Filling-in of the Blindspot is Multisensory
Ailene Chan, Noelle R. B. Stiles, Carmel A. Levitan, and 2 more authors
bioRxiv, 2024
The blind spot is an area on the retina that lacks photoreceptors, thus no visual information is encoded. Yet, we can maintain the sense of a seamless visual field owing to perceptual filling-in. Traditionally viewed as a surface interpolation mechanism, filling-in has been studied predominantly under unimodal conditions. However, there are limits to this process; the brain cannot always reconstruct all surfaces. Multisensory processing may bolster the process of perceptual filling-in to occur even with complex and dynamic perceptual stimuli. In this study, we employed the Audiovisual (AV) Rabbit Illusion to investigate how auditory stimuli influence visual filling-in at the blind spot. Our findings confirmed that auditory cues can induce the perception of an illusory flash within the blind spot, indicating that the brain leverages multimodal information to enrich visual scenes. This suggests that perceptual filling-in is not merely unimodal surface interpolation but a cross-modally integrated spatial representation and therefore more similar to other visual field locations than previously hypothesized. Furthermore, for blind spot filling-in to occur, visual stimuli do not need to be spatially contiguous, they simply need to be crossmodally associated (or grouped), which supports a higher-level sensory processing in filling-in than previously understood.Competing Interest StatementThe authors have declared no competing interest.