently, with ease, is necessary for reading comprehension. Word-level skills must be so automatic that  higher level cognitive skills can access background knowledge, vocabulary, and inferential language skills. Reading with ease begets more reading over time, and better time spent while reading: acquiring increased vocabulary, knowledge, and understanding of our world. 

The definition of dysgraphia comes from the NIH National Library of Medicine. Dysgraphia is currently diagnosed as a cluster of symptoms, so its broad definition is as follows:

1. "disorder of writing ability"

The most common type of dysgraphia is due to "language processing deficits . . . related to inefficiency of the 'graphomotor loop,' in which the phonologic memory (regarding sounds associated with phonemes) communicates with the orthographic memory (regarding written letters)." Other language components include verbal executive functioning, which manages storage and working memory.

As we noted in our short definition above, dysgraphia is contrasted with dyslexia. According to NIH, dysgraphia results from a “two-way dysfunction of the phonologic loop”—the information highway that communicates between orthographic (letter) and phonologic (sound) processes.

4. "difficulty in acquiring writing skills despite sufficient learning opportunity and cognitive potential" 

Both disorders are persistent, even though students are exposed to reading and writing instruction. This is because dysgraphia is also neurobiological in origin. 

Berninger and Wolf describe the region in the back of the brain responsible for word form memory, "where spoken and written words are coded into memory for further processing . . . not only in phonological coding . . . but also in orthographic coding." In other words, children with dyslexia and/or dysgraphia struggle to develop the automatic sound-to-symbol relationships needed for writing, and the word form memory needed for spelling. Poor automaticity skills interrupt reading and writing fluency, as well.

Dehaene explains why children with dysgraphia struggle with capital versus lower case usage, as well. Again, the "letterbox" area of the brain is responsible for merging sound-to-letter information in a smooth and seamless manner. Dehaene writes, "the letterbox is the first visual area that recognizes that 'READ' and 'read' depict the same word by representing strings of letters invariantly for changes in case, which is no small feat if you consider that uppercase and lowercase letters such as 'A' and 'a' bear very little similarity."

The Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5) includes both dyslexia and dysgraphia under the category of "specific learning disorder." Because they are not defined as separate disorders, parents are often confused when their children receive this more general diagnosis. 

Much research has been done to understand not only the problem, but how to provide robust treatment. There are professionals who can help. At Rooted in Language, we want to equip all caregivers and educators with the knowledge and tools they need to provide the best intervention. Begin by reading our RiL Methods, where you will learn more about our approach and the science behind our methods. Then take our Placement Quiz to learn where to begin. You can always schedule a coaching session to discuss your child’s particular needs or better understand their diagnosis and receive guidance on developing a plan and path forward.

Our mission is to help every child, especially those who struggle, to become the best readers and writers they can be!

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Citations:

"Disorder of Written Expression and Dysgraphia: Definition, Diagnosis, and Management" by Chung, Patel, Nizami. (NIH, 2020)

"Dyslexia and Developmental Language Disorder: comorbid disorders with distinct effects on reading comprehension" by Snowling et al., 2020.

Dyslexia, Dysgraphia, OWL LD and Dyscalculia: Lessons from Science and Teaching, Virginia Berninger, and Beverly Wolf, 2016.

"Inside the Letterbox: How Literacy Transforms the Human Brain" by Stanislas Dehaene, 2013.

"Revisiting the Definition of Dyslexia" by Catts et al., 2024.

"Towards a Dynamic, Comprehensive Conceptualization of Dyslexia" by Wolf et al., 2024.