[photo-3d] Re: 3d vision again

["Abram Klooswyk" <abram.klooswyk@xxxxxx>]

Bob Maxey wrote Oct 10, 2000 :
(...) it would surprise me to learn, as one poster posted,
> that we do not see 3D from the beginning. I think we do. 
> Again, is there some information out there about this subject?

When you want information from the internet, and are not afraid
of some unusual terms, try the Nat Library of Medicine (USA) at:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi
and enter a combination of terms choosen from binocular, infants, 
stereopsis, review, amblyopia, kitten, cortex, to find abstracts 
of dozens of papers, and even more when you hit "Related Articles".

An interesting abstract is:
Eye 1996;10 ( Pt 2):182-188 "Binocularity in infancy" 
by O. Braddick from London
>>A variety of behavioural and electrophysiological studies agree 
that the onset of functional binocular interaction in human visual 
cortex normally occurs between 10 and 16 weeks of age.
Measures of sensitivity to binocular correlation and to disparity 
agree closely, and behavioural and visual evoked potential measures 
on the same infant show onset of binocularity within about a 2 week 
range. Beyond the initial onset, the maximum disparity to which 
infants are sensitive increases steadily and stereoacuity is found to 
increase very rapidly. The initial development of binocularity does 
not appear to be a consequence of improving alignment of the eyes and 
occurs even in the presence of strabismus. However, the connections 
subserving binocularity are plastic in early childhood; they can be 
disrupted by unilateral strabismus, although in some strabismic
children who use both eyes for fixation, they can adapt to serve 
stereo function at the angle of deviation and re-adapt, albeit 
temporarily, to the surgical alignment of the eyes. 
(...) <<

Compare also:  Eye 1996;10 ( Pt 2):161-166
Binocularity in prism-reared monkeys. (Crawford ML et al.)
>>Prismatic binocular dissociation in infant monkeys mimicked a 
concomitant squint. Within 3 weeks, the numbers of binocular neurons 
in the primary visual cortex were reduced by half and did not recover 
with up to 5 years of subsequent unrestricted binocular visual 
experience. The monkeys failed to show binocular summation for
spatial 
contrast sensitivity tasks and were unable to utilise horizontal 
binocular disparities in random-dot stereograms - two indices of
stereoblindness.<<

Abram Klooswyk