This has nothing to do with blind spot. The blind spot is only a thing if you close one eye. Furthermore you only have one blind spot so it would only hide one dot and it would only work at a certain distance from your eye to the screen.
The real reason here is just that the dots blend in with the grey lines when you don’t focus on them.
Brain interpolating the parts of the image missing due to blood vessels, etc over the retina I think
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This has nothing to do with blind spot. The blind spot is only a thing if you close one eye. Furthermore you only have one blind spot so it would only hide one dot and it would only work at a certain distance from your eye to the screen.
The real reason here is just that the dots blend in with the grey lines when you don’t focus on them.
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