Do kids with dyslexia or ADHD have visual processing problems?
Children with reading disorder struggled specifically with remembering the order of visual shapes, not with seeing or remembering single shapes, and this order memory modestly predicted reading skill.
Source
Visual processing in reading disorders and attention-deficit/hyperactivity disorder and its contribution to basic reading ability
Study at a glance
- Design
- Cross-sectional — Diagnostic-group comparison (MANCOVA controlling verbal IQ) on three visual perceptual subtests, plus hierarchical regressions predicting basic reading in the whole sample.
- N
- N=264 · 264 children: 51 with reading disorder, 88 with ADHD, 51 with both, and 74 typically developing controls.
- Population
- Community sample of children aged 8-12 in the United States
- Outcome
- Visual discrimination, visual memory for single figures, and visual sequential memory scores; basic reading (word reading and nonword decoding)
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
The researchers tested 264 children aged 8 to 12 from the community: 51 with a reading disorder, 88 with ADHD, 51 with both conditions, and 74 typically developing controls. Each child completed three untimed visual tests: matching complex figures (discrimination), recognising a single complex figure from memory, and recognising the correct order of a sequence of simple shapes. Groups were compared while controlling for verbal IQ, and regressions tested whether visual skills predicted basic reading after accounting for verbal IQ and either phonological awareness or spelling-pattern (orthographic) knowledge.
What they found
Children with reading disorder alone matched controls on visual discrimination and on memory for single figures, and children with ADHD alone matched controls on all three tests. Both groups with reading disorder did worse than controls on memory for shape sequences, whereas the ADHD-only group did not. The comorbid group was weaker on all three tests, which the authors linked to their greater attention problems rather than a separate visual deficit. Visual sequential memory was the only visual skill that predicted basic reading, adding only about 2 to 3% of explained variance beyond verbal IQ and phonological or orthographic skill.
The limits
What it doesn't show
The sample came from the community and had relatively mild reading disorder and ADHD, so clinic samples might show larger or broader deficits. Only three subtests from one test battery were used, and the sequence task used easily named shapes, so it cannot separate a pure memory-for-order problem from weaker verbal labelling. The design is correlational and measured at one time point, so it cannot show that poor sequential memory causes reading difficulty. The attention explanation for the comorbid group rests on follow-up correlations rather than a direct test.
Key terms
- Reading disorder (RD) / developmental dyslexia
- A persistent difficulty learning to read accurately and fluently that is not explained by low intelligence or lack of teaching.
- Comorbidity
- When two conditions occur together in the same person, such as reading disorder and ADHD.
- Phonological awareness
- The ability to notice and manipulate the sounds within words, for example removing one sound and saying what word remains.
- Orthographic processing
- Knowledge of how words are spelled and the ability to recognise correct spelling patterns, such as picking the real word over a sound-alike misspelling.
- Memory for order versus memory for item
- Remembering the sequence in which things appeared, as opposed to remembering which things appeared at all; these can be impaired separately.
- Hierarchical regression
- A regression where predictors are added in steps, so you can see how much extra variance a new predictor explains after earlier ones are controlled.
Flashcards
0 of 9 answers reviewed
Research intelligence for this paper
See its role on concept claims, tensions it is part of, placement history, and related discoveries.
Quiz yourself
Which group did NOT differ from controls on memory for the order of shapes?
Common questions
Does this mean dyslexia is a visual problem?
Not in general. Children with reading disorder saw and remembered single figures normally; their weakness was specific to remembering the order of shapes, which may reflect sequencing or verbal labelling rather than vision itself.
Why was the group with both conditions worse at everything?
The authors think their extra attention problems made all tasks harder, because the visual scores correlated with attention ratings and the groups did not differ on another visual task that minimised attention demands.
Why include an ADHD group at all?
ADHD often co-occurs with reading disorder, so including it lets the researchers check whether a deficit belongs to reading disorder specifically or to attention problems.
More on Reading