Understanding the Different Types of Dyslexia: How the Science of Reading and Orton-Gillingham Address Diverse Reading Challenges
Dyslexia is one of the most studied learning differences in the world, yet it is still widely misunderstood. Traditionally, dyslexia has been seen as a one-size-fits-all condition characterized by difficulty reading. However, modern neuroscience and the Science of Reading have revealed that dyslexia is multifaceted, with several subtypes, each rooted in different cognitive challenges.
Understanding the specific type of dyslexia a child has is essential for crafting effective interventions. In this article, we’ll explore the common types of dyslexia, how they affect reading development, and how Orton-Gillingham and other structured literacy approaches address each one.
What Is Dyslexia?
Dyslexia is a neurobiological language-based learning difference that primarily affects accurate and fluent word recognition, spelling, and decoding. It is not a problem of intelligence, vision, or effort. According to the International Dyslexia Association, it results from a deficit in the phonological component of language.
The Science of Reading shows that skilled reading requires both decoding (sounding out words) and language comprehension (understanding what the words mean). Dyslexia primarily interferes with the decoding process but can also affect other areas depending on the subtype.
Common Types of Dyslexia
1. Phonological Dyslexia (Classic Dyslexia)
What it means:
Phonological dyslexia is the most common and widely recognized type. Children with this type struggle to hear, isolate, and manipulate individual sounds (phonemes) in words. This affects their ability to decode—breaking down words into sounds and blending them back together.
Example:
The word “cat” might be read as “cot” or “cap” because the child struggles to identify and blend the /k/ /ă/ /t/ sounds.
How Orton-Gillingham helps:
Orton-Gillingham (OG) is rooted in explicit, sequential, and multisensory instruction in phonemic awareness and phonics. OG teaches students to map phonemes to graphemes (sounds to letters) step by step using multisensory tools (e.g., tracing letters in sand while saying the sound). Phonological dyslexia responds very well to OG because it directly remediates the core phonemic awareness deficit.
2. Surface Dyslexia (Orthographic Dyslexia)
What it means:
Children with surface dyslexia struggle with sight word recognition—reading words that don’t follow standard phonetic rules. These children often rely heavily on decoding, even for irregular words like “said,” “one,” or “laugh.”
Example:
A child might decode “said” as /s/ /ă/ /i/ /d/ because they don’t recognize it as a whole word with an irregular spelling.
How Orton-Gillingham helps:
OG includes orthographic mapping strategies, helping students store whole word patterns in long-term memory through repeated exposure, spelling practice, and multisensory drills. Irregular words are taught through heart word techniques (marking the “tricky part” of a word to remember it by heart). Structured literacy practices support orthographic processing through consistent review and visual drills.
3. Rapid Naming Deficit Dyslexia (RAN Type)
What it means:
This type affects processing speed, especially the ability to quickly name letters, numbers, colors, or objects. Children may know the sounds but retrieve them slowly, affecting fluency.
Example:
A student can sound out words but reads them very slowly and laboriously, affecting overall comprehension and flow.
How Orton-Gillingham helps:
While OG is not a fluency program per se, it incorporates fluency-building strategies like timed drills, repeated reading, and cumulative review of previously learned patterns. Integrating automaticity drills, such as rapid letter naming or “decoding sprints,” helps improve speed and retrieval over time. Pairing OG with programs like Read Naturally or REWARDS can also accelerate fluency.
4. Double Deficit Dyslexia
What it means:
This is a combination of both phonological dyslexia and rapid naming deficits, making it the most severe type. These children have trouble both decoding and retrieving words quickly.
Example:
The child struggles to sound out words and reads slowly even when they know the correct sounds. They may also struggle with spelling and reading comprehension due to overall cognitive load.
How Orton-Gillingham helps:
A highly structured OG approach provides repeated, explicit instruction in phonemic awareness, phonics, and fluency. Since double deficit dyslexia requires more intensive intervention, OG programs may need to be paired with daily fluency practice, automaticity drills, and oral language exercises to strengthen both decoding and naming speed. Progress is often slower but highly effective with consistency.
5. Acquired Dyslexia
What it means:
Unlike developmental dyslexia, acquired dyslexia results from a brain injury, stroke, or illness affecting the language-processing centers of the brain.
Example:
A child who once read fluently may begin to exhibit signs of dyslexia after a concussion or neurological event.
How Orton-Gillingham helps:
OG can be adapted as part of a rehabilitative therapy plan, especially when used alongside speech-language therapy. The step-by-step reintroduction of sound-letter associations, spelling patterns, and word recognition helps rewire reading pathways in the brain.
Less Common Types of Dyslexia
6. Linguistic Dyslexia (Comprehension Type)
What it means:
This type affects a child’s ability to understand the meaning of words, sentences, or stories. It’s less about decoding and more about language comprehension—often tied to oral language deficits or mixed receptive-expressive language disorders.
Example:
A student may read fluently but struggle to answer questions about what they just read or retell a story in sequence.
How Orton-Gillingham helps:
Though OG focuses primarily on decoding, many OG-based programs include language comprehension components such as vocabulary development, sentence structure, and background knowledge. Paired with the Simple View of Reading (Decoding × Language Comprehension = Reading Comprehension), instruction is adapted to strengthen oral language skills alongside reading mechanics.
7. Spatial Dyslexia (Visual-Spatial Processing Disorder)
What it means:
Sometimes confused with dyslexia, this type is more about visual-spatial orientation—difficulty tracking lines of text, maintaining left-to-right directionality, or distinguishing similar letters (e.g., b/d, p/q). This is sometimes seen in children with coexisting conditions like dyspraxia or nonverbal learning disabilities.
Example:
The child may skip lines, reverse letters, or mix up word order while reading.
How Orton-Gillingham helps:
OG’s multisensory techniques (e.g., skywriting letters, using sand trays, finger-tracing) help reinforce proper letter formation and spatial orientation. Visual and tactile supports (highlighting, color overlays, reading windows) and explicit directionality instruction (left-to-right scanning, finger-tracking) are integrated to improve spatial awareness during reading and writing.
Why Orton-Gillingham Works for All Types
The power of Orton-Gillingham lies in its:
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Multisensory instruction – engages visual, auditory, kinesthetic, and tactile pathways.
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Explicit and systematic approach – introduces concepts in a carefully sequenced order.
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Cumulative review – ensures mastery before moving on.
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Individualized instruction – adapts to the learner’s needs and pace.
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Focus on phonemic awareness, phonics, fluency, vocabulary, and comprehension – all aligned with the Science of Reading.
Whether a child has classic phonological dyslexia, a rare subtype, or a complex combination, OG and structured literacy provide a proven path to reading success.
Final Thoughts: Matching the Method to the Mind
Every child with dyslexia is unique. Some may need intense decoding instruction, while others need help recognizing whole words or building fluency. A comprehensive evaluation, ideally involving a reading specialist or neuropsychologist, is key to identifying the subtype(s) of dyslexia.
When instruction is grounded in the Science of Reading and delivered through a program like Orton-Gillingham, children with dyslexia can—and do—learn to read. With the right support, practice, and encouragement, they don’t just catch up. They thrive.