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By means of backward masking, the time of perception of letter stimuli presented to the left and right visual fields, was determined in practically healthy persons who were given different doses of alcohol, and in patients with chronic alcoholism. Evoked electrical activity to the same stimuli was recorded in identical conditions. A small dose of alcohol (0.41 g/kg) increases in healthy subjects the time of perception of visual signals only if they are presented in the left visual field: a medium dose (0.82 g/kg) increases the time of stimuli perception in both halves of the visual field, but obviously more so in the left one, in patients with chronic alcoholism the time of perception is substantially longer in the left visual field. A small dose of alcohol does not affect evoked electrical cortical activity in healthy persons. Distinct regional differences are exhibited in the action of the medium dose of alcohol on the cerebral cortex of healthy persons. Evoked potential in the central area is depressed to a greater extent than in the visual and associative (Brodman field 37) zones. With chronic alcohol intoxication, evoked activity in the right hemisphere is depressed considerably more than in the left one.

In patients with remote sequalae of closed brain injuries the author examined the time of perception of letter stimula by the aid of a technique of reverse masking, the time of motor reactions to simple and letter stimula and changes of these temporary parameters under the influence of small doses of alcohol (60 ml 40 degrees alcohol). The time of perception and time of motor reactions to a simple stimula were practically identical to those in normals. The time of motor reactions to aletter stimula was higher than to a simple one and in patients significantly higher than in normals. Under the influence of alcohol the time of perception and motor reactions increase in conditions of letter distinguishing. These facts permit to consider that alcohol in such patients makes the processing of information in the CNS slower and most strongly influences the central cortical processes.

Using the backward masking method the time of perception of visual stimuli in the right and the left field of vision was examined. It was found that in patients with craniocerebral injury sequelae, as well as in healthy subjects the time of perception of literal stimuli was shorter in the left field of vision, i.e. the information entering the right hemisphere was processed more rapidly. Under the action of alcohol the asymmetry of the perception time disappeared in the patients, and became inverse in the healthy subjects, i.e. the time of perceiving letters in the left field of vision got longer than in the right field. Under the action the right hemisphere seemed to lose its advantage in the speed of the stimuli perception. It is supposed that the right hemisphere is more sensitive to alcohol.

Images of two fragments of regular geometrical figures (square, triangle etc.) have been presented to 58 healthy persons successively with intervals of 20, 80, 120 and 380 ms. The subject must compare these fragments mentally, decide whether they form the standard figure and press a button by the right or left hand according to the instruction. At presentation of both fragments in one visual field, left or right, the number of correct responses is greater when they form the figure. The greater the interstimulus intervals, the greater the number of correct responses to stimuli forming and not forming the standard figure. At presentation of fragments in different visual fields, the number of correct decisions is the same, independently from forming the standard figure. The reaction time is shorter when exposing fragments forming the figure, independently from the way of their presentation; with prolongation of interstimulus intervals the reaction time decreases in all cases. The number of correct decisions is greater and the reaction time is shorter when the stimuli are presented in different visual fields.

The influence of emotional stress was studied on different links of the structure-functional system providing perception of a stimulus and choice of an adequate to signals voluntary motor reaction. Presentation of emotionally meaningful words was shown to change significantly and nonequivalently the process of stimulus recognition and the value of reaction time. The changes were more brief in persons with inborn emotional lability and significantly longer in those after the brain injury. It was shown that emotional factors might significantly change (delay) the process of decision making.

In healthy adult subjects recognition was studied of geometrical figures presented unilaterally, and of separate letters presented unilaterally and dichoptically to the right and left visual fields. At near-threshold exposition, separate letters are better recognized in the right visual field, than in the left one, regardless of the method of presentation. There is no asymmetry in recognition of geometrical figures. In conditions of backward masking asymmetry of perception of separate letters is likewise observed, but they are better recognized in the left visual field. This suggests that the perception time of separate letters is shorter when they are addressed "directly" to the right hemisphere.

The time of perceiving literal stimuli, as well as the time of the reaction to the latter were determined in chronic alcoholics and in healthy subjects. The stimuli were offered unilaterally to the left and the right field of vision using the reverse masking method. In the healthy subjects the time of perceiving the literal stimuli was shorter when the letter was presented to the left field of vision, i. e. the information entering directly the right hemisphere was processed more rapidly. The alcoholics showed an inversion of the normal interhemispheric relations because of the impairment of right hemisphere functions, i. e. the time of perceiving the letters was longer in the left than in the right field of vision. No differences between the hemispheres as regards the time of the reaction were revealed. In the alcoholics the process of decision taking was found to be greatly slowed down.

Reaction time (RT) and the number of correct estimations of time microintervals (10 and 180 ms) between two visual stimuli were recorded in healthy subjects. It has been shown that 10 ms interval is better estimated when the stimuli are presented in the right visual field, i.e. when they are addressed directly to the left hemisphere. At the same time the number of correct estimations of 180 ms interval is greater and their RT is less when the stimuli are addressed directly to the right hemisphere. This points to different hemispheric mechanisms of time microintervals estimation. Study of the influence of different forms of verbal reinforcement on this learning has shown that after positive reinforcement (the word "good") the number of correct estimations is on average by 10% greater than after negative reinforcement (the word "error"). This may be connected with such processes as isolation and identification of erroneous reaction.

The images of two fragments of simple geometrical figures (square, triangle, etc.) were successively presented to healthy adult subjects in the left and right visual fields with the interval of 20, 80 and 380 ms; the subjects had to compare them mentally and decide whether they formed a geometrical figure. The correctness of reaction was controlled by a computer which lightened on the screen the word "correct" or "error". The number of correct decisions was significantly greater in response to the stimuli, forming a regular figure and increased with the increase of interstimuli interval. At the interval of 120 ms, when no regular figure could be formed from two fragments, the number of correct decisions was greater if the stimuli were presented in the left visual field. The reaction time did not depend on the hemisphere to which information was addressed; it was less in response to the stimuli forming a regular figure, and became shorter with the increase of the interstimuli interval.