It is considered that sensitivity of cortical perceptive mechanisms changes simultaneously with alternation of alpha-rhythm phases and it affects visual recognition accuracy. To verify this statement we detected alternation of alpha-wave phases online for sending stimuli in the middle of increase-phase or in the middle of decrease phase with high precision. 15 healthy volunteers (5 male and 10 female) were observed. They also took tests to measure anxiety, extraversion and neurotism levels. Visual area O2 with maximum amplitude of alpha rhythm was used to control the stimulation. We compared reproduction (by hand drawing) after presenting sample lines in different alpha-wave phases, successfulness during copying of the samples of different lengths was also compared. Most volunteers (14 out of 15) reproduced reduced lines in comparison with samples after stimulation bound to either of two alpha-wave phases. This effect is less prominent during decrease phase (positivation), i.e. lines are drawn longer and match the sample better, than during the increase phase (especially for long-sized samples). This impact of different conditions on task performance is less manifested in volunteers with low psychoemotional stability.