Thanks for the welcome. Well, there's obviously no flies on you people - you've managed to guess what I was thinking before I told you myself. The suspicion that the image formed on the retina when viewing underwater might not be inverted/the same size was actually what led me to study image formation in the eye further. Anyway, you're telling me that the image is
not inverted, and is the same size. Fair enough, I'll have to go away and think about your explanation of what's going on, but, in the mean time, here's
my take on what's going on.
From discussing this with other people, I've gathered that the difficulty people have in accepting that the image formed on the retina is actually significantly different (
if it is different, and it seems quite likely to me that it
is - but I'm not disregarding your explanation Pete) is due to the fact that: when they look at objects underwater, they see them the same way - same size & same orientation - albeit unfocused. One can readily verify this to themselves by simply submerging their eyes in a basin of water and looking at any sort of object inside the basin.
I'm going to stick my neck out here, and say something terribly cheeky - quite
CRAZY infact. This line of reasoning - if the image formed on the retina is upright/a different size, we should actually see it inverted/a different size, as our brain automatically inverts all images formed on the retina - lies on the assumption that the 'act of seeing' actually takes place
inside the brain.
I propose that it can actually take place outside the brain;
at some stage before light from an image reaches the retina to be more specific.
I also propose that visual perception occurs when the superposition of states of the quantum entities being observed - photons - collapses; the cause of this collapse being (after the initial measurement by the molecules of retinal in the photoreceptors) the registration of the visual information in V1 (striate cortex) and beyond - V2, V3 etc.
This latter, rather wild, statement deserves further elaboration. Ok. There are two relevant points that I would like to make. The first is that, the photons in our environment, until we open our eyes and
look at them (or until some other process that qualifies as a
measurement is carried out on them), exist in a superposition of states. I don't see how one can avoid this conclusion. The second is that, in my opinion, a
measurement is exactly what occurs when a photon is absorbed by a molecule of retinal in the photoreceptors. My reason for saying this is that absorption of the photon causes a
conformational change in retinal - if this doesn't qualify as a measurement I don't know what does. And if you feel that this isn't enough for collapse of the superposition of states of the photon, then I hope you will concur with my opinion that registration of the photon's existence
in the mind of a conscious observer does, and this is exactly what happens when the visual information collected at the retina is registered in the visual cortices.
Now it is
my turn to anticipate people's thoughts. 'But what about dreaming?' you might ask. The images/movies we see while dreaming certainly would seem to contradict my hypothesis on first analysis - after all, dreaming surely takes place
inside the brain - but I personally, after giving it
further analysis, don't think that this is necessarily the case. Let me explain. I have just proposed that the existence of 'photons' are a prerequisite for visual perception to take place, yet I know of no mechanism inside the brain which can create photons, at least not in the extremely organised fashion which would be necessary for what we see while dreaming. So I make a further proposal, which is this: just as the retinal molecules in photoreceptors at the back of our eye have the ability to
absorb photons, they also have the ability to
emit/
create photons. In fact, it seems to me that: just as isomerization of retinal from 11-
cis-retinal to all-
trans-retinal corresponds to the
absorption of a photon, changing back from all-
trans-retinol to 11-
cis-retinol - which is a necessary step for rhodopsin regeneration - surely corresponds to the
emission of a photon. Big deal you might say; this proves nothing; because, although information can travel from retina to cortex, information can't travel the other direction; therefore no instructions can be transferred to the retina to cause the 'highly-organised photon-emission' needed for dreaming. Again, I suggest that this is not necessarily true. Information
can and
does reach the retina from inside the brain. What are referred to as 'centrifugal fibers' have been traced as far as the
inner nuclear layer (layer directly beside photoreceptor cells, in which molecules of retinal are contained) in human retinas, where they disappear (note: 'disappear', not necessarily 'end'). Read
THIS for further information.
I would also propose that these principles be applied to the auditory system. It is well-known at this stage that efferent fibers synapse on the outer hair cells in the cochlear basilar membrane, and that the micromechanical properties of the basilar membrane can therefore be controlled from 'inside the brain'. I'm going to stick my neck out again, and suggest that this is what is responsible for what we 'hear' when we are dreaming. I've never actually got the chance to test these hypotheses - although I can think of some easily-performable experiments - but if anyone can refer me to experiments/research which contradicts them, please do so; it might even curb my heretical yodels, for the time being.
P.S. I'd seriously like to hear from people who are willing to engage in a rational, logical discussion of this issue - i.e. people who won't simply try to ram their opinions down my throat. I've discussed it in other forums, but only certain aspects of it, e.g. dreaming was never mentioned etc.
And Pete, I
will try to get back to you on what you've said.
P.P.S. 2inquisitive, it seems to me that, if the children of these tribes really do have superior visaul acuity underwater - which seems to be the case - then the refractive power of their lenses must be stronger than those of most people. The maximum refractive power of (normal people's) lenses during accomodation is 30-33 diopters, which isn't enough to focus objects by itself when viewing underwater. So I find that information quite interesting. I've wondered how the visual system of fish works also. As of yet haven't got a chance to study it though.
Thanks for your time guys!