Dyslexia and handedness: developmental phonological and surface dyslexias are associated with different biases for handedness.

Developmental disorders of reading and spelling have long been associated with increased left- and mixed-handedness but the evidence has been controversial. The right shift (RS) theory of handedness and cerebral dominance, developed by Annett from 1972 onward, offers resolutions to several puzzles about laterality in the so-called dyslexias. This review of findings in the light of the theory shows that "phonological" dyslexics are less likely to be right-handed, while "surface" or "dyseidetic" dyslexics are more likely to be right-handed than the general population.