>Pam opened my eyes (LOL!) to this new interesting abstract:
  <http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed
&dopt=Abstract&list_uids=16647737&query_hl=3&itool=pubmed_docsum>
 
> Vision Res. 2006 Apr 27; [Epub ahead of print]
> Motion perception deficits in albino ferrets (Mustela putorius furo).
> Hupfeld D, Distler C, Hoffmann KP.
> Allgemeine Zoologie & Neurobiologie, Ruhr-Universitaet Bochum,
> Universitaetsstr. 150, ND 7/31, 44780 Bochum, Germany.
>
> Albino ferrets contrary to their pigmented conspecifics show no
> optokinetic nystagmus. Therefore, in this study motion perception
> was compared between pigmented and albino ferrets (Mustela putorius
> furo) trained to discriminate between coherently moving random dot
> patterns and dynamic noise stimuli in a two-alternative forced
> choice task. Fully coherently versus incoherently moving patterns
> could be distinguished by ferrets of both phenotypes. Motion
> coherence thresholds, however, were significantly higher in
> albinos. These results indicate that albino ferrets are not motion
> blind as could be expected from their total lack of optokinetic
> reactions. However, they are severely impaired in global motion
> perception.
 
Ah!  I found a definition that could be taken up large enough in size
when seen as an HTML version of the pdf:
 
http://www.deejayvision.org/PDFs/Z&Zchapter.pdf
 
START QUOTE
"Global motion", as opposed to "local motion", is the perceived direction
of a dynamic input when that direction is the result of a combination of
many individual motion signals within the stimulus.  Although individual
local motion vectors remain visible, if not easily independently
discriminable, a single overall direction of the pattern motion -- the
global motion -- is also perceived.  It is a matter of definition whether
there is really a global percept when all local signals are identical
to each other and to the overall percept of motion.  As a general rule
one assumes that not all contributing local signals imply movement in
that same global direction when discussing motion in these terms.
Furthermore, the distinction of global motion as opposed to local motion
strongly suggests that disparate motion signals are integrated from
several locations in order to extract the overall direction.
END QUOTE
 
So, if I read this right is like seeing the over-all direction of a herd
even when there is also some independent motion going on like when young
animals are playing back and forth while the herd is also moving.
 
So (again, if I read it right) these albino ferrets would be able to pick
out that individual motion exists but would not be able to discern the
general direction of the herd, and they have some trouble discerning
overall direction with individuals, too.
 
-- Sukie (not a vet, and not speaking for any of the below in my
private posts)
Recommended health resources to help ferrets and the people who love
them:
Ferret Health List
http://www.smartgroups.com/groups/ferrethealth
FHL Archives
http://ferrethealth.org/archive/
AFIP Ferret Pathology
http://www.afip.org/ferrets/index.html
Miamiferrets
http://www.miamiferret.org/fhc/
International Ferret Congress Critical References
http://www.ferretcongress.org
[Posted in FML issue 5231]