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Dyslexia Types: What Are the Different Types of Dyslexia?

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David is not a slow learner. In fact, according to the evaluations of several professionals he is rather intelligent. Yet he certainly has a problem, and shares his problem with millions of other children and adults.

David, according to these professionals, is dyslexic.

The term dyslexia was introduced in 1884 by the German ophthalmologist, R. Berlin. He coined it from the Greek words dys meaning ill or difficult and lexis meaning word, and used it to describe a specific disturbance of reading in the absence of pathological conditions in the visual organs. In a later publication, in 1887, Berlin stated that dyslexia, “presuming right handedness,” is caused by a left-sided cerebral lesion. He spoke of “word-blindness” and detailed his observations with six patients with brain lesions who had full command over verbal communications but had lost the ability to read.

In the century to follow the narrow definition Berlin attached to the term dyslexia would broaden. Today the term dyslexia is frequently used to refer to a normal child — or adult — who seems brighter than what his reading and written work suggest. While the term is mostly used to describe a severe reading problem, there has been little agreement in the literature or in practice concerning the definition of severe or the specific distinguishing characteristics that differentiate dyslexia from other reading problems.

The terms phonological dyslexia and surface dyslexia are generally used to describe two main types of dyslexia.

Phonological dyslexia

Synonyms for phonological dyslexia include dysphonetic dyslexia and auditory dyslexia

This type of dyslexia includes trouble breaking words down into syllables and into smaller sound units called phonemes. For example, if you say a word out loud to a child with weak phonemic skills, she can hear the word just fine and repeat it back to you. But she’ll have trouble telling you how to split it apart into the different sounds that make up this word.

Difficulties in this area can make it hard for readers to match phonemes with their written symbols (graphemes). This makes it hard to sound out or “decode” words.

One way children get tested for issues in these areas is by being asked to read fake words, like jeet. The idea is to show kids a word they’ve never come across before and see if they can sound it out.

Corinne Roth Smith lists the reading and spelling patterns of children with phonological dyslexia:

  • Difficulty discriminating between individual sounds in beginning reading instructions (occurs very seldom).
  • Difficulty processing rapid auditory inputs so that consonant sounds that cannot be sustained (p-b) are not perceived; these may then be omitted in reading.
  • Poor ability to analyze the sequence of sounds and syllables in words; consequently they become reversed in reading words; this is akin to the problem faced orally when poor auditory analysis has taught the child such phrases as “lead a snot into temptation” and “Harold be Thy name” in the Lord’s prayer, or “lmnop” being one lumped cluster in the alphabet song.
  • Poor ability to remember individual sounds or sequences of sounds.
  • Difficulty blending individual sounds into words.
  • Difficulty listening to words and omitting one sound and substituting it for another (say cat; now take off the /c/ and put on an /f/); such abilities are essential for word analysis because that is what figuring out how to phonetically decode a word is all about; children usually develop this skill with initial consonants, and then medial vowels or consonants.
  • Difficulty remembering the sounds that individual letters and phonetically regular and irregular letter combinations represent.
  • Difficulty analyzing unknown words because of poor knowledge of phonetic rules and difficulty sequencing sounds.
  • Difficulty applying the phonetic rules from words that can be read to pseudowords that follow the same pattern but are not real words.
  • Vowel sounds are particularly troublesome.
  • Guessing at unfamiliar words rather than employing word-analysis skills.
  • Spelling remains below reading level because it is attempted by sight rather than by ear.
  • Correct spellings occur primarily on words that the child has encountered repeatedly and therefore can revisualize.
  • Bizarre spellings that seldom can be identified, even by the child, because they do not follow phonetic patterns.
  • Extraneous letters and omitted syllables in spelling.

Surface dyslexia

Synonyms for surface dyslexia include dyseidetic dyslexia, visual dyslexia or orthographic dyslexia.

This type of dyslexia refers to kids who struggle with reading because they can’t recognize words by sight. This is an important skill for a couple reasons. One is that some words have tricky spellings. Words like weight and debt can’t be sounded out — readers need to memorize them. The other reason has to do with reading fluency. To be able to read quickly and accurately, kids need to recognize many common words at a glance — without sounding them out.

Author Corinne Roth Smith lists the reading and spelling patterns of children with surface dyslexia:

  • Confusion with letters that differ in orientation (b-d, p-q).
  • Confusion with words that can be dynamically reversed (was-saw).
  • Very limited sight vocabulary; few words are instantly recognized from their whole configuration — they need to be sounded out laboriously, as though being seen for the first time.
  • Losing the place because one doesn’t instantly recognize what had already been read, as when switching one’s gaze from the right side of one line to the left side of the next line.
  • Omitting letters and words because they weren’t visually noted.
  • Masking the image of one letter, by moving the eye too rapidly to the subsequent letter, may result in omission of the first letter.
  • Difficulty learning irregular words that can’t be sounded out (for example, sight).
  • Difficulty with rapid retrieval of words due to visual retrieval weaknesses.
  • Visual stimuli in reading prove so confusing that it is easier for the child to learn to read by first spelling the words orally and then putting them in print.
  • Insertions, omissions, and substitutions, if the meaning of the passage is guiding reading.
  • Strengths in left hemisphere language-processing, analytical and sequential abilities, and detail analysis; can laboriously sound out phonetically regular words even up to grade level.
  • Difficulty recalling the shape of a letter when writing.
  • Spells phonetically but not bizarrely (laf-laugh; bisnis-business).
  • Can spell difficult phonetic words but not simple irregular words.

Double deficit 

You may also hear some people use the phrase double deficit. This refers to kids who struggle with phonological awareness and with something called rapid automatized naming (RAN). Rapid naming refers to the speed with which the names of symbols (letters, numbers, colors, or pictured objects) can be retrieved from long-term memory, and people with dyslexia typically score poorer on RAN assessments than normal readers. 

Some experts think slow naming speed reflects difficulties with phonological processing in reading. However, Landerl et al. (2018) examined 1,120 children acquiring one of five alphabetic orthographies with different degrees of orthographic complexity (English, French, German, Dutch, and Greek). While RAN was a universal predictor of reading in five alphabetic orthographies varying in consistency, no consistent pattern appeared for the phonological awareness–reading relationship. The researchers conclude that phonological awareness’s direct contribution to reading development might be less causal than is generally assumed.

Overall, processing speed seems to play a role in rapid naming.

Deep dyslexia

Deep dyslexia is used to describe a severe impairment and is accompanied by semantic errors (e.g. street is read as road), but also visual errors (e.g., badge is read as bandage), derivational errors (e.g., edition is read as editor) and difficulty reading functional words (e.g., as, the, so). Deep dyslexia is often described as an acquired reading disorder due to a brain injury. 

Dyslexia may co-occur with other learning disorders

Dyslexia may co-occur with other developmental disorders such as attention deficit hyperactivity disorder (ADHD), dyscalculia, dysgraphia or dyspraxia. 

Dyscalculia, which means inability to calculate, is the most widely used term for disabilities in arithmetic and mathematics.

Dysgraphia refers to a specific set of writing challenges that impacts writing skills like handwriting and spelling.

Dyspraxia refers to a developmental disorder that affects fine and gross motor skills, motor planning and coordination.

Key takeaways

References and sources:

De Jong, P. F., & van der Leij, A. (2003). Developmental changes in the manifestation of a phonological deficit in dyslexic children learning to read a regular orthography. Journal of Educational Psychology, 95(1), 22-40.

Elliott, J. G., & Grigorenko, E. L. (2014). The dyslexia debate. Cambridge: Cambridge University Press.

Landerl, K., Freudenthaler, H. H., Heene, M., de Jong, P. F., Desrochers, A., Manolitsis, G., … Georgiou, G. K. (2018). Phonological awareness and rapid automatized naming as longitudinal predictors of reading in five alphabetic orthographies with varying degrees of consistency. Scientific Studies of Reading, 1-15.

Mather, N., & Wendling, B. J. (2012). Essentials of dyslexia assessment and intervention. Hoboken, NJ: Wiley.

Opp, G. (1994). Historical roots of the field of learning disabilities: Some nineteenth-century German contributions. Journal of Learning Disabilities, 27, 10-19.

Smith, C. R. (1991). Learning disabilities: The interaction of learner, task, and setting. Boston: Allyn and Bacon.

Wydell, T. N., & Fern-Pollak, L. (2012). Preface. In T. N. Wydell, & L. Fern-Pollak (Eds.) Dyslexia – A comprehensive and international approach (pp. IX-XI). Rijeka, Croatia: InTech.

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