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Dyslexia Clinical Reference
Phonological Processing · Orthographic Mapping · Identification · Differential Considerations
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SLD — Basic Reading / Reading Fluency / Reading Comprehension

Dyslexia Reference

Dyslexia is a specific learning disability rooted in deficits of phonological processing that impair accurate and/or fluent word recognition, decoding, and spelling. It is not a visual processing disorder or a matter of "seeing letters backwards" — it is a language-based learning disability that reflects a weakness in the phonological component of language, often unexpected relative to the student's cognitive ability and access to adequate instruction. Identification requires evaluating phonological processing alongside word-level reading and ruling out inadequate instruction as the primary cause.

Texas Dyslexia Handbook — Dyslexia Identification Questions
Figure 4.1 — Three Required Questions

All three questions must be addressed in an evaluation where dyslexia is suspected (Texas Dyslexia Handbook, 2024, p. 43).

1
Characteristics & consequences present?
• Difficulty with accurate and/or fluent word recognition
• Poor decoding and/or poor spelling
• Secondary consequences may include difficulties in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge
2
Underlying mechanism present?
Do these difficulties typically result from a deficit in the phonological component of language — including phonological awareness, phonological memory, and/or rapid automatized naming?
3
Unexpected for age and ability?
Are these difficulties unexpected for the student's age in relation to the student's other abilities and the provision of effective classroom instruction?

Source: Texas Dyslexia Handbook pp. 43–44 (2024); IDA Definition (2002/2003)

⚠️ What Dyslexia Is — and Is Not

Common misconceptions complicate identification. The evaluator should be prepared to address these in the FIE and in ARD conversations.

Is a phonological processing deficit affecting word-level reading, decoding, and spelling
Is neurobiological in origin — present from birth, with a hereditary component
Can coexist with average or above-average intelligence; IQ is not a gate
Is not a visual disorder — students do not "see letters backwards"
Is not caused by lack of effort, poor teaching alone, or low motivation
Is not simply "slow reading" — fluency deficits are a consequence of word-recognition failure, not a separate disorder
May improve with intensive structured literacy intervention — but the underlying phonological profile remains; scores ≥85 at reeval indicate intervention success, not resolution

Source: IDA Definition (2002/2003); Texas Dyslexia Handbook (2024)

The Three Core Phonological Processing Deficits
🔊 Phonological Awareness (PA)

What it is: The ability to detect, manipulate, and reflect on the sound structure of language — independent of meaning. The bedrock skill for decoding and spelling.

Key skills (developmental order):

  • Rhyme awareness and production
  • Syllable segmentation and blending
  • Onset-rime manipulation
  • Phoneme isolation, segmentation, blending
  • Phoneme deletion, substitution, reversal

Assessment tools:

CTOPP-2 PA Composite CTOPP-2 Phonological Awareness WJ-V Sound Awareness KTEA-3 PA TAPS-4 Phonological Processing Index
FIE framing: PA deficits explain why the student cannot reliably map phonemes to graphemes during decoding or reverse the process during spelling — even with strong vocabulary and language comprehension.
🧠 Phonological Memory (PM)

What it is: The ability to temporarily hold phonological information in working memory — essential for blending phonemes while decoding multisyllabic words and for retaining newly learned letter-sound associations.

Observable indicators:

  • Difficulty repeating nonsense words
  • Loses the beginning of a word while decoding the end
  • Difficulty retaining new vocabulary or names
  • Low digit span performance

Assessment tools:

CTOPP-2 Memory for Digits CTOPP-2 Nonword Repetition WISC-V Digit Span WJ-V Numbers Reversed TAPS-4 Auditory Memory Index TAPS-3:SBE (Spanish/bilingual)
Note: PM deficits often explain why these students plateau in structured literacy — they can learn a rule in session but cannot hold the phonological sequence long enough to apply it in running text.
Rapid Automatized Naming (RAN)

What it is: The speed at which familiar symbols — letters, digits, colors, objects — can be retrieved from long-term memory and named in sequence. RAN is distinct from PA and strongly predicts reading fluency.

Observable indicators:

  • Slow, labored oral reading despite knowing words individually
  • Word retrieval difficulties in conversation
  • Slow letter and digit naming on timed tasks
  • Reading that does not become automatic despite repeated practice

Assessment tools:

CTOPP-2 RAN Composite CTOPP-2 RAN Letters/Digits CTOPP-2 RAN Colors/Objects
Double-Deficit Hypothesis: Students with deficits in both PA and RAN (the double deficit profile) show the most severe reading impairment and the slowest response to intervention (Wolf & Bowers, 1999).
Orthographic Mapping — Why Word Recognition Doesn't Become Automatic
🗺️ The Orthographic Mapping Framework

Orthographic mapping (Ehri, 2014) is the process by which a reader forms a permanent, instant-access memory for a word's spelling, pronunciation, and meaning. It is how sight words are built — not through rote memorization, but through the systematic connection of phonemes to graphemes.

For orthographic mapping to occur, the reader must:

  • Segment the spoken word into phonemes (phonological awareness)
  • Know the grapheme-phoneme correspondences (alphabetic knowledge)
  • Bond the phonological and orthographic representations in long-term memory

Students with dyslexia have weak phonological representations — the "pegs" onto which orthographic knowledge is hung are unstable. This is why:

  • Sight words must be re-taught repeatedly without retention
  • Decoding of novel words is slow and error-prone
  • Reading fluency lags far behind listening comprehension
  • Spelling is inconsistent even for words previously mastered
FIE implication: When a student has adequate language comprehension and cognitive ability but cannot form automatic word-level representations, the orthographic mapping framework directly supports the "unexpected" prong of dyslexia identification. Address this explicitly in the FIE.

Source: Ehri (2014); Kilpatrick (2015); Texas Dyslexia Handbook (2024)

📖 Simple View of Reading

The Simple View of Reading (Gough & Tunmer, 1986) defines reading comprehension as the product of two component skills:

Reading Comprehension = Decoding × Language Comprehension

This framework is essential for differential eligibility reasoning:

Profile Decoding Lang. Comp. Reading Comp.
Dyslexia Weak Adequate–Strong Impaired (word-level bottleneck)
DLD/SLI Adequate Weak Impaired (language bottleneck)
Mixed (Dyslexia + DLD) Weak Weak Severely impaired
Hyperlexia Strong Weak Impaired (comprehension bottleneck)
Practical move: Compare oral language composites (listening comprehension, vocabulary, oral expression) to decoding/word recognition scores. A strong oral language profile alongside weak word reading is the canonical dyslexia presentation.

Source: Gough & Tunmer (1986); Hoover & Gough (1990); Texas Dyslexia Handbook (2024)

Assessment Data Sources
📊 Norm-Referenced

Phonological Processing:

CTOPP-2 PA Composite CTOPP-2 RAN Composite CTOPP-2 PM Composite WJ-V Phonological Processing TAPS-4 TAPS-3:SBE (Spanish/bilingual)

Word-Level Reading:

WIAT-IV Word Reading WIAT-IV Pseudoword Decoding KTEA-3 Letter & Word Recognition KTEA-3 Nonsense Word Decoding WJ-V Letter-Word ID / Word Attack

Reading Fluency:

WIAT-IV Oral Reading Fluency KTEA-3 Reading Fluency WJ-V Oral Reading / Reading Fluency GORT-5 TOWRE-2

Spelling:

WIAT-IV Spelling KTEA-3 Spelling WJ-V Spelling
📋 Informal / Clinical

Oral Reading Sample: Have the student read a grade-level passage aloud. Record error types: substitutions, omissions, insertions, self-corrections. Phonetically implausible errors (e.g., "horse" for "house") indicate phonological decoding failure. Phonetically plausible errors (e.g., "hous" for "house") suggest PA awareness but incomplete orthographic mapping.

Decoding Probe: Present 10–15 pseudowords of increasing length (CVC → CCVCC → multisyllabic). Slow, effortful, or phonologically inaccurate decoding is a direct measure of phoneme-grapheme mapping failure — not a reading comprehension issue.

Spelling Error Analysis: Collect unedited writing samples. Classify errors:
Phonologically implausible (e.g., "tge" for "the") → PA deficit
Phonologically plausible (e.g., "duz" for "does") → orthographic mapping weakness, phonology intact
Omission of phonemes (e.g., "wnt" for "went") → phoneme segmentation deficit

Intervention Response History: Document Tier 2/3 interventions, fidelity, duration, and progress monitoring data. Resistance to evidence-based structured literacy intervention supports the "unexpected" and "inadequate instruction excluded" prongs.

🔍 Oral Language vs. Reading Comparison

The most clinically powerful indicator of dyslexia — versus a broader language-based disability — is the gap between oral language ability and written word recognition. Collect and compare:

  • Oral vocabulary / listening comprehension — typically adequate to strong in dyslexia
  • Verbal reasoning / oral expression — typically intact
  • Word reading / decoding — significantly below oral language level
  • Reading comprehension — impaired through word-level bottleneck, not language itself
Key contrast: Ask the student to listen to a passage and answer comprehension questions. If listening comprehension is substantially stronger than reading comprehension, the deficit is word-level — not language — which directly supports dyslexia rather than DLD as the primary eligibility area.

Framework: Gough & Tunmer (1986); WJ-V OL Cluster; WIAT-IV Listening Comprehension

Reevaluation — Persistence Rule & Scores ≥85
🔁 Dyslexia Does Not Resolve — It Responds to Intervention

At reevaluation, scores at or above standard score 85 (16th percentile) are not evidence that dyslexia has resolved. They are evidence that structured literacy intervention has been effective. The underlying phonological processing profile and the student's need for ongoing accommodations remain.

Apply the persistence rule when:

  • Prior FIE documented dyslexia eligibility and
  • Reeval scores are ≥85 in word reading, decoding, or reading fluency

Document in the FIE:

  • The student received intensive structured literacy intervention consistent with the original eligibility area
  • Score improvement is attributed to intervention success — not to the absence of a disability
  • The student continues to require accommodations (extended time, audiobooks, text-to-speech) to access grade-level curriculum without the disability impacting educational performance
  • Discontinuing eligibility would remove supports that are sustaining current functioning
HB 3928 (88th Leg., 2023): Clarified that a student identified with dyslexia under SLD may continue to be served under SLD even when reading scores normalize — the disability does not disappear because intervention compensated for it. Removing eligibility solely on the basis of improved scores without considering the role of supports is not defensible under IDEA or Texas law.

Source: Texas Dyslexia Handbook (2024); HB 3928 FAQ (TEA, 2023); IDEA 2004 §614(c)

ADHD & Dyslexia — High Overlap, Distinct Mechanisms
Co-occurrence and Differentiation

Estimates suggest that 25–40% of students with dyslexia also meet criteria for ADHD, and vice versa. Co-occurrence is common enough that evaluators should routinely consider both when either is suspected. Despite the overlap, the mechanisms are distinct:

Dimension Dyslexia OHI — ADHD (reading impact)
Primary mechanism Phonological processing deficit — word recognition and decoding specific Attention, executive self-regulation — access and sustained effort
Reading across conditions Consistently weak regardless of interest level, reading support, or environmental structure Variable — improves with high-interest text, brief sessions, movement breaks, and structure
Decoding accuracy Poor even on brief, single-word tasks in a quiet, distraction-free environment Decoding accuracy often adequate; breakdowns occur under sustained load
Fluency pattern Slow due to word-level processing failure — phonological bottleneck Slow due to inconsistent attention deployment — not word-level failure
Phonological processing Deficits evident on direct PA, PM, and RAN measures Phonological processing typically intact; reading fluency may be inconsistent
Dual eligibility appropriate? Yes — when both conditions independently contribute to educational need. Document each disability's independent contribution. Both SLD (dyslexia) + OHI-ADHD may be appropriate when phonological deficits and attention/EF deficits are each separately limiting educational performance.

Sources: Willcutt & Pennington (2000); Shaywitz, S. E., & Shaywitz, B. A. (2020). Overcoming Dyslexia (2nd ed.). Knopf; TEA SLD Guidance (2025)

Dyslexia vs. DLD — Differential Identification
⚖️ Dyslexia vs. Developmental Language Disorder (DLD)

Dyslexia and DLD (also documented as SLI or language-based learning disability) are the most commonly confused profiles in reading evaluations. Both can produce low reading comprehension — but through entirely different mechanisms, with different eligibility implications and different instructional needs.

Dimension Dyslexia DLD / SLI Mixed (Dyslexia + DLD)
SVR bottleneck Decoding weak; language comprehension adequate–strong Decoding adequate; language comprehension weak Both decoding and language comprehension weak
Word reading / decoding Significantly below average; pseudoword decoding especially poor Often average or near-average; may decode words without understanding them Below average on both word reading and comprehension
Reading comprehension Impaired through word-level bottleneck — improves substantially when text is read aloud Impaired even when text is read aloud — the comprehension deficit is in the language system, not the decoding system Impaired in both conditions
Listening comprehension Intact — strong relative strength; student understands what is heard Weak — vocabulary, syntax, inferencing, and/or narrative comprehension all affected Weak, though may be stronger than reading comprehension
Oral vocabulary / verbal reasoning Typically age-appropriate; may be a relative strength Below average; limited vocabulary depth and breadth; reduced verbal reasoning Below average in both areas
Phonological processing PA, PM, and/or RAN deficits evident on direct testing Phonological processing may be intact or mildly low; not the primary profile PA/PM deficits present alongside language deficits
Spelling pattern Phonologically implausible or phonologically plausible errors — phonology-based breakdown May spell phonetically but use words incorrectly; semantic and morphological errors Mixed error patterns
Key clinical move Read the passage aloud — if reading comprehension improves significantly, the bottleneck is decoding, not language Read the passage aloud — if comprehension remains poor even when text is read aloud, the bottleneck is language Both conditions apply independently
Eligibility pathway SLD — Basic Reading Skills / Reading Fluency (dyslexia) Speech-Language Impairment (SLI) — collaborative determination with SLP; may also qualify as SLD-Reading Comprehension Dual eligibility: SLD (dyslexia) + SLI — each documented separately
The read-aloud probe is the single most useful clinical move: Administer a reading comprehension measure (or passage questions) twice — once having the student read independently, once reading the passage aloud to the student. A large comprehension gain when text is read aloud points to dyslexia. Little or no gain points to DLD. This finding belongs in the FIE and should be explicitly named for the ARD committee.

Framework: Gough & Tunmer (1986); Catts et al. (2006); Tunmer & Hoover (2019); Stanley, TEDA 2026

Reevaluation — Sample FIE Language
📝 When Scores Have Normalized (≥85)

Use when reeval reading scores are at or above SS 85 but prior eligibility was dyslexia and the student received structured literacy intervention. Adapt as needed.

1
Frame the score improvement as intervention outcome:
"[Student]'s current word reading and decoding scores fall within the average range (SS [X], [X]th percentile). This represents meaningful growth from the [prior year] evaluation, during which scores were in the [below average/low] range. [Student] has received [intervention name] — an evidence-based structured literacy program — with documented fidelity for [duration]. Current scores reflect the educational impact of that intervention, not the absence of a learning disability."
2
Anchor continued eligibility in ongoing need:
"[Student] continues to demonstrate characteristics consistent with dyslexia, including [e.g., slower reading rate on timed tasks / continued phonological processing weaknesses / spelling errors consistent with orthographic mapping difficulty]. [Student]'s current academic functioning is being sustained by the accommodations and supports currently in place. Removing eligibility at this time would discontinue access to supports that are directly enabling [his/her/their] present level of performance."
3
State the eligibility conclusion directly:
"The evaluation team concludes that [Student] continues to meet eligibility criteria for Specific Learning Disability in the area of Basic Reading Skills consistent with characteristics of dyslexia. Pursuant to HB 3928 (88th Leg., 2023) and the Texas Dyslexia Handbook (2024), score normalization in the context of intensive structured literacy intervention does not constitute resolution of the disability."
📝 When Scores Remain Below Average

Use when reeval scores remain in the below-average or low range and dyslexia pattern is persistent. Adapt as needed.

1
Document the persistent pattern:
"[Student]'s reading profile at reevaluation remains consistent with the pattern identified in [prior year]. Word reading (SS [X]), pseudoword decoding (SS [X]), and reading fluency (SS [X]) continue to fall in the [below average/low] range. Phonological processing measures [describe: e.g., CTOPP-2 PA Composite SS [X], RAN Composite SS [X]] remain below age expectations, indicating that the underlying phonological processing deficit has not resolved."
2
Address intervention history:
"[Student] has received [intervention] at [Tier 2/3] for [duration]. Progress monitoring data indicate [describe: e.g., growth at a rate below grade-level peers / inconsistent response / growth in some areas but not others]. This pattern of limited response to evidence-based structured literacy instruction is consistent with a significant phonological processing deficit and further supports the presence of a specific learning disability in reading."
3
Connect to educational impact:
"[Student]'s reading difficulties continue to adversely affect educational performance across settings, including [e.g., access to grade-level text in science and social studies / timed reading and writing tasks / independent completion of reading assignments]. [Student] requires continued specially designed instruction and accommodations to access the general education curriculum."
💬 ARD-Friendly Framing — Explaining Persistent Eligibility to Parents

Parents and general education staff sometimes question continued eligibility when scores have improved. These talking points can support the ARD conversation:

  • "Think of it like glasses." A student who needs glasses to see 20/20 does not have their vision disorder resolved — they have it corrected. Removing the glasses removes the correction. Structured literacy, extended time, and text-to-speech are [Student]'s "glasses."
  • "The intervention is working — that's the point." Score improvement is the goal of the intervention. It does not mean the disability is gone; it means the supports are doing their job.
  • "Texas law specifically addresses this." HB 3928 (2023) clarified that students identified with dyslexia can continue to receive services under SLD even when scores normalize, as long as the need for supports continues.
  • "What would happen without the supports?" If the student would struggle to access grade-level work without accommodations, the adverse educational effect is still present — it is being managed, not eliminated.
Documentation tip: Include a statement in the FIE that explicitly names the accommodations currently in place and notes that those accommodations are contributing to the student's present level of performance. This creates the evidentiary link between continued need and continued eligibility.
Texas Dyslexia Identification — By the Numbers
📊 Statewide Identification Trends (2016–2023)

A peer-reviewed analysis of Texas PEIMS data across 839 school districts (Simmons, Shin & Hart, 2024, Texas Education Review) documents the impact of federal corrective action and state legislation on dyslexia identification rates:

  • 2016–17 baseline: 4.10% of total Texas student enrollment identified with dyslexia statewide.
  • 2022–23: 7.03% — a 3-percentage-point increase representing approximately 142,130 additional students across Texas.
  • Primary driver: The 2018 OSEP Corrective Action to TEA (finding that TEA failed to ensure all students with disabilities were identified and evaluated) is identified as the single strongest catalyst for the identification increase.
  • Most conservative national estimate of true dyslexia prevalence is 5% (Odegard et al., 2020) — Texas is now approaching and in many districts exceeding this threshold.
For your practice: Rising identification rates are not evidence of over-identification — they are evidence of prior under-identification being corrected. The OSEP finding confirmed that Texas districts had systematically failed to find students who qualified. This is the context for your current caseload volume.
🗺️ Identification Rates by District Type

The Simmons et al. (2024) analysis broke down identification trends by NCES district locale — revealing important patterns relevant to suburban Texas diagnosticians:

  • Rural districts had the highest baseline identification in 2016–17 (4.78%) but the slowest rate of increase (+1.5% over 7 years). Rural districts had historically served more students with disabilities before the 8.5% enrollment cap was enacted (2004).
  • Suburban districts showed the greatest rate of increase — 2.77 percentage points over the study period — more than any other locale type. Suburban districts like those in the Williamson County area were likely among the lowest identifiers pre-corrective action and are "catching up."
  • City districts increased from 2.80% to 5.29%; town districts from 3.88% to 6.62%; rural from 4.78% to 7.95%.
  • Urban (city + suburban combined) increased 3% vs. rural (town + rural combined) increase of 2% — suburban growth is driving the statewide trend.
Practical implication: If your campus or district has seen a surge in dyslexia referrals, that is consistent with the statewide pattern for suburban districts. It reflects policy correction, not evaluation inflation.

Source: Simmons, M., Shin, M., & Hart, S. (2024). Dyslexia identification: Texas legislative trends in prevalence rate of students by school district locale. Texas Education Review, 12(2), 6–24.

🤠

Texas Policy — Dyslexia & SLD-Basic Reading / Reading Fluency

Dyslexia is identified within the SLD category under Texas TAC §89.1040 and TEC §38.003. Students are reported under the SLD eligibility category, with dyslexia named as the specific pattern of need — it does not require co-occurring deficits in other SLD areas. The Texas Dyslexia Handbook (2024) is the primary policy document governing identification; all public schools are required to follow it.

HB 3928 (88th Leg., 2023) clarified that dyslexia may be listed as the specific learning disability identified — it does not need to be subsumed under a broader SLD label. This is consistent with the OSERS Dear Colleague Letter (October 23, 2015), which clarified that nothing in IDEA prohibits the use of the terms dyslexia, dysgraphia, and dyscalculia in evaluation reports, eligibility determinations, and IEP documents.

The Texas Dyslexia Handbook (2024) requires that evaluations include assessment of the phonological component of language (PA, PM, RAN) and word-level reading (word recognition, decoding, spelling). Evaluation teams must also consider data from K–1 universal screening, classroom-based observations, intervention response history, and parent/teacher input.

Universal Screening: Under TEC §28.006, all students in kindergarten and first grade must be screened for reading difficulties, including characteristics of dyslexia, using a TEA-approved screening instrument. Screening data must be included in the FIE for students in these grades when dyslexia is the area of concern.

Bilingual/EB considerations: Dyslexia can be identified in English learners when the phonological processing deficit is present in the student's dominant language and cannot be attributed solely to normal second-language acquisition. Cross-linguistic phonological assessment using the Batería IV COG or Spanish CTOPP equivalent is recommended when Spanish is the dominant language.

Sources: Texas Dyslexia Handbook (2024); TEC §38.003; TEC §28.006; TAC §89.1040; HB 3928 FAQ (TEA, 2023); OSERS Dear Colleague Letter (October 23, 2015); TEA Guidance for the Comprehensive Evaluation of SLD (January 2025)

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Reference Note: Subtest descriptions, score interpretations, and clinical guidance on this page are summarized for professional reference by educational diagnosticians. Practitioners should consult official test manuals and cited source publications for standardized procedures and complete frameworks. Eligibility determinations must be made by a qualified multidisciplinary ARD team. Barber Sped Hub is an independent diagnostic reference and is not affiliated with or endorsed by any test publisher, researcher, or professional organization.