Influence of the Body Schema on Multisensory Integration: Evidence from the Mirror Box Illusion

Abstract

When placing one hand on each side of a mirror and making synchronous bimanual movements, the mirror-reflected hand feels like one’s own hand that is hidden behind the mirror. We developed a novel mirror box illusion to investigate whether motoric, but not spatial, visuomotor congruence is sufficient for inducing multisensory integration, and importantly, if biomechanical constraints encoded in the body schema influence multisensory integration. Participants placed their hands in a mirror box in opposite postures (palm up, palm down), creating a conflict between visual and proprioceptive feedback for the hand behind the mirror. After synchronous bimanual hand movements in which the viewed and felt movements were motorically congruent but spatially in the opposite direction, participants felt that the hand behind the mirror rotated or completely flipped towards matching the hand reflection (illusory displacement), indicating facilitation of multisensory integration by motoric visuomotor congruence alone. Some wrist rotations are more difficult due to biomechanical constraints. We predicted that these biomechanical constraints would influence illusion effectiveness, even though the illusion does not involve actual limb movement. As predicted, illusory displacement increased as biomechanical constraints and angular disparity decreased, providing evidence that biomechanical constraints are processed in multisensory integration.

Mental imagery of whole-body motion along the sagittal-anteroposterior axis

“…The current results provide some evidence to suggest that whole-body motion on the sagittal-anteroposterior axis would be optimally weighted and processed in multi sensory integration. As such, these findings are not only consistent with recent findings provide evidence for dissociable contributions of different aspects of embodiment to multi sensory integration process 77 , 78 , but also add new insights to the existing literature by demonstrating that whole-body motion imagery can differentially contribute to the multi sensory integration process depending on the weighting of embodiment.…”

Sensory Alignment in Immersive Entertainment

“…There are also a range of magical illusions involving mirror boxes or reflective glass which alter the source of visual stimulation in ways that people cannot perceive. Experimental research with such equipment has demonstrated how some interesting perceptual illusions can be achieved by creating sensory stimulation in alignment with this wrongly attributed stimulation; for example: If a person places their hands either side of a mirror, so they see one hand reflected in the mirror in the position of the other (non-visible) hand, and then perform a repetitive motion with both hands, after some time, people will perceive the mirrored visible hand to actually be the invisible hand, in some cases even if the invisible hand is rotated compared the visible hand [31].…”

Electrophysiological Dynamics of Visual-Tactile Temporal Order Perception in Early Deaf Adults

“…Visual-tactile temporal sensitivity also distinctly influences perception of body ownership and representation. For instance, susceptibility to the rubber hand illusion [when a participant feels their own hand, hidden from view, being stroked while watching a rubber hand get stroked, they feel as if the rubber hand was their own (Botvinick and Cohen, 1998;Liu and Medina, 2017)] can be predicted from a subject's temporal sensitivity to visual-tactile asynchronies (Costantini et al, 2016). Not only is visual-tactile temporal acuity important for perceived body representation, improved development of sensory substitution devices relies on understanding the affected person's perceptual experience, specifically what affects perception of multimodal synchrony (Kristjánsson et al, 2016).…”