Design for Dyslexia

Instructional Design with Dyslexia in Mind

Types of Dyslexia

Aren’t All Dyslexics Alike?

No, people with dyslexia are as unique as every other person. However, understanding their dyslexia leads to empowerment. For older students and adults, knowing their dyslexia type enables them to develop coping skills and target solutions to specific challenges. It also guides teachers, tutors, and parents in focusing remediation efforts.

There is no official list of dyslexia types.  Although there are as many as 7 types of dyslexia described in various sources, the most common are:

  • Phonological dyslexia
  • Surface dyslexia
  • Rapid Automatic Naming Dyslexia
  • Double Deficit Dyslexia
  • Stealth Dyslexia

Let’s look at each in more detail.

Phonological, Dysphonetic, or Auditory Dyslexia

Phonological dyslexia is related to the ‘phonemes’ or individual units of sound in spoken language. These individuals have difficulty manipulating the sounds in words, including breaking down words or taking a string of sounds and blending into a single word.  ‘Dys’ is a prefix meaning difficulty with, therefore phonological dyslexia is also often called dysphonetic dyslexia or auditory dyslexia.  Dr. Corrine Roth Smith, expert in learning disabilities research and Emeritus Professor at Syracuse University, lists ways that phonological weaknesses are displayed.

  • Auditory dyslexics have difficulty mentally processing rapid auditory input, which can translate to missing letters when spelling.
  • They exhibit difficulty manipulating the sounds in syllables or words and playing auditory processing games such as elision (say “cat”, now say “cat” without the /k/, correct answer would be “at”.) Separating the individual sounds in words, like /k/ /a/ /t/ for “cat” or blending the individual sounds into a word are challenging.
  • Distinguishing between short vowel sounds for reading and spelling is difficult.
  • Difficulty rapidly retrieving and retaining appropriate sounds when presented with letters, sometimes omitting beginning sounds on words. This challenge would be highlighted in the third type of dyslexia listed below, Rapid Automatic Naming Dyslexia.
  • Failure to recognize and manipulate words by changing the initial consonant sounds (fat, cat, hat), then later the middle vowel sounds (cap, cup), and the final consonants (gum, gut, gulp) would indicate later difficulty with decoding.
  • Often auditory dyslexics guess at unfamiliar words rather than using phonological word-attack skills such as syllable division patterns and the effect of syllable type on vowel sounds. While these dyslexic readers have weak or non-existent word analysis tools, visual dyslexics, discussed below, utilize word attack tools such as syllable types to sound out and blend multi-syllabic words.
  • Like many dyslexics who use context clues when reading, substitutions may preserve meaning, but not be phonetically similar words, like saying “daughter” instead of “girl” when reading about a family.
  • Longer, unknown words are difficult to analyze and sound out due to phonological deficits, although irregular words may not be an issue as they are for the visual dyslexics discussed below.
  • When spelling is incorrect, even the writer may have difficulty deciphering because the word does not follow regular phonetic patterns.

Surface Dyslexia

Surface dyslexia refers to challenges with words that are pronounced differently than they are spelled, often called irregular words or “red words” indicating caution. Examples would be ‘was’ or ‘yacht’.  Surface dyslexia is also called dyseidetic dyslexia, referring to difficulty (‘dys’) with eidetic memory, or photographic memory.  

Eidetic memory allows most readers to recognize the shape and pattern of a word after a few exposures without using a mnemonic, cuing device. Although surface dyslexia is also referred to as visual dyslexia, it is not an issue with the eyes or ability to see.  Instead, it is an issue with inability to form a picture of irregular words, not the ability of the eyes to see the letters and words.

Surface/Visual/Dyseidetic Dyslexics

Surface/Visual/dyseidetic dyslexics also find a number of other tasks troublesome which rely upon visual processing. Dr. Smith noted other areas in which visual processing impedes fluency and comprehension.

  • Do not readily recognize sight words and therefore attempt to decode these non-phonetic, irregular spellings without immediately recognizing the so-called ‘red words’. Non-dyslexic readers form a picture, or gestalt, after a few key encounters with a word, which includes the shape and other visual characteristics.
  • May have the most difficulty with small non-phonetic words, such as ‘push’, ‘walk’, ‘where’, or ‘what’. Even though they have likely seen the word before, they fail to make a visual, photographic memory and instead attempt to sound out the word on each encounter.
  • Frequently confuse the letters b, d, p, and q, and words like ‘saw’ and ‘was’ impeding accuracy.
  • May also leave out letters when both reading and spelling, visually brushing right over letters and omitting their sounds.
  • Frequently lose their place when tracking from the end of one line to the beginning of the next.

Like many dyslexics who use context clues when reading, visual dyslexics may substitute words with similar meanings and some phonetic similarities, such as cat for kitten.

In contrast to phonological dyslexics, visual dyslexics are often able to attack long, multi-syllabic words using phonics rules and patterns.

Unlike phonological dyslexics’ spelling, visual dyslexics spell phonetically, such as ‘lite’ for ‘light’.

Rapid Automatic Naming Dyslexia

Rapid automatic naming, or recognition of letters, is a requirement for reading quickly and fluently with automaticity. The more time the brain needs to determine not only which letters it sees, but also to then attach sounds to those letters or letter combinations, the slower the reading process.  Just as knowing math facts affects the speed of mathematics computation, rapid number naming difficulty slows the entire process.  Rapid Automatic Naming for both letters and numbers is a subtest on the Comprehensive Test of Phonological Processing (CTOPP), which gives insight into processing speed.

Double Deficit Dyslexia

Double deficit dyslexia means simply that an individual experiences more than one type of dyslexia. For those with phonological dyslexia, often rapid automatic naming dyslexia is also a problem.  Similarly, many students who have phonological/dysphonetic dyslexia also have difficulty with irregular words, and therefore also have surface/dyseidetic/ visual dyslexia.

While other types of dyslexia appear online, these four are considered the most common.  Some authors mention right-to-left dyslexia, but other researchers feel this distinction does not merit its own category.

Stealth Dyslexia

Stealth dyslexia is a term coined by Drs. Brock and Fernette Eide, authors of The Dyslexic Advantage. Dr. Fumiko Hoeft, one of the world’s foremost dyslexia researchers at the University of California San Francisco, has published numerous articles and videos on stealth dyslexia. People with stealth dyslexia are frequently overlooked in dyslexia diagnosis, because their reading comprehension is above average. However, they struggle with phonics and decoding, often underperforming in the classroom and rarely receiving the help they need.

Comparison of Challenges for Auditory and Visual Dyslexia

Challenge

Phonological (Dysphonological/Auditory) Dyslexia

Surface (Dyseidetic/Visual) Dyslexia

Irregular SpellingsForm a mental image of irregular words, enabling recognition of the word after a few exposures.  Picture the word as a whole and do not use phonological attack skills.Fail to utilize eidetic (photographic) memory to form a ‘gestalt’ or image of a word.  Attempt to sound out irregular words using phonological attack skills which impedes fluency.
New, single or multi-syllabic wordsUnable to efficiently use phonological letter-sound correspondence, order of phonemes, and syllable division patterns to sound out and blend new words.Apply phonological word-attack knowledge, syllable division patterns, and phonological patterns to attack even longer new vocabulary.
Non-word reading and spellingUnable to apply phonological rules to reading on nonsense words.Able to use word-attack skills to sound out non-sense words, provided that all letters are visually captured and not glossed over in print
Sight vocabularyLimited sight vocabulary due to lack of phonological knowledge to acquire larger vocabulary.Limited sight vocabulary due to non-formation of eidetic memory or gestalt (image of word)
Letter omissionsMay omit letters when spelling due to poor auditory memory for sounds at the beginning of a word. Sometimes omits short consonant sounds (/p/, /b/, /t/) due to glossing over short auditory sounds.May omit letters or words when reading due to visually glossing over letters in print. Or may omit letters or sounds when reading if using context clues.
Word gamesDifficulty manipulating sounds in words for rhyming practice, elision (dropping sounds from a word), separating the individual phonemes in words, or blending phonemes into wordsLess difficulty with word games using auditory input.
Phonological MemoryDifficulty recalling the sounds that letters or letter combinations represent for reading and spelling.Uses knowledge of letter-sound correspondence to sound out and blend single and multi-syllabic words.
b/d/p/q confusionConfusion of letter sounds rather than letter graphemes or representations.Confuses letters that look similar or can be rotated.  Confusion of words that can be reversed (‘was’ and ‘saw’).
Rate of RetrievalUnable to rapidly retrieve letter-sound or sound-letter correspondence which may lead to forgetting the beginning of the word.May also have slow rate of letter retrieval due to visual retrieval processing.  Irregular sight words must be sounded out slowly (often incorrectly) each time encountered.
Unfamiliar wordsGuessing, potentially using context clues, but not phonetic clues.  May or may not preserve meaning depending upon the situation.May also substitute based upon context, but more likely to be phonetic substitutions that preserve meaning.
Spelling levelBelow reading level, often bizarre, due to reliance on sight, not phonetic clues.  Extra or omitted sounds and syllables.Likely to use phonetic clues, but not sight (or gestalt) of words, although spelling may still be incorrect. (lite for light)
Spelling patternsGenerally, most often correct on high frequency known words

Generally, most often correct for regular, phonetic words, not irregular sight words.

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