There is growing interest in the effect of sound on visual motion perception. One model involves the illusion created when two identical objects moving towards each other on a two-dimensional visual display can be seen to either bounce off or stream through each other. Previous studies show that the large bias normally seen toward the streaming percept can be modulated by the presentation of an auditory event at the moment of coincidence. However, no reports to date provide sufficient evidence to (...) indicate whether the sound bounce-inducing effect is due to a perceptual binding process or merely to an explicit inference resulting from the transient auditory stimulus resembling a physical collision of two objects. In the present study, we used a novel experimental design in which a subliminal sound was presented either 150 ms before, at, or 150 ms after the moment of coincidence of two disks moving towards each other. The results showed that there was an increased perception of bouncing when the subliminal sound was presented at or 150 ms after the moment of coincidence compared to when no sound was presented. These findings provide the first empirical demonstration that activation of the human auditory system without reaching consciousness affects the perception of an ambiguous visual motion display. (shrink)

Here we question the mechanisms underlying the emergence of the feeling of control that can be modulated even when the feeling of being the author of one’s own action is intact. With a haptic robot, participants made series of vertical pointing actions on a virtual surface, which was sometimes postponed by a small temporal delay (15 or 65 ms). Subjects then evaluated their subjective feeling of control. Results showed that after temporal distortions, the hand-trajectories were adapted effectively but that the (...) feeling of control decreased significantly. This was observed even in the case of subliminal distortions for which subjects did not consciously detect the presence of a distortion. Our findings suggest that both supraliminal and subliminal temporal distortions that occur within a healthy perceptual–motor system impact the conscious experience of the feeling of control of self-initiated motor actions. (shrink)