My Bac. Sci. degree is in human behavior - and we must remember that the only link we have to "reality" is our own brain. It translates shadows and light into what we believe we see and stores what we think we know. We are pretty sure babies have no idea of what they are seeing because it is upside down and their brain has not learned to interpret the patterns on the retinas yet. The brain also tends to have a bias for what we want (i.e. want to see a UFO or a ghost strongly enough and you will believe at some time that you see one).
That is why peer reviews and second opinions are important. Sometimes another set of "eyes" sees different results.
I had a high school classmate that, 5 years after graduation 1982+/-, was absolutely and truly convinced that atomic bombs had been dropped in Africa and the Apocalypse had begun. The police and staff of the grocery store where he was stuffing products in a duffle bag to survive the upcoming crisis were less convinced. (True story. He really did flip out - but those truly out of mental kilter do not recognize it in themselves because . . . you believe what your brain relates to you).
Be careful of that.
