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Full Course Details: Public course page
Learn more about our guest: Penny Stack OTD, OTR/L, CHT, HWC
Agenda
Intro (5 minutes)
Breakdown and analysis of journal article (5 minutes)
00:00:00 Intro
00:01:08 OT Potential Podcast Intro
00:03:24 History of dyslexia
00:04:33 Challenges of the current state of dyslexia
00:06:04 New theories of dyslexia
00:08:34 One theory to unite them all?
00:09:14 Strengths of people with dyslexia
00:12:36 Article conclusion
Discussion on practical implications for OTs (50 minutes)
00:13:49 Intro to Penny Stack
00:15:24 Penny’s journey into working with dyslexia
00:18:23 Article impressions
00:21:37 Describing dyslexia to clients
00:23:36 OT understanding of dyslexia
00:29:15 OT assessments and dyslexia
00:32:14 OT outcomes and dyslexia
00:46:20 OT intervention and dyslexia
00:50:01 Team approach to dyslexia
00:55:18 More dyslexia OT resources
00:57:14 How does OT need to change?
Supplemental Materials
- Comparing the effects of two education-based intervention programs on visual perception processes of children with developmental dyslexia
- The current status of the magnocellular theory of developmental dyslexia
More Resources for OTs supporting dyslexia
See all assessments in our OT Assessment Guide
- Beery-Buktenica Developmental Test of Visual-Motor Integration | Sixth Edition (BEERY™ VMI)
- Jordan Left-Right Reversal Test
- Test for Information Processing Skills
- Test of Visual Perceptual Skill (non-motor) (TVPS-4)
Article Review
Read Full Text: Theories about Developmental Dyslexia
Journal: Brain Science
Year Published: 2023
Dyslexia is the most common form of neurodivergence.
It affects around 20% of the population, meaning nearly every occupational therapy professional will have an individual with dyslexia on their caseload at some point. And yet, not enough OT-specific research and resources have been devoted to supporting us in our work with this population.
Today, we look at a leading theory of dyslexia that is essentially a call to action for OTs to reexamine how needed our skills truly are.
This theory proposes that dyslexia is rooted in a sensory processing difference (hello, OT!), thereby pushing us to embrace a strengths-based treatment approach.
To help us unpack what this means for your practice, next week we will welcome to the podcast Penny Stack, OTD, OTR/L, the founder of DyslexiaRx.
Quick intro to this commentary
This paper was written by John Stein, an Oxford professor who has spent much of his career exploring the neurobiological basis of dyslexia.
In reading this paper, you’ll feel like you are dropping into a longstanding, heated debate about dyslexia. You are! (FYI: This article helped me understand the other side of the argument.) Ultimately, though, I found Stein’s summary of the science behind dyslexia helpful, and I hope you chime in with your thoughts in the comments below!
Brief history of dyslexia
Meaning “disordered words” in Greek, the term “dyslexia” was coined in 1884. Back then, it applied to post-stroke patients who had lost the ability to read and spell—but whose speech and oral comprehension remained intact. We now call this acquired dyslexia.
A few years later, Hinshelwood and Morgan speculated that there may be another form of dyslexia unrelated to stroke. In developmental dyslexia, they explained, individuals developed normal speech and comprehension abilities—but found reading unusually difficult.
They proposed that this selective deficit signified that reading must employ a distinct anatomical pathway. They also recognized that developmental dyslexia tended to run in families.
Newer science and imaging studies have continued to bear out this understanding of dyslexia. And, for over a century, developmental dyslexia was recognized as a useful diagnosis—until recently.
Challenges with the current state of dyslexia
The author of the current paper argues that for about a century, dyslexia was in the domain of the medical model. After that, it transitioned into the domain of educational psychology. This coincided with a linguistic revolution that centered on the nature of “phonemes.”
Hang with me—this is worth understanding fully!
In this view, the essence of reading is translating letters into the sounds they represent. This is a complicated process, as the acoustic sound of each letter is based on context.
While a useful principle, this heightened emphasis on phonology has cast dyslexia as a phonological deficit problem—which brings up a couple of issues:
- It does not explain WHY this problem occurs.
- Failure to master the phonological principle is inherent in all poor readers, and thus does not help differentiate dyslexia from other reading struggles.
Given these challenges, some have attempted to invalidate the diagnosis of dyslexia altogether.
But, the author argues that advancements in neuroscience and genetics continue to support the existence of dyslexia—and that properly understanding the condition could help us unearth better techniques for diagnosing and treating it.
New theories on dyslexia
The author walks through several different theories of dyslexia and the science behind each.
As you’ll see, most of these theories simply describe the differences seen in people with dyslexia. The author argues that we cannot fully comprehend the condition without having a neurological understanding of it.
Rapid automatized naming
Back in 1976, researchers discovered that dyslexia could be distinguished from other reading difficulties by slowness at rapid automatized naming (i.e., being able to read out loud—as fast as possible—lists of letters, numbers, or pictures). The problem was not the reader’s inability to learn the correct phonemes; it was slowed production of the sounds. This theory paints dyslexia as a speech timing and fluency problem.
Reduced visual attention span
Increasing evidence shows that people with dyslexia have slower and less accurate visual attention when reading.
Visual stress
Another theory is that the appearance of text overstimulates the visual system of those with dyslexia, causing visual discomfort. This may be why some people with dyslexia prefer to view text through colored filters.
Sensory signal processing
Compared to typically developing readers, people with dyslexia appear to be particularly poor at detecting stimuli in the presence of irrelevant distractors.
Sensory temporal processing
People with dyslexia appear to have timing difficulties with auditory processing, visual processing, or both.
Accurate timing of when the eyes land on each letter is essential in reading, but this is an extremely complex process that may be impaired in individuals with dyslexia. Precise timing when hearing phonemes is a similarly complex process that also may be difficult for people with dyslexia.
One idea to unite them all: the magnocellular theory
The author believes the sensory processing deficit that is present in people with dyslexia can be traced to magnocelluar cells, which form a distinct visual pathway. He asserts that these cells are particularly important for the proper timing of eye movements (i.e., moving your eyes across a page). And, in dyslexia, this particular system is impaired.
You can read his full theory here.
Understanding the strengths of people with dyslexia
Okay, this is where the paper gets really interesting!
Running parallel to the magnocellular pathway is the parvocellular pathway. These cells are smaller and more connected, processing different types of visual and auditory information than the larger magnocellular cells.
The author believes that when the magnocellular pathway is impaired, the parvocellular pathway compensates—giving those with dyslexia unique visual, auditory, and cognitive strengths. So, while people with dyslexia may struggle to hold their gaze on small, crowded, black-and-white print, they have shown exceptional skill in:
- Distinguishing between red and green
- Seeing a high level of detail in the periphery of their visual field
- Quickly deciding whether drawings of objects are physically possible
- Identifying shapes in ambiguous figures
- Remembering and producing designs and complex figures
- Recreating and navigating virtual environments
A lot of research has focused on the deficits of people with dyslexia, so strengths like the ones above have been far less studied. But after decades of focusing on this diagnosis, the author has come to believe the following:
People with dyslexia are drawn to creative and artistic professions.
People with dyslexia are overrepresented in a specific set of professions, including:
- Aesthetic and artistic vocations
- Entrepreneurial business
- Practical engineering
- Mathematics and computing
In these fields, there is a long list of exceptionally talented people with dyslexia (or who likely had dyslexia), including: Caesar Augustus, Leonardo da Vinci, Einstein, Winston Churchill, and Steven Spielberg.
They may have a more “holistic vision.”
People with dyslexia may be able to pick up more visual detail, over a wider area, more quickly than people with ordinary brains. This is also called helicopter vision, which means they may be able to imagine a whole scene from above in all of its visual detail.
They may have a unique appreciation of music.
A proliferation of parvocellular cells may be present in the auditory system of people with dyslexia as well. While they may have difficulty with timing and picking up rhythm, they are better at detecting the combination of components in a musical chord.
This holistic perception of sound seems to bestow on them a better appreciation of the timbre and emotional tone of music.
They may have a unique abstract cognitive style.
While this final observation is difficult to test, the author believes that people with dyslexia have an unusually holistic way of thinking.
As such, he believes they are especially good at:
- Judging personality
- Seeing every element of a problem simultaneously
- Lateral thinking, creativity, and inventiveness
Conclusion
The author believes that various theories of dyslexia converge on an underlying, imprecise signaling by magnocellular neurons—which in turn, impacts the timing of visual and auditory processing. But while this may cause difficulties with reading, people with dyslexia may also have a parvocellular proliferation—leading to exceptional creative, artistic, entrepreneurial, communication, and engineering talents. These capabilities should be valued, prioritized, and nurtured.
He ends with this quote about people with dyslexia:
The unsustainability of the modern world needs their imagination, innovation, and creativity to help us survive.
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