The nonspeech assessment of hemispheric specialization in retarded children.

A visual half-field presentation technique was used to assess hemispheric asymmetries in young, language-deficient, retarded children who had been taught a nonspeech graphic symbol system. Unlike most tachistoscopic and dichotic listening methods, the present method did not require verbal instruction or verbal responses. In addition, the subjects' explicit understanding of the need to fixate visually prior to stimulus presentation was not necessary. Meaningful graphic symbols were recognized more accurately when presented to the hemisphere associated with the dominant eye and hand. Recognition of meaningless symbols was best when they were presented to the nondominant hemisphere. There was a significant hemispheric specialization effect similar to what would be expected in older, normal subjects using traditional methods.