Enhanced image generation abilities in deaf signers: a right hemisphere effect.

Deaf subjects who use American Sign Language as their primary language generated visual mental images faster than hearing nonsigning subjects when stimuli were initially presented to the right hemisphere. Deaf subjects exhibited a strong right hemisphere advantage for image generation using either categorical or coordinate spatial relations representations. In contrast, hearing subjects showed evidence of left hemisphere processing for categorical spatial relations representations, and no hemispheric asymmetry for coordinate spatial relations representations. The enhanced right hemisphere image generation abilities observed in deaf singers may be linked to a stronger right hemisphere involvement in processing imageable signs and linguistically encoded spatial relations.