The Relationships Between Motor Learning, the Visual System and Dyslexia

Abstract

Developmental dyslexia’s ‘Cerebellar Deficit Theory’ proposes that a subtle developmental cerebellar dysfunction leads to deficits in attaining ‘automatic’ procedures and manifests as subtle motor impairments (e.g., balance control, motor learning) along with reading and phonological difficulties. The ‘Magnocellular deficit’ and the ‘rapid visual’ theories suggest a specific deficit within the visual information processing system among dyslexic readers. Previously, we found the dyslexic readers to be inferior, as compared to their non-impaired reader peers, in their ability to acquire a novel set of hand movements while standing. In the current study, we explored the relationships between volitional and non-volitional motor learning, the visual system and dyslexia. We found the dyslexic readers to be slower and less accurate, as compared to skilled readers, in tasks that were ‘visually’ oriented and demanded reaction. However, in tasks that did not involve the visual system or when hand-eye coordination was needed rather than reaction, the groups’ performance did not differ. In addition, correlations between the performance in the visual and the motor learning tasks were found within the skill readers only. Overall, the results support the assumption that a deficit within the visual system is involved in the presumably inferior ability of the dyslexic readers to acquire a new movement.