[The physiological criteria for the ability of stimulus recognition].

Neural mechanisms are considered of such unconscious psychic phenomena as subliminal perception of semantic stimuli, psychological defence, unaccountable emotions. The results are given of many years studies conducted by means of conditioned, electrophysiological and psychophysiological methods. The possibility is proved of semantic analysis of perception on unconscious level and formation of association with the help of unrealized emotionally significant words. At present it is possible to describe only few neural mechanisms of consciousness and unconsciousness; however, the development of contemporary psychophysiology allows to state that the analysis of this problem from scientific positions is the most correct way to learn the nature of the brain processes which are the basis of these complicated psychic phenomena.