Hemispace and information control by the two cerebral hemispheres: which interaction?

Two experiments employing subjects with different experience in tactile discrimination (blind and seeing subjects) were carried out to investigate the effect of the space location of stimuli on the information processing activity of the two cerebral hemispheres. An angle discrimination task that yields a right hemisphere superiority was used. In Experiment 1, seeing subjects showed a general superiority of the left hand (right hemisphere) which was more pronounced in the left hemispace with respect to the central and the right hemispace performance. In Experiment 2, blind subjects showed a significant superiority of the left hand in the central and in the left hemispace and no difference between the two hands in the right hemispace. In both experiments hemispace differences were due only to the modification of the left hand (right hemisphere) performance. These results suggest that the hemispace control by the contralateral hemisphere interacts only with the activity of the hemisphere dominant in the information processing.