Yes, mammalian eyes have a blind spot ... and? That is, what of it?
Physiologically it exists, there is no question of that. But has anyone on
this list ever noticed that such a thing was a characteristic of their
visual system before being told about it? And, having been told of it,
isn't the usual response to do the "move the tip of the pencil around in
the visual field until it disappears" trick, or some equivalent, to see
that it really is there?
I'd say that having to engage in an exercise like that just to find the
spot demonstrates that its value as a *functional* deficiency is somewhat
slim.
--Paul DuBoisdubois@snake.netHome Page: http://www.primate.wisc.edu/people/duboisSoftware: http://www.primate.wisc.edu/software