On Fri, 14 Jul 2006 21:50:47 GMT, Rich the Philosophizer Gave us:
The brain interprets the visual data from your eye, and even changes the way it does so on the fly. Not related to blind spots per se, but watch some vertically scrolling text for a few minutes, the move to a page of text that isn't moving... and it will appear to be scrolling!
Same thing for motor biking. Watch a gravel road pass under your feet for a while then look up at the non scrolling world, and see that your brain has changed the way it deals with the imagery. It takes a few seconds for it to revert back to full frame processing.
Even right to left scrolling (or left to right of course), such as a news or stock ticker tape scrolling on your screen can cause the effect.