Mental rotation of letters and shapes in developmental dyslexia.

Extending the work of Corballis et al (1985, Cortex 21 225-236), we investigated mental rotation of letters (experiment 1), and of letters and shapes (experiment 2) in normal readers and developmental dyslexics. Whereas the overall response times were equal for shapes in both groups, for letters they were slower in dyslexics. For letters as well as for shapes, however, the same mental-rotation effects were obtained between the groups. The results are interpreted as support for the notion of developmental dyslexia as a deficit in functional coordination between graphemic and phonological letter representations.