[extropy-chat] Eyesight and Qualia

[Damien Broderick]

>>[Mary] has discovered that light does not always consist of a mix of
>>wavelengths between 7000 and 4000 angstroms but can consist of 7000
>>exclusively.
>
>No. She already knew that. Mary knew everything possible about every
>related branch of science, then stepped into the world of color and
>learned something new.

It's the difference between a verbal or numerical description of something 
we observe and the rich experience of observing it *from the inside*, as it 
were. IIRC, David Chalmers mentions in his book that he grew up with a 
visual defect that prevented him from attaining the experience of 
stereopsis-- that is, the world looked flat to him, since his eyes did not 
coordinate in creating a stereoscopic effect. Then in early adolescence 
this defect was repaired, and he had the extraordinary experience of seeing 
the world leap into depth, an experience that almost all of us take 
absolutely for granted.

Not me, alas; I was born with a squint in my left eye that was not 
corrected for some years, and during that time my brain rewired itself to 
prevent the unpleasant experience of double images. These days, children 
get the operation in infancy and are trained by masking so that they do 
develop depth perception. They hadn't work that out when I was a kid.

So now I goes about in a world that presumably would seem shockingly 
flattened to most of you; maybe the experience can be mimicked by covering 
one eye for a day or so, but I doubt it, since you've developed complex 
algorithms I don't have for rendering the world in three dimensions. I'm 
absolutely sure that if my brain could be rewired for depth (by stem cells 
and arduous training, perhaps), the qualia -- that is, the direct 
experience -- associated simply with seeing something would astonish me, 
even though I understand the principles behind it right now.

Incidentally, I already have some idea of what it would like to eff someone 
else's qualia. Because my eyes send somewhat independent streams of 
information to my brain, while generating a sort of flatscreen overlap of 
fields of view, I sometimes notice that the colour values of what I'm 
looking at are slightly different depending on which eye I have closed. 
That can be weird -- a dullish red-brown object in my suppressed eye, vivid 
crimson in the dominant field. Presumably this is true to some extent of 
everybody, but the merged image in three dimensions averages out the colour 
values from each eye.

Damien Broderick