>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]