Lateralization of visual-spatial perception in man in conditions of verbal reinforcement

Studies were carried out on the effects of positive and negative verbal reinforcement on the mental ability of normal subjects and patients with chronic alcoholism to construct standard geometrical shapes from two fragments presented tachystoscopically. Negative verbal reinforcement in healthy subjects produced reductions in the latent period and increases in the amplitude of evoked N200-P300 potentials, particularly in the right parietal lobe and the vertex. These changes were not observed in patients, and patients lesser ability to carry out visual-spatial tasks could be explained by the general reduction in evoked brain potentials and the disappearance of interhemisphere functional asymmetry, which plays an important role in visual-perceptive activity in man.