different kinds of dyslexia

Have ever seen an article or heard someone say that they or their child has a particular type of dyslexia? Some names I’ve heard are:

  • dysphonetic dyslexia
  • auditory dyslexia
  • dyseidetic dyslexia
  • visual dyslexia
  • double deficit dyslexia
  • attentional dyslexia

Being on the alert for false claims about dyslexia, I set about researching these ‘different kinds of dyslexia’ to see if they are helpful for parents to understand.

Factors That Can Contribute to Dyslexia

The idea that dyslexia is fundamentally an issue with phonemic awareness or phonological processing (the ability to hear and manipulate the individual sounds of language) has dominated our understanding of dyslexia for years.  However, this particular type of weakness is not the only factor that can contribute to dyslexia.

Other factors that can contribute to dyslexia:

  • Attention
  • Orthography, or the ability to recall spelling patterns.
  • Rapid automatized naming (RAN), or the quick naming of colors, objects, letters or digits.
  • Perceptual or processing speed – visual scanning speed
  • Working memory or recalling and rearranging information

No two people with dyslexia will have the exact same learning profile.  Dyslexia can be mild, moderate or profound and can be caused by several different specific weaknesses or combination of weaknesses.

3 Subtypes of Dyslexia

In the book Proust and the Squid, Dr. Maryanne Wolf theorized that there are 3 subtypes of dyslexia.

Phonological Processing Deficit

The most common of these subtypes is a deficit in phonological processing and this impacts the ability to decode/sound out words.  This particular type of weakness has also been called Dysphonetic Dyslexia or Auditory Dyslexia.

People with this subtype of dyslexia simply have a harder time processing the individual sounds that make up spoken words and they have a harder time mapping the sound, or phoneme, to the written letter, or grapheme.

Signs of Phonological Processing Deficit:

  • Have at least average listening comprehension and oral vocabularies
  • Have problems with word recognition that usually center upon phonemic awareness and word decoding
  • Often have fluency problems involving inaccurate or non-automatic word reading
  • Have reading difficulties that often emerge early (i.e., K-3)
  • Reading comprehension problems are related entirely to word reading
Help for Students With Phonological Processing Weaknesses:
Kids with Phonological Processing weaknesses benefit from explicit, systematic instruction in phonics  – also known as the Orton-Gillingham Approach.  They often benefit from fluency activities targeting automaticity of decoding.

Rapid Naming Deficit

The second subtype of dyslexia, according to Dr Wolf, is a deficit in rapid naming.  This particular set of weaknesses has also been referred to as Dyseidetic Dyslexia or Visual Dyslexia.

People with this subtype of dyslexia will have normal phonological processing, but their fluency and comprehension will be affected by the retrieval of language based information. These are the people that will have problems with word recall, either by saying the wrong word or the word is “on the tip of their tongue”. This affects fluency because it takes longer to retrieve language information. This also affects comprehension because sometimes the retrieved language information is wrong because retrieving the wrong definition or wrong word can change meaning.

Signs of Rapid Naming Deficit:

  • Have at least average word recognition and phonological skills  
  • Have reading comprehension problems that frequently involve listening comprehension or oral vocabulary knowledge 
  • Listening comprehension usually not low enough for speech and language services eligibility.  
  • Have no history of early decoding problems 
  • Any fluency problems tend to be based in language, not single word reading 
  • Difficulties often, though not always, emerge later in schooling (around 4th grade and up)
Help for Students With Rapid Naming Weaknesses:
Students with rapid naming weaknesses benefit from instruction targeting the their specific comprehension weaknesses (e.g., vocabulary, background knowledge, pragmatic language.) Vocabulary and language comprehension development are more likely to improve fluency than are interventions focused on automaticity of decoding. These students may also benefit from slow reading as a strategy to improve comprehension.  Click here to read more about strategies for building fluency and comprehension.

Double Deficit Dyslexia

The third subtype of dyslexia is double deficit: deficits in both phonological processing and rapid naming. This subtype is the least common and the hardest to remediate.

Signs of Double Deficit Dyslexia:

  • Have difficulties with word recognition and phonological skills
  • Have poor reading comprehension that is only partly accounted for by decoding (e.g., poor comprehension may occur even in text the child decodes well)
  • Listening comprehension or oral vocabulary also often weak (but again, not necessarily low enough for speech and language services)
  • Fluency frequently is poor due to problems in both word reading and language comprehension
  • Difficulties tend to emerge early in schooling (K-3) due to problems with word reading, but may persist even after remediation of decoding skills, because there is an additional comprehension component to the child’s reading difficulties
Help for Students With Double Deficit Dyslexia:
Students with Double Deficit Dyslexia benefit from both of the above types of instruction.  

Research from neuroscientists at MIT and Stanford/UCSF now supports Maryanne Wolf’s theory on the 3 subtypes of dyslexia by showing different patterns of brain activation when reading and rhyming words. Children with a deficit in phonological awareness only, rapid naming only, or difficulty in both areas each showed different patterns of brain activation and connectivity as revealed by MRI.

What does all of this mean to parents?

I have always noted among my own kids that some of them struggled more with auditory processing (as in the first subtype) and some struggled more with visual processing (the second subtype).  I have also noted that my more profoundly dyslexic son struggled in both areas.  Ultimately, all of the subtypes respond to researched based intervention found in programs based on the Orton-Gillingham approach, like All About Reading, which also includes comprehension instruction.

Do we need to get our kids tested?  Read this post on when and how to get your kids tested for dyslexia.

How about you?  Have you heard of different kinds of dyslexia?