Cross-modal synchrony between music and visual motion modulates vection, urge to move, and comfort in VR.

Sensorimotor entrainment, the spontaneous alignment of movement with external rhythms, plays a key role in how we experience music and motion. In this study, we introduce a novel method combining musical stimuli, vection, and visually induced motion sickness (VIMS) in virtual reality (VR) to investigate how cross-modal rhythmic stimulation shapes self-motion perception and comfort. In a within-subjects design with 30 participants, we manipulated auditory conditions (Music versus Silence) and VR conditions (Realistic, Static, Isochronous, and Non-isochronous) during eight-second trials. Participants rated their urge to move, perceived self-motion, and comfort. Additionally, head motion data were analyzed for movement quantity, variability, spectral power, and intertrial phase coherence at the musical beat frequency. Results showed that music significantly increased the urge to move, particularly when paired with rhythmic visual motion. Both Isochronous and Non-isochronous visual motion reliably induced vection with no additional effect of musical beat alignment on illusion strength. Crucially, music reduced discomfort induced by rhythmic visual motion by over 20%, an effect that may have been further amplified by cross-modal synchrony. By leveraging sensorimotor entrainment elicited by music and rhythmic visual motion, this study provides new insights into how cross-modal rhythms shape perceptual and affective responses. By highlighting the potential of music to enhance engagement and reduce motion sickness, our findings pave the way for more immersive, comfortable, and musically enriched virtual experiences.