Related Experiment Videos
(Con)text-specific effects of visual dysfunction on reading in posterior cortical atrophy.
Keir X X Yong1, Timothy J Shakespeare1, Dave Cash1
1Dementia Research Centre, Department of Neurodegeneration, UCL Institute of Neurology, University College London, London, UK.
Summary
Posterior cortical atrophy (PCA) patients exhibit significant reading deficits, performing worse than Alzheimer's patients and controls. Visual processing impairments, not universal reading failure, explain these context-specific difficulties.
Area of Science:
- Neuroscience
- Ophthalmology
- Cognitive Psychology
Background:
- Reading deficits are common in posterior cortical atrophy (PCA) but poorly understood.
- Single-word reading in PCA requires further characterization.
Purpose of the Study:
- To evaluate reading accuracy and speed in PCA patients compared to typical Alzheimer's disease (tAD) patients and healthy controls.
- To investigate the impact of perceptual properties on reading in PCA.
Main Methods:
- Assessed reading accuracy and speed of 26 PCA patients, 17 tAD patients, and 14 controls.
- Manipulated inter-letter spacing, font size, length, font type, case, and confusability in 192 single words.
Main Results:
- PCA patients were significantly less accurate and slower readers than tAD patients and controls.
- Increased letter spacing, size, length, and non-cursive fonts adversely affected PCA reading, with visual errors dominating.
- An inverse size effect (poorer reading of larger fonts) in PCA correlated with reduced grey matter in the right superior parietal lobule.
Conclusions:
- Reading impairments in PCA are linked to specific visual processing deficits (crowding, visuoperceptual, visuospatial), not a universal reading impairment.
- Deficits are context-specific, particularly for large, spaced, lengthy words.
- Findings aid in characterizing PCA-related dyslexia and developing reading aids.