This is slightly off-topic, but...
 
In the discussion of ferret vision, someone asked how it would be possible
to *know* what a ferret saw, and stated that humans of different cultures
see colors very differently.  (Sorry, I forgot who it was that posted).
 
Second point first - this is actually incorrect.  This proposal has been
around for awhile, but was refuted a few decades ago by Eleanor Rosch.  It
is true that different cultures have names for different numbers of colors,
and some cultures only have names for light and dark (and everything else is
referred to by saying something like "It's the same color as an
**whatever**").  However, this does *not* mean that they see colors
differently.  In fact, humans from every culture that has ever been tested
all see colors the same way - even if a culture has no term for "red",
members of that culture still can pick out the best red, and its the same
tint as we would choose.  Any introductory text in perception or cognitive
psychology should refute the old rumor that "primitive" cultures see fewer
colors (and yes, the original notion was tied in with notions of primitive
culture vs.  European culture.  For what its worth, Russian has one more
color term than English - but I doubt many of us feel particularly bereft,
or feel that we're missing colors others can see....)
 
As to whether ferrets see color - the original posts were asking whether
they could distinguish things that differed only in color.  They weren't
asking whether ferrets had some subjective impression that was parallel to
our perception of color - you're right that we can't know exactly what it
feels like to be a ferret.  But I don't think that we have to know that in
order to answer the question, "Do ferrets distinguish colors." As to how you
answer it - the easiest way is simply to test whether they can tell the
difference between two items that differ only in color.  A second way is
based on what is known about the ferrets' optical system.  This involves
testing the responses of individual neural cells to determine their response
patterns.  However, most of us probably feel that the question isn't one
that is important enough to be worth examining in this manner.  Does it
really matter whether ferrets see color?  Differences in color are really
just our way of perceiving differences in the wavelengths of reflected
light.  But there are still differences that *we* don't see - do any of us
miss them?  Why should it be any different for the ferret?
 
Sorry for the philosophical ramblings.  (and I hope none of this is taken as
attacking any of the previous posts, as it definately was not meant so.)
 
-rochelle
(and Shadow, Fezzik, Falstaff, Butter, and Pretty Boy Floyd, who feel sorry
for us poor humans who can't distinguish each other by smell, and for the
world of brialliant scents that we can't appreciate)
[Posted in FML issue 1452]