[Spontaneous and visually induced illusory responses in weightlessness (results of the Austrian-Russian experiment "Optovert" performed within the framework of the program "Austromir", part I)].

There presented the results of studying the mechanisms of intersensory interactions and sensory adaptations, the dynamics of the stability of adaptive changes in the short- and long-term space missions by phenomenology of spontaneous and visually-induced illusory responses. It is shown that adaptation to microgravity even under good subjective health condition and the absence of anomalous subjective reactions was accompanied the change in the interaction of the sensory systems. For the first time there recorded the previously unknown phenomena: an inversion of vertical vection illusion (VVI) on vertical and sinusoidal optokinetic stimulation; disruption of the perception of body scheme at the instant of VVI; the change of character and the initiation of VVI asymmetry; the decrease of thresholds and the intensity increase of VVI.