The visual gaps created by the retinal blindspots are normally irrelevant since corresponding information from the other eye is available, but even during monocular viewing the gaps are filled in by the brain. Since individuals without binocular vision (e.g., amblyopia, strabismus, monocular) have more day-to-day experience with filled-in information, they might be better at recognizing it as unreliable, and therefore have less confidence in it. Alternatively, they might have more confidence in it because filling-in might work better than in normal-sighted individuals.

Here, we tested confidence in filling-in of the blindspot using grating stimuli with or without an orthogonal central portion that was smaller than the blindspot. These stimuli were shown monocularly either at the blindspot or at the corresponding location on the opposite side of the visual field. Normal-sighted and non-binocular individuals first had to judge which of two consecutive stimuli to rate (confidence task), then rate whether the chosen stimulus had a central portion or not (perception task). Overall, non-binocular individuals seemed to experience perceptual filling-in as robustly as normal-sighted individuals. However, the non-binocular individuals were more likely to trust the filled-information in their blindspot. Control experiments verified that this was not due to differences in perceived distortions between the tested locations. The results suggest a stronger reliance on filling-in mechanisms when alternative information from the other eye is not available.