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

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

John A. Rupkalvis wrote Oct 10, 2000:
> (...) on further reflection, I don't think that to "try it 
> out regardless" is that bad an idea.
> (...)
> This advice should apply to all of us, even for learning to 
> freeview, or view with mirrors, or any other visual activity 
> for which we are not already accustomed.

I fully agree on the freeview issue, but that is quite different
from Rogers' daughters case, which presumably is not just a
matter of being "accustomed".
Learning to freeview is advised to people with proven 
stereopsis (we assume), but unfortunately people who have 
never had binocular vision from birth on will never learn it 
at an adult age. 

Gabriel Jacob Oct 10, 2000:
>Actually, the moment you are born you don't see 3-D. 
>You don't even see 2-D very well either! Surprisingly, 
the brain is not hardwired at birth for (clear) vision.

This is indeed the case, and "hardwired" is to be token
more or less literally, for it has to do with axons
growing out off nerve cells to reach other nerve cells,
to form a network, far more complicated than the internet.

In early life ( after birth) so called binocular cells are 
formed in the brain, this are the cells responsible for 
stereo vision.
It has been demonstrated in kittens (and also in monkeys
if memory serves) that these binocular cells are not
formed when the young animals are deprived of binocular vision.
After some time the hard wiring of the visual system is over, 
and then never any binocular cell will be formed anymore,
even if both eyes individually work normal.

The visual system of cats resembles that of humans
enough to assume that the same holds for children.
Encouraging training when anatomy rules out the possibility
of success is a mistake, I believe. Especially when tests
are available which can establish if there is any chance
to be successful in trainings.

"Monocular" persons don't often miss binocular vision in
everyday life, and I would avoid any activity which would
stress that they are (somewhat) handicapped.

But again, for non-stereoviewing persons I would recommend
the "wobble" technique, when you insist on showing something
of a stereo effect.

Abram Klooswyk