The Effect of Visual Experience on the Development of Multisensory and Bodily Perception

Vision is believed to calibrate space perception in the other senses. Expanding on this idea, the MYSpace project hypothesizes that blind children lack the necessary tools to develop a coherent, multisensory representation of their body in space. This thesis investigates the role of vision in the development of multisensory spatial perception and body representation. First, I examined how audio-haptic signals influence perceived hand position in children with different visual experiences using an audio-tactile version of the somatic rubber hand illusion. Sighted children showed a clear influence of haptic input on proprioception, shifting their perceived hand position toward a dummy hand after synchronous brushing. In contrast, blind children reported the sensation of brushing their own hand but did not adjust their perceived hand position, indicating that their hand position is computed independently of audio-haptic signals. Next, I investigated how somatotopic convergence of audio-tactile stimuli affects the tendency to bind stimuli across the lifespan in time in blind and sighted individuals. In a temporal order judgment task, sighted individuals showed decreased temporal order acuity when sound and touch occurred on the same hand, as if spatial convergence blurred time, with children showing a lower sensitivity in general. Instead, blind children performed comparably to adults, and spatial proximity had no impact on time perception in this population. These findings suggest that blind individuals across the lifespan rely on independent sensory computations, whereas sighted individuals learn to use spatial coherence to recalibrate their perception. We further supported this idea by showing that in sighted people hands proximity strengthens the crossed hands deficit – meaning audio-tactile binding in space increased with close crossed hands. Finally, to make way for fMRI testing of acceptable durations for children and clinical populations, I contributed to validating a neuroimaging technique that improves signal-to-noise ratio. This will provide a way to image the plastic changes underpinning the distinct mechanisms of spatial representation depending on visual experience.