One of the main theories is that there are two main parts of the
   visual system. One seems to assemble the outline very quickly.
   The outline of objects is a bit of an illusion but it's
   necessary for humans. The outlining is very quick and there's a
   very fast pattern matching that takes place. Well, it's not
   pattern MATCHING it's more like, "What is this NOT." That's why
   sometimes it narrows down to a few contradictory choices at
   once: Several possibilities have nearly equal weights. A good
   example of this is a parking lot experience. You can't find your
   car. Why? You can narrow down that it's in the parking lot in
   one of the slots. But the possibilities of WHERE it's parked
   bring up MANY overlapping possibilities at once. In short, you
   don't MATCH UP so much, as inhibit until the least unlikely
   choice remains.. and sometimes there are several less unlikely
   choices. This sounds like the same as matching up, but it's
   quite different. = [I can backup with data if I have to 'cause I
   was REALLY into this stuff about 2 years ago - still am - but
   I'd rather explain it if it doesn't make sense. Sharpens my
   knowledge when I try to explain.   = To put it shorter, our
   brains go from "one to everything to one" rather than "one to
   one" ==