functional “specialization” of the hemispheres of the brain of humans and animals; In the implementation of some mental functions, the left hemisphere is the leading one, while in others the right hemisphere is the leading one. It has been shown that the left hemisphere in right-handers plays a predominant role in expressive and impressional speech, in reading, writing, verbal memory and verbal thinking. The right hemisphere is the leading hemisphere for non-speech, for example, musical hearing, visual-spatial orientation, non-verbal memory, criticality. It was also shown that the left hemisphere is more focused on predicting future states, and the right hemisphere is more focused on interacting with experience and current events. The mature functions of the left and right hemispheres are represented by the following series: causal – non-causal, planning – knowing, controlling – abiding, active – receptive, intellectual – intuitive, analytical – synthetic, successive – simultaneous, concentrated – diffuse, thinking – feeling, time – space, past and future – present, verbal – figurative. In the process of individual development, the severity of interhemispheric asymmetry changes, and lateralization of brain functions occurs. At the same time, within certain limits, there is interchangeability of the cerebral hemispheres.