Laterality effects in normal subjects: evidence for interhemispheric interactions

In this review we describe three methods of research that have been used to study relationships between the cerebral hemispheres in normal human subjects. We briefly mention reaction-time studies, which have been used to measure interhemispheric transmission time; more pertinent to laterality effects, however, are lateralized visual field studies, in which stimuli can be presented either unilaterally or to both visual fields simultaneously, and dichotic listening studies, wherein different stimuli are presented to the two ears simultaneously. Recent examples from the literature of experiments employing these techniques are discussed as they pertain to an understanding of interhemispheric interaction. Some suggestions are offered concerning appropriate procedures for studying interhemispheric interactions in normal human subjects.