Hemispheric specialization for language in the congenitally blind: the influence of the Braille system

The functional cerebral organization of two groups of congenitally blind persons of different age and schooling was studied by testing their dichotic listening to pairs of digits. The younger congenitally blind group showed a comparable level of performance to their control counterparts; however, older subjects shifted their initial right ear advantage to an increased left ear performance as they progressed in the mastery of the Braille system. As this system is founded on spatial strategies, we can conclude that this shift is related to the activation of some right hemispheric linguistic mechanisms.