Early attention modulates perceptual interpretation of multisensory stimuli.

Perceptual interpretation of the same multisensory stimuli may rely upon influence of attention on multisensory integration. We tested this hypothesis by recording the brain activity using magnetoencephalography in a passing-bouncing illusion with sound. Early activation of the attention-related brain areas and subsequent involvement of the multisensory areas were associated with the bouncing percept. Early activation of the unimodal sensory areas and later involvement of the attention-related areas were associated with the passing percept. Thus, the bouncing percept occurs when early attentional deployment facilitates multisensory integration modulating visual perception. The passing percept results from hierarchical sequence of the perceptual processes: early activation of the unimodal areas and late attentional deployment. Alternation of the perceptual interpretations may depend on spontaneous fluctuation of attention.