ИСТИНА

Body ownership depends on convergent input of multimodal stimuli from visual, tactile, kinesthetic and other modalities. By manipulating of these sensory inputs we can investigate mechanisms of body ownership like it was in a "rubber hand illusion", one of somatosensory or body illusions. Dynamics of onset and fading of these illusions is an important research question. The aim of this study was to investigate the temporal dynamics of two body illusions: a static rubber hand illusion (RHI) and a moving virtual hand illusion (VHI). Thirty-three healthy subjects participated in this experiment. The comparison of two types of illusions allowed us to directly test the contribution of different modalities in body ownership and to compare two types of multisensory integration processes, tactile-visual and kinesthetic-visual integration. Two methods were used for illusions estimation: a subjective measure (ownership questionnaire), and a behavioral measure (proprioceptive drift evaluation). The general dynamics of proprioceptive drift were similar in both illusions: during the onset phase of artificial hand representation proprioceptive drift gradually increased, and during the fading phase proprioceptive drift gradually decreased. Subjective sense of ownership of an artificial hand was found in both illusions (test questions were significantly higher than control), but positive dynamics of the ownership was found in the RHI but not in the VHI. As well, subjective experience of the ownership illusion was higher towards the RHI, but not to the VHI. A kinematic analysis of the moving VHI revealed several motion features (such as jerk, smoothness and velocity), predicted illusion measures.