Seeing and Perceiving

I found this interesting blog post citing a study about how our eyes, optic nerves, and brains actually see things which we do not perceive. Our brain filters the information that it receives from the eyes and optic nerves, so that we perceive very little of what our brain actually sees.I have been wondering about those who can see spirits... is their ability to see related to their retina's characteristics, that are different than those of us who cannot see spirits?Or is this ability related to a difference in the optic nerves or the parts of the brain that process the stimuli picked up by the retina?In other words, is seeing spirits a physical ability that can be quantified or a spiritual gift that cannot?  Or is it perhaps both?  Is there actually a difference between physical and spiritual gifts?I suspect the pineal gland has something to do with spiritual gifts, but what about physically seeing something that is there, but most of us cannot see... or at least perceive with our own eyes?I'm preparing a longer article on the lesser-known abilities of the pineal gland, to be published in a couple days.  Perhaps, as this article hints, the brains of seers processes images differently than the rest of us.