Diagnosing dyslexia is complicated, because there are other factors that can cause reading failure. Many children (up to 40%) show some signs of dyslexia, but not all are dyslexic. For example, there is the case of Emma.
Emma was a second grader experiencing serious reading failure. She entered my reading program in the summer. She progressed quickly, so quickly she outpaced other students. On phonemic awareness activities, she developed a sophisticated understanding of sound. By the end of summer, Emma was still in need of an intervention, but she went from reading, “Mel sat on the jet.” to “Mel flew through the starlit sky on the zooming jet.”—a big leap in less than three months. Was Emma dyslexic? It’s possible, but unlikely.
Without good research-based reading instruction, according to researcher and literacy expert Jeanne Chall, 40% of children will struggle with reading, but only about 4-17% are dyslexic (Dehaene, 2009).
Many experts believe the estimates of dyslexia to be too high. Dyslexia and reading experts Reid Lyon, Jeanne Chall and John Shefelbine believe 5% of children are dyslexic and the rest are children that suffered through a curriculum that doesn’t match their learning needs. These researchers believe the rate to be 5% because with research-based instruction, only 5% of children will struggle with reading, and these children are absolutely without a shred of doubt dyslexic.
Yet, some estimates of dyslexia are at 20%. Most dyslexia-based companies claim a dyslexia rate that is on the upper-end, some even claiming 30% of the population is dyslexic.
In truth, no one knows the exact rates of dyslexia. No one can (or should) claim a dyslexia rate with confidence.
With poor reading instruction that emphasizes memorization and giving children pictures to lean on, many, many children will be struggling readers. However, most of these struggling readers would’ve performed fabulously in reading if they had only been given research-based instruction.
Family History of Dyslexia
Although dyslexia rates vary widely, we know dyslexia is not a social construction. Dyslexia runs in families. It is heritable and genetically-based. If a child has dyslexia, there’s a 50% possibility his sibling is dyslexic too. Any formal reading evaluation “should begin with a thorough family history of reading difficulty” [Assessment for Dyslexia, p. 63 in Dyslexia Theory and Practice, 2004) If mom and aunt Martha suffered through reading failure, dyslexia probably runs in the family.
Rate of response to Research-Based Reading Intervention
Any good diagnosis should consider the school’s method of instruction and ask, “Has the child had access to appropriate instruction? [Berninger & Robert Abbott].” If the child has had access to a research-based reading intervention, and still acquires reading relatively slowly, then he’s likely dyslexic. A dyslexic child will not make big leaps in reading acquisition.
Decoding and Intelligence are Not Correlated
There is no correlation between intelligence and decoding abilities. The struggling readers and dyslexic readers in my San Diego Reading Intervention program are bright and talented. THERE IS NO EVIDENCE THAT DECODING AND INTELLIGENCE ARE CORRELATED—I loathe this harmful and false idea. It’s really unfortunate that our culture associates the ability to decode with intelligence. It’s simply not true.
This myth puts the blame on the child.
Many seek a dyslexia diagnosis to absolve the child, but most struggling readers are NOT AT FAULT for their reading failure. Don’t buy into the myth that struggling readers are less intelligent or lazy. Dyslexic or not, 40%* of children will struggle with reading (without research-based instruction)—most are bright children that were expected to learn in a way that doesn’t work for them. THAT’S A LOT OF CHILDREN!!!
The narrative for all struggling readers, dyslexic or not, should go something like this:
“I thought I was stupid, but then I received an intervention that worked for me. Someone tried to teach me the wrong way. It’s like someone trying to teach a left-handed person how to throw with his right hand. He throws poorly and thinks he sucks at throwing. But then someone comes along and teaches him to throw with his left hand. After awhile, he realizes he’s a fantastic thrower. That he was simply a left-handed person trying to learn the right-handed way. I realize now that I learn in a unique way. Even though my initial reading struggles were hard, I showed perseverance, kept trying, worked-hard and now I can read!”
Berninger, V. W. Abbott, R. D. 1994. Moving Beyond aptitude-achievement discrepancies to failure to respond to validated treatment protocols. In Frames of Reference for the Assessment of Learning Disabilities.
Dehaene, Stanislaus (2009). Reading in the Brain: The New Science of How we Read.
Uhry, Joanna & Clark, Dianna (2004). Dyslexia Theory & Practice of Instruction.