Table of contents:
- Page 1: Dyslexia overview
- Page 2: Dyslexia’s history
- Page 3: Dyslexia symptoms
- Page 4: Dyslexia causes
- You’re here: Dyslexia types
- Page 6: Dyslexia case study
bear momee I canot reed plees help. Davib.
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 has dyslexia.
Dyslexia is a severe reading difficulty not caused by any profound sensory, neurological and intellectual disorders or socio-cultural factors. Depending on the definition and diagnostic criteria employed, dyslexia affects from 3% to 20% of the population, and up to 40% experience some type of reading difficulty. As with most disorders, dyslexia occurs on a continuum, varying from mild to severe, and there are many types and subtypes.
Primary, secondary, developmental, acquired
- Primary dyslexia refers to dyslexia when it is the result of a genetically inherited condition.
- Secondary dyslexia refers to reading difficulties that were caused by problems with brain development during the early stages of fetal development. Note that both primary and secondary dyslexia are considered developmental.
- Developmental dyslexia may be used to distinguish the problem in children and youth from similar problems experienced by persons after severe head injuries.
- When an adult or child has a brain injury from trauma or disease, they can sometimes develop difficulties with language processing, which may result in dyslexia. This type of dyslexia is referred to as acquired or trauma dyslexia.
Phonological, surface and deep
The terms phonological dyslexia and surface dyslexia are generally used to describe two main types of dyslexia. Synonyms for phonological dyslexia include dysphonetic dyslexia and auditory dyslexia, and synonyms for surface dyslexia include dyseidetic dyslexia, visual dyslexia and orthographic dyslexia. Deep dyslexia is sometimes used to describe a severe impairment.
– Phonological 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, he can hear the word just fine and repeat it back to you. But he’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.
Smith (1991) 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
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 of 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.
Smith (1991) 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 the 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.
– 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.
More types, researchers say
In their article, “Types of developmental dyslexia,” Friedmann and Coltheart (2018) discuss phonological dyslexia and deep dyslexia, and distinguish between surface and visual dyslexia, which is mostly used synonymously. They also list five other types of dyslexia:
– Letter position dyslexia
Individuals who have a deficit in this function can still identify the letters correctly, but fail to encode the order of the letters within the word. This dyslexia is called letter position dyslexia (LPD), and its cardinal symptom is migrations of letters within words. Thus, words like cloud can be read as could, fried as fired, and dairy as diary. Another related type of error that individuals with LPD make is the omission of doubled letters: for example, they may read drivers as divers, and baby as bay.
– Attentional dyslexia
In attentional dyslexia, letters migrate between neighboring words, but are correctly identified and keep their original relative position within the word. For example, the word pair cane love can be read as lane love or even lane cove.
– Letter identity dyslexia
Letter identity dyslexia is a deficit in the orthographic-visual analysis, in the function responsible for creating abstract letter identities. It is not a visual deficit, as readers with this dyslexia can still match similar non-orthographic forms, visually match two instances of the same letter in different sizes, and copy letters correctly. However, readers with letter identity dyslexia cannot access the abstract identity of letters from their visual form, so they cannot name a letter, identify a written letter according to its name or sound, or match letters in different cases (e.g., A and a).
– Neglect dyslexia
A condition in which a person is unaware of half of the visual field as a result of neurological damage. Either the initial parts of words are misread (left neglect) or the terminal parts of words are misread (right neglect), and the errors are not simple deletions but typically guesses of real though incorrect words with approximately the right number of letters.
– Vowel letter dyslexia
Individuals with vowel dyslexia omit, substitute, transpose, and add vowel letters. Thus, the word bit can be read as bat, but or even boat.
According to some scholars, however, research does not support the use of dyslexia subtypes to guide assessment and intervention (Peterson et al., 2014).
Other important concepts
– 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.
– 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 also goes by the name “clumsy child syndrome.” If your child has dyspraxia, he has trouble planning and coordinating his body movements and struggles with fine motor tasks like writing, buttoning his clothes, and tying his shoelaces. He may have difficulty coordinating his facial muscles to produce sounds, so his speech is garbled. His large motor coordination may be weak too, so he’s conspicuously clumsy and weak at sports.
Video: Overcoming dyslexia
Meet Hilary, Rief’s mom. This video is about Hilary and her 9-year-old son who struggled with dyseidetic dyslexia. Hilary reports measurable improvements in standardized reading scores and confidence.
NEXT: Page 6: Dyslexia case study
Authored by Susan du Plessis (B.A. Hons Psychology; B.D.) who has 30+ years’ experience in the LD field.
Medically reviewed by Dr. Zelda Strydom (MBChB) on May 21, 2021.
Next review due: May 21, 2023.
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.
Friedmann, N., & Coltheart, M. (2018). Types of developmental dyslexia. In A. Bar-On, & D. Ravid (Eds.), Handbook of communication disorders: Theoretical, empirical, and applied linguistics perspectives. Berlin, Boston: De Gruyter Mouton.
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.
Peterson, R. L., Pennington, B. F., Olson, R. K., & Wadsworth, S. (2014). Longitudinal stability of phonological and surface subtypes of developmental dyslexia. Scientific Studies of Reading, 18, 347-362.
Smith, C. R. (1991). Learning disabilities: The interaction of learner, task, and setting. Boston: Allyn and Bacon.
Wood, T. (2006). Overcoming dyslexia for dummies. Hoboken, NJ: Wiley Publishing, Inc.
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.