I was reading "An Emerging Mind" by V.Ramachandran (a brilliant book by a brilliant neuroscientist if I might say so). In that he mentions of people capable of pointing to objects even though they are blind. This is because the eye is working and sending signals to various parts of the brain and the "screen" and the "spatial arrangement centers" are different. So they still know something exists to where they are pointing but cannot "see" it. Even in this case, people should not know that they are missing out on something unless they compare with someone else. Like a person born blind cannot know that others can see. What if there was a planet full of such beings?