Hemispheric Specialization for the Processing of Linguistic and Non-Linguistic Stimuli in Congenitally Deaf and Hearing Adults: A Review and Contribution

Abstract

Congenitally deaf individuals, interpreters for the deaf and hearing controls viewed words, dots, American sign language signs and drawings of objects presented tachistoscopically. The stimuli were presented both bilaterally and unilaterally to the subjects. The deaf subjects showed a significant left visual field (LVF) superiority for the processing of the drawings while the nondeaf groups showed significant right visual field (RVF) advantages. Laterality differences between groups on the other tasks were nonsignificant. The deaf group also showed a significant LVF advantage in the bilateral condition across all tasks as opposed to a RVF advantage yielded by nondeaf groups. A significant LVF advantage for words and dots was found compared to the RVF advantage for signs across all subjects. The differences between deaf and nondeaf groups are discussed in terms of processing strategies and the critical period for language acquisition theory. Dans des conditions bilatérales, le groupe des sourds a montré également une supériorité significative du champ visuel gauche pour toutes les reconnaissances, par opposition à une supériorité significative du champ visuel droit pour le groupe des sujets normaux. Nous avons trouvé chez tous les sujets une supériorité du champ visuel gauche pour les mots et les points, par comparaison avec le champ visuel droit pour les signes. Nous discutons la signification des différences observées entre les groupes des sujets sourds et entendants.