[Study of brain asymmetry with neurologically normal subjects: visual procedures].

Objectives: We present a revision of the technique of visual lateralization of stimuli as one approach to the study of brain asymmetry with regard to language. At the same time, we present a summary of the research carried out by our group using these techniques, reflecting not only the main results but also the most relevant methodological aspects.

Development: Brain asymmetry is a basic characteristic of the organization of the nervous system. In most of the principal psychological processes there exists a greater or lesser degree of hemispheric differentiation. Among these, language is possibly one of the processes most noticeably lateralized. One of the main approaches in this field is the study of neurologically normal subjects using techniques of visual lateralization of stimuli. Appropriate use of this technique requires a knowledge of the basic principles involved and of the methodological requirement, as well as the different types of tasks and stimuli, which can be adapted to these requirements.

Conclusions: The technique of lateralization of visual stimuli has a long tradition as a procedure for the study of cerebral asymmetry for language and is within the possibilities of most laboratories. However, ensuring correct lateralization requires rigorous controls and this has to be taken into consideration in the selection and adaptation of the experimental paradigm to be used. Several of these paradigms are used in our research and our results provide evidence of the relative character of cerebral asymmetry and of the participation of the right hemisphere in lexico-semantic processing.