E0012025definitionconfidence high
International Dyslexia Association 2025 Definition of Dyslexia
Evidence type: scientific consensus definition
Dyslexia involves persistent difficulty with word reading and or spelling accuracy, speed, or both. Presentation varies with orthography and reflects interacting genetic, neurobiological and environmental influences.
Design implication: Do not model dyslexia as a single visual defect. Build a multidimensional and orthography aware system.
Scope: dyslexia specific. Causal status: framework. Audit date: 2026-10-05.
Open primary or indexed sourceE0022026fontconfidence high
Does font improve reading in dyslexic children?
Evidence type: meta analysis
Specialist dyslexia fonts do not show a reliable overall advantage over standard fonts for reading speed or accuracy.
Design implication: Do not make a fixed specialist font the core hypothesis. Optimize measurable typographic variables and personalize them.
Scope: dyslexia specific. Causal status: intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0032023visual_attentionconfidence high
Visual attention span deficit in developmental dyslexia: A meta-analysis
Evidence type: meta analysis
Visual attention span performance is on average poorer in dyslexic groups, with substantial moderation by task, stimulus type, writing system and comparison group.
Design implication: Support reduced simultaneous visual load and test personalization rather than assuming one universal visual span.
Scope: dyslexia specific. Causal status: risk marker, causality not established. Audit date: 2026-10-05.
Open primary or indexed sourceE0042023visual_attentionconfidence high
Visual attention span capacity in developmental dyslexia: A meta-analysis
Evidence type: meta analysis
Dyslexic readers show lower mean visual attention span scores and greater individual variability than typical readers.
Design implication: Treat reader variability as a first class design requirement. Adaptive settings are preferable to a single preset.
Scope: dyslexia specific. Causal status: risk marker, debated theory. Audit date: 2026-10-05.
Open primary or indexed sourceE0052021orthographic_processingconfidence high
Is orthographic knowledge a strength or a weakness in individuals with dyslexia?
Evidence type: meta analysis
Orthographic knowledge is substantially weaker in dyslexic readers than chronological age peers, while the difference is much smaller against reading level matched controls.
Design implication: Preserve familiar letter skeletons and word forms. Excessively novel glyphs may add orthographic learning burden.
Scope: dyslexia specific. Causal status: associated deficit. Audit date: 2026-10-05.
Open primary or indexed sourceE0062012phonologyconfidence high
Phonological skills and their role in learning to read
Evidence type: meta analytic review
Phonemic awareness shows a large group difference between dyslexic and age matched typical readers and remains a strong correlate of word reading.
Design implication: Typography cannot replace phonological support. A reading system should optionally integrate text to speech, syllable or phoneme support and explicit decoding aids.
Scope: dyslexia specific. Causal status: strong risk factor and predictor. Audit date: 2026-10-05.
Open primary or indexed sourceE0072015cognitionconfidence high
Reading disabilities in children: A selective meta-analysis of the cognitive literature
Evidence type: meta analysis
Children with reading disabilities show group differences across rapid naming, phonological awareness, working memory, short term memory, visual spatial memory and executive processing.
Design implication: Reduce unnecessary memory and navigation demands. Reading support should minimize simultaneous task load.
Scope: mixed or general reading evidence. Causal status: mixed risk markers and associated deficits. Audit date: 2026-10-05.
Open primary or indexed sourceE0082009working_memoryconfidence high
Working memory, short-term memory, and reading disabilities
Evidence type: meta analysis
Children with reading disabilities show moderate disadvantages in short term and working memory, especially tasks with verbal and phonological storage demands.
Design implication: Prefer short visual chunks, stable context, visible progress and low memory dependent navigation.
Scope: mixed or general reading evidence. Causal status: associated deficit. Audit date: 2026-10-05.
Open primary or indexed sourceE0092010executive_functionconfidence moderate
Do tasks make a difference? Executive function and reading difficulties
Evidence type: meta analysis
Executive function differences occur in children with reading difficulties, but effects vary substantially with task demands and definitions.
Design implication: Avoid interfaces that require frequent switching, inhibition or remembering multiple reading controls at once.
Scope: mixed or general reading evidence. Causal status: associated deficit, heterogeneous. Audit date: 2026-10-05.
Open primary or indexed sourceE0102020auditory_processingconfidence moderate
Auditory processing deficit in individuals with dyslexia
Evidence type: meta analysis
Mismatch negativity studies show small to moderate group differences in auditory speech processing in children and adults with dyslexia.
Design implication: Optional audio support may help some readers but should not be assumed to address a universal auditory deficit.
Scope: dyslexia specific. Causal status: associated sensory marker, not universal. Audit date: 2026-10-05.
Open primary or indexed sourceE0112010visual_motionconfidence moderate
Coherence motion perception in developmental dyslexia
Evidence type: meta analysis
Motion coherence perception differs on average between dyslexic and control groups, but the relationship to continuous reading ability is much smaller.
Design implication: Do not use magnocellular or motion theories as the primary font design foundation.
Scope: dyslexia specific. Causal status: associated marker, weak evidence for direct reading causality. Audit date: 2026-10-05.
Open primary or indexed sourceE0122021procedural_learningconfidence moderate
Is a procedural learning deficit a causal risk factor for developmental language disorder or dyslexia?
Evidence type: meta analytic review
Evidence does not adequately support a generalized procedural learning deficit as a causal explanation of dyslexia.
Design implication: Do not build typography around a generalized procedural learning theory.
Scope: dyslexia specific. Causal status: uncertain theory. Audit date: 2026-10-05.
Open primary or indexed sourceE0132019crowdingconfidence moderate_high
Is excessive visual crowding causally linked to developmental dyslexia?
Evidence type: multi experiment longitudinal and intervention study
Excessive visual crowding was observed in dyslexic children at unattended locations, spacing improved accuracy, and prereading crowding predicted later poor reading.
Design implication: Provide adjustable spacing and reduce adjacent visual clutter, while preserving clear word boundaries.
Scope: dyslexia specific. Causal status: possible contributing risk factor. Audit date: 2026-10-05.
Open primary or indexed sourceE0142002crowdingconfidence moderate
Crowding effects on word identification in developmental dyslexia
Evidence type: controlled experiments
Dyslexic readers were more sensitive to surrounding visual material and moderate interletter spacing improved vocal reaction time in the dyslexic group.
Design implication: Spacing is a testable control variable, not a universal fixed value.
Scope: dyslexia specific. Causal status: associated visual processing difference. Audit date: 2026-10-05.
Open primary or indexed sourceE0152012spacingconfidence moderate
Extra-large letter spacing improves reading in dyslexia
Evidence type: controlled reading experiment
Extra large letter spacing improved reading performance in Italian and French dyslexic children in the tested conditions.
Design implication: Include wider spacing as a candidate setting, but test it against coupled word spacing and individual response.
Scope: dyslexia specific. Causal status: display intervention. Audit date: 2026-10-05.
Open primary or indexed sourceE0162020spacingconfidence high
Inter-letter spacing, inter-word spacing, and font with dyslexia-friendly features
Evidence type: controlled factorial experiment
Specialist letterforms did not improve reading. Increased interletter spacing without adequate interword spacing reduced reading speed.
Design implication: Optimize letter spacing and word spacing jointly. Never increase one independently by default.
Scope: dyslexia specific. Causal status: display intervention. Audit date: 2026-10-05.
Open primary or indexed sourceE0172016spacingconfidence high
Interword and interletter spacing effects during reading revisited
Evidence type: controlled eye movement experiments
The effect of letter spacing depends on the font default and interacts with interword spacing.
Design implication: Store spacing in relative font metrics and evaluate word segmentation, not only raw tracking values.
Scope: mixed or general reading evidence. Causal status: general reading mechanism. Audit date: 2026-10-05.
Open primary or indexed sourceE0182016spacingconfidence high
A Special Font for People with Dyslexia: Does it Work and, if so, why?
Evidence type: controlled experiment
A reported Dyslexie speed advantage disappeared when Arial was matched for within word and between word spacing.
Design implication: Separate glyph shape effects from spacing effects in every experiment.
Scope: dyslexia specific. Causal status: display intervention decomposition. Audit date: 2026-10-05.
Open primary or indexed sourceE0192017fontconfidence high
Dyslexie font does not benefit reading in children with or without dyslexia
Evidence type: controlled experiments
Children with dyslexia did not read Dyslexie faster or more accurately than Arial, and most preferred Arial.
Design implication: Do not equate subjective specialist appearance with measurable benefit. Familiarity matters.
Scope: dyslexia specific. Causal status: display intervention. Audit date: 2026-10-05.
Open primary or indexed sourceE0202022fontconfidence moderate_high
Does a specialist typeface affect how fluently children process letters, words, and passages?
Evidence type: controlled experiment
When spacing was controlled, Dyslexie did not improve word or passage reading versus Calibri, although rapid letter naming was somewhat more fluent.
Design implication: Distinctive glyphs may help letter identification without necessarily improving passage reading. Test both levels separately.
Scope: dyslexia specific. Causal status: display intervention. Audit date: 2026-10-05.
Open primary or indexed sourceE0212006font_sizeconfidence moderate
The effect of print size on reading speed in dyslexia
Evidence type: controlled psychophysical experiment
Dyslexic children required larger critical print sizes to reach maximum reading speed than reading ability matched controls in this study.
Design implication: Include print size or x height in personalization. Do not assume conventional point size is equivalent across fonts.
Scope: dyslexia specific. Causal status: display interaction. Audit date: 2026-10-05.
Open primary or indexed sourceE0222018eye_movementconfidence moderate
Effect of different font sizes and of spaces between words on eye movement performance
Evidence type: eye tracking experiment
Larger and more spaced text reduced fixation duration in both dyslexic and non dyslexic children in the tested material.
Design implication: Use fixation duration as an optimization signal, not as a diagnostic cause. Test size and spacing together.
Scope: dyslexia specific. Causal status: outcome biomarker. Audit date: 2026-10-05.
Open primary or indexed sourceE0232026eye_movementconfidence moderate_high
AI-enabled eye-movement and emerging multimodal frameworks for precision dyslexia screening
Evidence type: systematic review
Dyslexic readers commonly show longer fixation durations, more regressions and lower saccadic efficiency, but machine learning studies are heterogeneous and often at risk of overfitting.
Design implication: Use gaze features to evaluate adaptation and reader load. Never infer a clinical diagnosis from a single reading session.
Scope: dyslexia specific. Causal status: biomarker, not established cause. Audit date: 2026-10-05.
Open primary or indexed sourceE0242015eye_movementconfidence moderate
Evaluation of ocular movements in patients with dyslexia
Evidence type: eye movement study
Reading related saccade and regression differences were present, while basic tracking saccades were not significantly different, supporting the interpretation that many reading eye movement abnormalities may be secondary to linguistic processing difficulty.
Design implication: Do not design a font around the assumption of primary oculomotor dysfunction.
Scope: dyslexia specific. Causal status: likely downstream biomarker in many cases. Audit date: 2026-10-05.
Open primary or indexed sourceE0252016colorconfidence high
The effect of coloured overlays and lenses on reading
Evidence type: systematic review
Higher quality evidence does not support colored overlays or lenses as a general treatment for reading difficulty or dyslexia.
Design implication: Do not prescribe colored backgrounds as a default dyslexia feature. Allow user preference without therapeutic claims.
Scope: dyslexia specific. Causal status: intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0262021orthographyconfidence high
Orthographic depth and developmental dyslexia
Evidence type: systematic review and meta analysis
Orthographic depth moderates some manifestations of dyslexia, while reading speed remains a reliable discriminator across European orthographies.
Design implication: Font and reading algorithms must be language and writing system aware. English results cannot simply be universalized.
Scope: dyslexia specific. Causal status: moderator. Audit date: 2026-10-05.
Open primary or indexed sourceE0272026cross_linguistic_neuroscienceconfidence high
Culture Shapes the Neural Functional Alteration and Its Development in Children With Dyslexia
Evidence type: meta analysis
Across Chinese, English and German, dyslexia showed shared hypoactivation in left fusiform and inferior parietal regions, alongside language specific differences.
Design implication: There are shared reading network constraints, but optimization needs script specific models and test corpora.
Scope: dyslexia specific. Causal status: neural correlate. Audit date: 2026-10-05.
Open primary or indexed sourceE0282026neuroscienceconfidence moderate_high
Functional Connectivity Alterations in Developmental Dyslexia
Evidence type: functional connectivity meta analysis
Reduced functional connectivity between left inferior frontal and left fusiform regions was found across task and resting state studies.
Design implication: The product should optimize fluent visual word recognition and language integration, but neural findings do not specify a single glyph shape.
Scope: dyslexia specific. Causal status: neural correlate. Audit date: 2026-10-05.
Open primary or indexed sourceE0292026neuroscienceconfidence moderate_high
Neuroimaging meta-analyses of phonological awareness deficits in children with developmental dyslexia
Evidence type: neuroimaging meta analysis
Children with dyslexia showed reduced activation in left inferior temporal and occipital regions during phonological awareness tasks.
Design implication: Visual and phonological processes interact. Reading support should be multimodal rather than purely typographic.
Scope: dyslexia specific. Causal status: neural correlate. Audit date: 2026-10-05.
Open primary or indexed sourceE0302022neuroplasticityconfidence high
Reading intervention and neuroplasticity
Evidence type: systematic review and meta analysis
Reading intervention studies report brain changes across distributed reading and domain general systems, but the quantitative meta analysis did not find a single consistent activation change.
Design implication: Avoid simplistic normalize the dyslexic brain claims. Measure behavioral outcomes directly.
Scope: mixed or general reading evidence. Causal status: intervention response. Audit date: 2026-10-05.
Open primary or indexed sourceE0312010morphologyconfidence high
A meta-analysis of morphological interventions
Evidence type: meta analysis
Morphological instruction produced a small positive overall effect on literacy outcomes in learners with literacy difficulties, with effects across phonological awareness, morphology, vocabulary, comprehension and spelling.
Design implication: An advanced reading system can optionally expose meaningful morpheme structure, especially for complex words, but should test cognitive load.
Scope: mixed or general reading evidence. Causal status: intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0322022interventionconfidence high
A Meta-Analysis of Phonemic Awareness Instruction
Evidence type: meta analysis
Phonemic awareness instruction has positive effects for children suspected of reading disability, especially segmentation and composite outcomes.
Design implication: If the product extends beyond typography, phoneme and grapheme support has a stronger evidence basis than a specialist font alone.
Scope: mixed or general reading evidence. Causal status: intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0332022populationconfidence high
Prevalence of Developmental Dyslexia in Primary School Children
Evidence type: systematic review and meta analysis
Pooled prevalence of developmental dyslexia in primary school children was about 7.1 percent, with no significant pooled prevalence difference across alphabetic versus logographic scripts or shallow versus deep orthographies.
Design implication: Design for a large and globally diverse user population, not a niche visual style.
Scope: dyslexia specific. Causal status: epidemiology. Audit date: 2026-10-05.
Open primary or indexed sourceE0342026perceptual_spanconfidence moderate_high
Reduced perceptual span in dyslexic children: a gaze-contingent eye-tracking study
Evidence type: gaze contingent eye tracking study
Children with dyslexia showed greater foveal load and reduced parafoveal processing in a moving window reading task. Window size affected their reading speed less than controls, consistent with a smaller effective perceptual span.
Design implication: Do not assume that showing more upcoming text is always useful. Test whether reducing visible peripheral text or visual clutter improves efficiency for a specific reader.
Scope: dyslexia specific. Causal status: downstream biomarker or contributing mechanism. Audit date: 2026-10-05.
Open primary or indexed sourceE0352024perceptual_spanconfidence moderate
The perceptual span in dyslexic reading and visual search
Evidence type: moving window eye tracking study
Evidence for a reduced perceptual span in dyslexic adult reading was equivocal, and there was no evidence for a smaller perceptual span in visual search, although search accuracy and saccade amplitudes differed.
Design implication: Perceptual span should be measured per reader rather than assumed from diagnosis.
Scope: dyslexia specific. Causal status: mixed biomarker evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0362024parafoveal_processingconfidence moderate_high
Parafoveal Processing and Transposed-Letter Effects in Developmental Dyslexic Reading
Evidence type: boundary paradigm eye tracking study
Dyslexic children obtained parafoveal preview benefit and encoded letter identity separately from letter position, but later measures suggested reduced sensitivity to initial letter transpositions.
Design implication: Preserve strong initial letter identity cues and avoid typography that makes first letter position harder to discriminate.
Scope: dyslexia specific. Causal status: processing characteristic. Audit date: 2026-10-05.
Open primary or indexed sourceE0372022parafoveal_processingconfidence moderate_high
Parafoveal processing and transposed-letter effects in dyslexic reading
Evidence type: boundary paradigm eye tracking study
Adults with dyslexia showed parafoveal orthographic preview benefits, but early positional encoding of initial letters differed from skilled readers.
Design implication: Initial character clarity and stable letter position cues deserve explicit testing in adaptive glyph design.
Scope: dyslexia specific. Causal status: processing characteristic. Audit date: 2026-10-05.
Open primary or indexed sourceE0382010lexical_processingconfidence moderate_high
Word length and word frequency affect eye movements in dyslexic children reading in a regular German orthography
Evidence type: eye movement experiment
In German dyslexic children, fixation durations and saccade counts increased with word length and frequency difficulty, and regressions increased for low frequency words.
Design implication: Calibration texts must manipulate word length and lexical frequency independently because typography effects may change with lexical difficulty.
Scope: dyslexia specific. Causal status: task dependent processing marker. Audit date: 2026-10-05.
Open primary or indexed sourceE0391995lexical_processingconfidence moderate_high
Eye fixation patterns among dyslexic and normal readers: effects of word length and word frequency
Evidence type: eye movement experiment
Long and low frequency words increased gaze duration, reinspection time, and fixation count in dyslexic and younger reading level controls. The pattern supported lexical processing difficulty rather than a unique oculomotor deficit.
Design implication: Use lexical difficulty as a covariate when interpreting eye movement differences.
Scope: dyslexia specific. Causal status: processing marker. Audit date: 2026-10-05.
Open primary or indexed sourceE0402025lexical_processingconfidence moderate
Eye Movements of French Dyslexic Adults While Reading Texts
Evidence type: eye tracking study
French adults with dyslexia made more errors and more progressive and regressive fixations, with worse performance for meaningless text, suggesting greater reliance on semantic context during difficult reading.
Design implication: Test reading support under both supportive semantic context and low context material because an aid can appear effective only when context compensates for decoding difficulty.
Scope: dyslexia specific. Causal status: processing characteristic. Audit date: 2026-10-05.
Open primary or indexed sourceE0412025eye_voice_spanconfidence moderate
An In-Depth Investigation of Eye Movement Profile of Dyslexic Readers Using a Standardized Text-Reading Aloud Task in French
Evidence type: eye tracking and oral reading study
Adults with dyslexia showed persistent word length effects and a reduced and unstable eye voice span during oral reading, consistent with continued reliance on sublexical decoding.
Design implication: For oral reading support, measure eye voice coordination and not only gaze metrics.
Scope: dyslexia specific. Causal status: downstream processing biomarker. Audit date: 2026-10-05.
Open primary or indexed sourceE0422021text_adaptationconfidence moderate_high
An experimental eye-tracking study of text adaptation for readers with dyslexia
Evidence type: eye tracking experiment
Visual support and lexical simplification facilitated sentence processing. Benefits from lexical simplification were larger for readers with lower print exposure and smaller vocabularies.
Design implication: Adaptive reading should be able to change lexical difficulty and add optional semantic support, but should personalize by vocabulary and print exposure.
Scope: dyslexia specific. Causal status: intervention effect. Audit date: 2026-10-05.
Open primary or indexed sourceE0432015perceptual_spanconfidence moderate_high
Individual differences in the perceptual span during reading
Evidence type: moving window eye tracking study
In general readers, perceptual span size was associated with language ability rather than oculomotor processing speed.
Design implication: Treat perceptual span partly as a consequence of language processing efficiency, not merely a visual capacity.
Scope: mixed or general reading evidence. Causal status: general reading mechanism. Audit date: 2026-10-05.
Open primary or indexed sourceE0441986perceptual_spanconfidence moderate
Eye movements and the perceptual span in beginning and skilled readers
Evidence type: developmental eye tracking experiment
Perceptual span changes with reading proficiency and text difficulty, and a smaller span was not sufficient to explain slower beginning reading.
Design implication: Do not infer that a small span is itself the primary cause of poor reading. Optimize foveal processing and linguistic accessibility too.
Scope: mixed or general reading evidence. Causal status: general reading mechanism. Audit date: 2026-10-05.
Open primary or indexed sourceE0452024script_specific_processingconfidence moderate
Language-universal and script-specific factors in the recognition of letters in visual crowding
Evidence type: visual crowding experiment
In Hebrew readers, crowded letter recognition reflected both general lexical effects and script specific transitional probability effects tied to right to left reading direction.
Design implication: Confusability, contextual letter probability, and reading direction must be modeled separately for each script.
Scope: mixed or general reading evidence. Causal status: moderator. Audit date: 2026-10-05.
Open primary or indexed sourceE0462023comorbidityconfidence moderate
Effects of word length and word frequency among dyslexic, ADHD-I and typical readers
Evidence type: comparative eye tracking study
Children with dyslexia and children with inattentive ADHD showed different cognitive, linguistic, word length, and word frequency patterns, supporting the need to distinguish overlapping conditions.
Design implication: Do not treat attentional difficulty as synonymous with dyslexia. Calibration should identify performance patterns without diagnosing comorbidity.
Scope: dyslexia specific. Causal status: moderator. Audit date: 2026-10-05.
Open primary or indexed sourceE0472022spacingconfidence high
The effect of inter-letter spacing on reading performance and eye movements in typically reading and dyslexic children
Evidence type: eye tracking reading experiment
Increased interletter spacing did not improve reading speed, accuracy, or comprehension in dyslexic or typical children, although condensed spacing increased fixation duration and wider spacing shortened fixations in dyslexic children.
Design implication: A gaze improvement alone is insufficient evidence of better reading. Spacing must be judged against speed, accuracy, and comprehension together.
Scope: dyslexia specific. Causal status: intervention effect with mixed outcomes. Audit date: 2026-10-05.
Open primary or indexed sourceE0482018spacingconfidence moderate
Influence of increased letter spacing and font type on the reading ability of dyslexic children
Evidence type: font and spacing experiment
Dyslexie did not outperform other fonts, while increased letter spacing improved performance and could remove disadvantages seen with less readable fonts.
Design implication: Treat font form and spacing as separable factors. Spacing can sometimes compensate for poor font choices but should not justify a poor base design.
Scope: dyslexia specific. Causal status: intervention effect. Audit date: 2026-10-05.
Open primary or indexed sourceE0492013fontconfidence moderate
Good fonts for dyslexia
Evidence type: within subject eye tracking experiment
In one study of adults with dyslexia, sans serif, monospaced, and roman styles were associated with better performance than serif, proportional, and italic alternatives. These findings are not sufficient to establish universal font rules.
Design implication: Use sans serif and upright styles as useful starting priors, not hard constraints. Re test within each reader and language.
Scope: dyslexia specific. Causal status: intervention evidence, limited replication. Audit date: 2026-10-05.
Open primary or indexed sourceE0502005fontconfidence moderate_high
Serifs and font legibility
Evidence type: controlled font feature experiment
When serif size was isolated experimentally, serif presence produced little or no meaningful difference in continuous reading speed in normally sighted readers.
Design implication: Do not encode serif versus sans serif as a universal causal rule. Specific glyph geometry matters more than the category label alone.
Scope: mixed or general reading evidence. Causal status: general reading intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0512011font_sizeconfidence high
Does print size matter for reading? A review of findings from vision science and typography
Evidence type: vision science review
Reading speed typically rises with print size until a critical print size and then plateaus across a broad fluent range. Angular x height is a more meaningful visual measure than nominal point size.
Design implication: Store and calibrate visual angle and x height, not only CSS pixels or points.
Scope: mixed or general reading evidence. Causal status: general reading mechanism. Audit date: 2026-10-05.
Open primary or indexed sourceE0522007displayconfidence moderate_high
Text-background polarity affects performance irrespective of ambient illumination and colour contrast
Evidence type: controlled display experiment
Proofreading performance was better with dark text on a light background than the reverse under the tested conditions, while color contrast could not substitute for luminance contrast.
Design implication: Maintain strong luminance contrast. Positive polarity is a useful default prior but should remain user configurable.
Scope: mixed or general reading evidence. Causal status: general display intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0532009displayconfidence moderate_high
The advantage of positive text-background polarity is due to high display luminance
Evidence type: controlled display experiment
When overall display luminance was equated, the usual positive polarity advantage disappeared, suggesting that luminance is an important mechanism behind polarity effects.
Design implication: Model actual luminance and contrast rather than treating dark mode versus light mode as a categorical rule.
Scope: mixed or general reading evidence. Causal status: general display mechanism. Audit date: 2026-10-05.
Open primary or indexed sourceE0542017displayconfidence moderate
Effects of ambient illumination, contrast polarity, and letter size on text legibility under glance-like reading
Evidence type: legibility threshold experiment
Negative polarity under dark ambient illumination produced worse glance like word legibility, with effects interacting with letter size and illumination.
Design implication: Reading presets should account for ambient conditions and effective size, not just background color.
Scope: mixed or general reading evidence. Causal status: general display intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0552021colorconfidence low_moderate
The Relation between Physiological Parameters and Colour Modifications in Text Background and Overlay during Reading
Evidence type: multimodal physiological reading experiment
A small study found some color conditions associated with shorter reading duration in dyslexic children, but the design does not override higher level systematic review evidence showing no general treatment effect for colored overlays.
Design implication: Color can be personalized for comfort or tested empirically, but must not be prescribed as a dyslexia treatment.
Scope: dyslexia specific. Causal status: possible individual preference effect. Audit date: 2026-10-05.
Open primary or indexed sourceE0562026font_variabilityconfidence moderate
Designing a Variable Typeface for Dyslexia-Friendly Reading
Evidence type: variable typeface design and empirical testing study
A recent variable typeface study reported that not all conventional dyslexia font features improved performance and argued for adjustable simple to complex letterforms and individual adaptation.
Design implication: Build variability into the font architecture rather than shipping one immutable dyslexia style.
Scope: dyslexia specific. Causal status: design intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0572026cross_linguisticconfidence high
Linguistic correlates of Chinese children with developmental dyslexia
Evidence type: systematic review and meta analysis
In Chinese children with developmental dyslexia, large group differences were reported in morphological awareness, phonological awareness, orthographic awareness, and rapid automatized naming, with moderate short term memory differences.
Design implication: A Latin alphabet font model cannot be generalized to Chinese. Morphology, character structure, and orthographic awareness require script specific logic.
Scope: dyslexia specific. Causal status: cross linguistic correlates. Audit date: 2026-10-05.
Open primary or indexed sourceE0582022cross_linguisticconfidence high
The Percentages of Cognitive Skills Deficits among Chinese Children with Developmental Dyslexia
Evidence type: systematic review and meta analysis
Among Chinese children with developmental dyslexia, no single cognitive deficit characterized all readers. Rapid automatized naming deficits had the highest pooled prevalence among measured skills at about 44 percent.
Design implication: Never assume a universal cognitive subtype. The engine should infer useful settings from observed reading response, not diagnosis labels.
Scope: dyslexia specific. Causal status: heterogeneity evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0592019orthographyconfidence high
A meta-analysis of reading-level match dyslexia studies in consistent alphabetic orthographies
Evidence type: meta analysis
In highly consistent alphabetic orthographies, reading level matched dyslexic children did not consistently differ in rapid naming, phonological memory, or auditory temporal processing, while phoneme manipulation differences remained.
Design implication: Orthographic consistency changes which deficits are most discriminative. Parameter priors must be language aware.
Scope: dyslexia specific. Causal status: moderator and theory constraint. Audit date: 2026-10-05.
Open primary or indexed sourceE0602025rapid_namingconfidence moderate_high
Rapid automatized naming: what it is, what it is not, and why it matters
Evidence type: scholarly review
Rapid automatized naming is an important indicator of reading fluency difficulty, but it reflects coordinated processes rather than a single elementary deficit.
Design implication: Use naming fluency to characterize reading automaticity, not as a direct typography prescription.
Scope: mixed or general reading evidence. Causal status: predictor and composite processing marker. Audit date: 2026-10-05.
Open primary or indexed sourceE0612002word_shapeconfidence moderate
Does whole-word shape play a role in visual word recognition?
Evidence type: lexical decision experiments
Distorting overall word outline affected lower frequency words more strongly, but results did not support a simple whole word shape theory of recognition.
Design implication: Preserve local letter identity and orthographic coding rather than designing primarily around global word silhouettes.
Scope: mixed or general reading evidence. Causal status: general visual word recognition evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0622021font_widthconfidence moderate_high
The effect of font width on eye movements during reading
Evidence type: eye tracking typography experiment
Large changes in font width altered fixation and saccade patterns even when overall reading speed remained similar, indicating eye movement tradeoffs rather than a simple wider is better rule.
Design implication: Font width should be optimized jointly with spacing and line length. Eye movement changes alone are not proof of improved reading.
Scope: mixed or general reading evidence. Causal status: general typography intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0632025font_emphasisconfidence moderate_high
To boldly go where no text has gone before: The effects of boldface letters on eye movements in reading
Evidence type: eye tracking reading experiment
Bolding the first half of every word, as used by Bionic Reading style systems, did not improve reading and produced costs compared with normal unbolded text.
Design implication: Do not assume that partial bolding guides optimal fixation or word recognition. Any emphasis algorithm needs direct evidence.
Scope: mixed or general reading evidence. Causal status: general typography intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0642012display_qualityconfidence moderate_high
Reading on LCD vs e-Ink displays: effects on fatigue and visual strain
Evidence type: extended reading experiment
Extended reading on modern LCD and electronic ink displays produced similar subjective and objective fatigue when image quality was comparable, suggesting display quality matters more than technology label alone.
Design implication: Optimize resolution, rendering, contrast, and visual size instead of assuming electronic ink is inherently superior.
Scope: mixed or general reading evidence. Causal status: general display intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0651989display_qualityconfidence moderate
Effects of VDT resolution on visual fatigue and readability
Evidence type: reading fatigue and eye movement experiment
Higher display resolution particularly improved readability for very small characters, while differences were minimal for sufficiently large characters.
Design implication: Rendering quality becomes especially important near or below critical print size. Small text should trigger stronger anti aliasing and minimum size safeguards.
Scope: mixed or general reading evidence. Causal status: general display intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0662019web_typographyconfidence moderate_high
Investigating Effects of Typographic Variables on Webpage Reading Through Eye Movements
Evidence type: eye tracking clinical trial
Multiple realistic webpage typographic variables affected eye movements and reading performance across children and adults with and without dyslexia, with many effects shared across groups.
Design implication: Many good readability changes are universal rather than dyslexia exclusive. Build a high quality reading system first, then personalize where group or individual effects diverge.
Scope: dyslexia specific. Causal status: intervention evidence. Audit date: 2026-10-05.
Open primary or indexed sourceE0672026visual_oculomotorconfidence high
Visual and Oculomotor Function in Developmental Dyslexia: A Systematic Review and Meta-Analysis
Evidence type: systematic review and meta analysis
Across 26 studies, dyslexic groups showed several binocular and oculomotor differences, including more fixations, longer fixation durations, more regressions and reduced saccade amplitude, while visual acuity and refractive error did not significantly differ.
Design implication: Use eye movement and visual effort measures as validation signals, but do not design the font around a claim that dyslexia is a primary acuity or refractive disorder.
Scope: dyslexia specific. Causal status: associated visual and oculomotor differences, clinical relevance still being clarified. Audit date: .
Open primary or indexed sourceE0682026visual_word_recognitionconfidence moderate_high
Are letter identity and letter order encoding functionally separable? Evidence from masked priming with visual similarity and letter transpositions
Evidence type: masked priming experiments
Recent visual word recognition experiments continue to show that letter identity and letter order are constrained by visual similarity during early processing.
Design implication: Protect distinctive local letter identity cues and avoid unnecessary visual similarity among confusable glyphs.
Scope: general reading evidence. Causal status: general visual word recognition mechanism. Audit date: .
Open primary or indexed sourceE0692021font_familiarityconfidence moderate
You read best what you read most: An eye tracking study
Evidence type: eye tracking study
Typeface familiarity influenced reading speed, supporting the value of familiar letter structures rather than novelty for its own sake.
Design implication: Preserve familiar humanist Latin skeletons and make differentiation local rather than globally unusual.
Scope: general reading evidence. Causal status: general reading intervention evidence. Audit date: .
Open primary or indexed sourceE0702014letter_recognitionconfidence moderate
Investigating letter recognition in the brain by varying typeface: an event-related potential study
Evidence type: ERP experiment
Typeface fluency affected both early and later stages of letter processing even when the task required abstract letter identity.
Design implication: Avoid unnecessarily disfluent or decorative letter construction in a reading typeface.
Scope: general reading evidence. Causal status: general letter recognition mechanism. Audit date: .
Open primary or indexed sourceE0712018letter_similarityconfidence moderate_high
Visual letter similarity effects during sentence reading: Evidence from the boundary technique
Evidence type: boundary paradigm eye tracking study
Visual letter similarity in parafoveal preview measurably affected early word processing during sentence reading.
Design implication: Treat visual confusability as a genuine variable and preserve high identity contrast in critical glyph pairs.
Scope: general reading evidence. Causal status: general visual word recognition mechanism. Audit date: .
Open primary or indexed sourceE0722016letter_featuresconfidence moderate
The role of letter features in visual-word recognition: Evidence from a delayed segment technique
Evidence type: lexical decision experiments
Different components of letters contribute unequally to word identification, with midsegments and junction structure carrying important information.
Design implication: Do not concentrate all differentiation in decorative terminals. Preserve informative internal structure, junctions and midsegments.
Scope: general reading evidence. Causal status: general visual word recognition mechanism. Audit date: .
Open primary or indexed sourceE0732020typographic_rhythmconfidence moderate
The Influence of Typography on Algorithms that Predict the Speed and Comfort of Reading
Evidence type: typography and visual comfort study
Font design, weight, x height relative to line separation, expansion and compression can alter spatial regularity measures associated with likely reading speed and visual comfort.
Design implication: Avoid overly periodic vertical stroke rhythms and treat weight, x height and line spacing as interacting variables.
Scope: general reading evidence. Causal status: general typography mechanism. Audit date: .
Open primary or indexed sourceE0741998display_legibilityconfidence moderate
High and low luminance letters, acuity reserve, and font effects on reading speed
Evidence type: controlled reading experiment
At high luminance there was no reading rate difference between the serif and sans serif fonts tested, while low luminance favoured the sans serif font in that experiment.
Design implication: Screen and luminance conditions can interact with font design. Protect simple outlines and sufficient acuity reserve at small sizes.
Scope: general reading evidence. Causal status: general display interaction. Audit date: .
Open primary or indexed sourceE0752018colorconfidence high
Efficacy of coloured overlays and lenses for treating reading difficulty: an overview of systematic reviews
Evidence type: overview of systematic reviews
Across systematic reviews there is not a reliable evidence base for recommending coloured overlays or lenses for reading difficulty or discomfort.
Design implication: Keep color as a comfort and brand preference, not a dyslexia treatment claim.
Scope: reading difficulty evidence. Causal status: intervention evidence. Audit date: .
Open primary or indexed sourceE0762011letter_identificationconfidence moderate_high
Alphabetic letter identification: effects of perceivability, similarity, and bias
Evidence type: review plus experiments
Letter identification performance reflects perceivability, visual similarity and response bias, providing a framework for evaluating confusable characters.
Design implication: Treat confusability pairs as measurable recognition problems rather than aesthetic preferences.
Scope: general visual recognition evidence. Causal status: general visual letter recognition mechanism. Audit date: .
Open primary or indexed sourceE0772024spacingconfidence moderate
Increasing inter-word spacing reduces migration errors and improves reading comprehension in students with dyslexia
Evidence type: controlled reading experiment
Increasing inter-word spacing improved standardized reading comprehension in students with dyslexia and reduced reported letter and word migration errors in the tested texts.
Design implication: Increase word boundary salience cautiously in the Reading cut while avoiding exaggerated global tracking.
Scope: dyslexia specific. Causal status: intervention effect. Audit date: .
Open primary or indexed sourceE0782022letter_recognitionconfidence high
Closed letter counters impair recognition
Evidence type: controlled psychophysical experiment
Closed apertures impaired identification of letters including a, c, e, r, s, t and f, including parafoveal conditions and crowding.
Design implication: Protect open apertures and counters, especially in the Reading cut and heavier weights.
Scope: general reading evidence. Causal status: general visual recognition mechanism. Audit date: .
Open primary or indexed sourceE0792019font_weightconfidence high
Smaller visual angles show greater benefit of letter boldness than larger visual angles
Evidence type: controlled recognition experiment
Thin strokes and extreme boldness reduced recognition, while moderate additional boldness provided more benefit at smaller visual angles.
Design implication: Use Regular as the main reading weight, offer Medium for small visual sizes, and avoid extreme body-text weights.
Scope: general reading evidence. Causal status: general visual recognition mechanism. Audit date: .
Open primary or indexed sourceE0802022stroke_contrastconfidence moderate_high
The dispute about sans serif versus serif fonts: An interaction between the variables of serif and stroke contrast
Evidence type: controlled word recognition experiment
Typeface performance depended on the interaction between serif presence and stroke contrast rather than a simple serif versus sans-serif category rule.
Design implication: Keep the approved low-contrast sans structure, rather than relying on a categorical sans-serif claim.
Scope: general reading evidence. Causal status: general typography mechanism. Audit date: .
Open primary or indexed sourceE0812022font_widthconfidence high
Fonts of wider letter shapes improve letter recognition in parafovea and periphery
Evidence type: controlled parafoveal and peripheral recognition experiments
Wider letter shapes improved target letter recognition and reduced neighbouring-letter misreadings relative to narrower forms in parafoveal and peripheral presentation.
Design implication: Use a subtle width increase in the Reading cut, not a globally expanded display design.
Scope: general reading evidence. Causal status: general visual recognition mechanism. Audit date: .
Open primary or indexed sourceE0822026typography_reviewconfidence high
Applying cognitive and perceptual science to typeface choices
Evidence type: peer reviewed review
Typeface legibility depends on reading scenario. The review highlights simple designs, open counters, non-condensed widths, adequate spacing and avoidance of extreme weights, while rejecting the idea of one universally most legible typeface.
Design implication: Use an optical family with a beautiful Display cut and a Reading cut rather than forcing one geometry into all contexts.
Scope: general reading evidence. Causal status: evidence synthesis. Audit date: .
Open primary or indexed source