Perception plays a vital role in a beings life, especially in that of a human. Many people choose to believe what they see, and believing links with knowing as it is a component of knowing. We also choose to see what we believe and therefore both statements are complimentary.
Human beings tend to believe with evidence rather than believing in something blindly. Belief is usually based on evidence and the evidence is usually linked with our senses. If we see something, we believe in it because we are able to back our assumption with evidence because we have witnessed it.
Human reality may also be based on scientific evidence because science which involves historical evidence is able to prove certain theories. Even though we may not witness it with our senses, we believe in the theories accepted by many other scientists. For example, the world trade center was demolished on September 11th, 2001.
We suddenly think, how is it possible to destroy one of the greatest and tallest buildings in the world even after the first attempt to destroy it back in 1993. Suddenly as we see it everywhere in the news and read it everywhere, we strongly believe in it rather than half believing in it because we have seen images and video clips of the incident.
Humans, according to E.F. Schumacher have the elements of matter, life, consciousness, and self awareness or intelligence. Our self awareness enables us to see things the way we do and it is accepted psychologically that we "hold fast to what we can see and experience."
Yet knowledge plays a vital role in believing along with language. Since we can read and understand as well as communicate, we can share ideas expanding our knowledge. This also ties in with the senses of hearing...