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Dyslexia
A primary reading disorder resulting from a written word processing abnormality in the brain, characterized by difficulties with accurate and/or fluent sight word recognition and by poor spelling and decoding abilities. These difficulties are unexpected in relation to the child's other cognitive skills.
Key features
- Neurobiological basis: Most individuals with dyslexia have a deficit in processing the sound structure of language (phonemic deficit), despite relatively intact overall language abilities. Functional MRI and PET studies demonstrate that dyslexia involves dysfunction in left-hemisphere posterior reading systems, with compensatory use of other brain regions.
- Genetic component: Approximately 40% of siblings, children, or parents of an affected individual will have dyslexia, with a strong genetic basis confirmed by genetic-linkage studies.
- Prevalence: Approximately 80% of people with learning disabilities have dyslexia, affecting an estimated 5–17.5% of the population. It occurs across all intelligence levels and throughout the world, and appears to affect boys more than girls.
- Common misconception: The definition of dyslexia does not include reversal of letters or words, or mirror reading or writing
- Not a vision problem: Dyslexia is a language-based disorder, not a visual one. It should be separated from secondary reading difficulties caused by visual or hearing disorders, intellectual disability, or inadequate instruction.
Joint Statement: Learning Disabilities, Dyslexia and Vision. AAO & AAP
Testing of Reading Skills
| Relevant Reading Area | Specific Assessments that may be used | Examples of Tasks |
|---|---|---|
| Letter-sound knowledge | Woodcock-Johnson IV Tests of Achievement (Word Attack, Spelling of Sounds) Kaufman Test of Educational Achievement, 3rd ed. (Letter Naming Facility, Letter Checklist) Process Assessment of the Learner, 2nd ed. (Letters) Wechsler Individual Achievement Test, 3rd ed. (Naming Letters, Letter-Sound Correspondence) | Identify individual letters Produce sounds for a small set of single letters Pronounce nonsense words of increasing complexity Write single letters and letter patterns presented orally Spell nonsense words |
| Word decoding | Woodcock-Johnson IV Tests of Achievement (Letter- Word Identification) Kaufman Test of Educational Achievement, 3rd ed. (Letter and Word Naming) Wechsler Individual Achievement Test, 3rd ed. (Word Reading) | Read a list of words in isolation (timed or untimed) Read a list of nonsense words in isolation (timed or untimed) |
| Reading fluency | Woodcock-Johnson IV Tests of Achievement (Oral Reading, Sentence Reading Fluency) Test of Word Reading Efficiency–2 (Sight Word Efficiency, Phonemic Decoding Efficiency) Kaufman Test of Educational Achievement, 3rd ed. (Word Recognition Fluency) Decoding Fluency Silent Reading Fluency Process Assessment of the Learner, 2nd ed. (RAN-Words, Morphological Decoding Fluency, Sentence Sense) Wechsler Individual Achievement Test, 3rd ed. (Oral Reading Fluency) Gray Oral Reading Tests, 5th ed. (Rate, Fluency) | Silently read a series of simple sentences and indicate if they are true or false (timed) Read a passage orally as quickly as possible Orally read a list of single words or nonsense words (timed) |
| Spelling (encoding) | Woodcock-Johnson IV Tests of Achievement (Spelling) Kaufman Test of Educational Achievement, 3rd ed. (Spelling) Process Assessment of the Learner, 2nd ed. (Word Choice) Wechsler Individual Achievement Test, 3rd ed. (Spelling) | Write single letters and spell words that are dictated Choose the correctly spelled word among a group of four words (three of which are misspelled) |
| Reading Comprehension | Woodcock-Johnson IV Tests of Achievement (Passage Comprehension, Reading Recall, Reading Vocabulary) Kaufman Test of Educational Achievement, 3rd ed. (Reading Comprehension) Process Assessment of the Learner, 2nd ed. (Does It Fit?, Sentence Sense Accuracy score; Sentence Structure) Wechsler Individual Achievement Test, 3rd ed. (Reading Comprehension) | Read a passage silently and answer questions based on the passage (passage may or may not be visible to the student when answering questions) Read a passage with a word or phrase missing, provide the missing word(s) Silently read three sentences One correct and two that contain a silly word that makes the sentence illogical (e.g., “The boy cames [sic] home late”) and circle the sentence that makes sense |
Testing of Cognitive Skills
| Relevant Cognitive Areas | Specific Assessments | Examples of Tasks |
|---|---|---|
| Phonological Awareness | Comprehensive Test of Phonological Processing–2 (Elision, Blending Words, Sound Matching, Phoneme Isolation) Woodcock-Johnson IV Tests of Oral Language (Segmentation, Sound Blending) Process Assessment of the Learner, 2nd ed. (Rhyming, Syllables, Phonemes, Rimes) | Repeat a nonword with the omission of a target sound (say stom without saying /t/); blend /m/ /a/ /t/ to form the word mat Identify specific phonemes in words (e.g., first, middle, last sound); break the word sun into its component sounds: /s/ /u/ /n/ |
| Phonological Memory | Comprehensive Test of Phonological Processing–2 (Memory for Digits, Nonword Repetition) Woodcock-Johnson IV Tests of Cognitive Abilities (Memory for Words) | Listen to a sequence of numerical digits and then recall the sequence correctly, with increasingly longer sequences being presented Listen to a nonsense word (e.g., keeftane) and then repeat it exactly |
| Orthographic Awareness | Woodcock-Johnson IV Tests of Cognitive Abilities (Letter–Pattern Matching) Test of Orthographic Competence; Kaufman Test of Educational Achievement, 3rd ed. (Orthographic Processing Composite) Process Assessment of the Learner, 2nd Ed. (Receptive Coding, Expressive Coding, Word Choice) | Choose the correct homophone (pair vs. pear) embedded in a sentence Recognize the correct spelling (bote vs. boat); unscramble words |
| Rapid Naming | Comprehensive Test of Phonological Processing–2 (Rapid Digit Naming, Rapid Letter Naming, Rapid Color Naming, Rapid Object Naming) Woodcock-Johnson IV Tests of Oral Language (Rapid Picture Naming) | Quickly name aloud a series of familiar items on a page (e.g., letters, numbers, colors or objects) |
| Processing Speed | Woodcock-Johnson IV Tests of Cognitive Abilities (Letter–Pattern Matching, Pair Cancellation) Wechsler Intelligence Scale for Children–V (Coding, Symbol Search) | Circle the identical letters or letter groups: bl va dl bl na; scan rows of pictures and circle each instance in which a certain picture is followed by a certain other picture (e.g., each cat followed by a tree). |
| Working Memory | Woodcock-Johnson IV Tests of Oral Language (Retrieval Fluency, Understanding Directions) Woodcock-Johnson IV Tests of Cognitive Ability (Object–Number Sequencing) | Name as many animals as you can in 1 minute Listen to the following sequence: cat, 7, 2, dog. What was the second number? |