Stereoscopic Vision and The Hard Problem
Amazing
We've discussed the problems of cognition and consciousness here many times. The position I've been exploring treats something like consciousness as something happening in the physical world. Under the assumption that any explanation we might have for consciousness can be, and indeed from the approach I've been looking at, conscious must be grounded in physical reality. And not grounded in some mysterious property of reality invented especially to account for consciousness. The same approach can be applied to other problems of cognition, from perception of colour to moral interpretations - all of these things have to be grounded somehow in physical reality. The idea of grounding is significant here - it is a very distinct idea from reducing mental phenomenon to physical reality. For instance; is a shadow reducible to physical reality? After all, a shadow has no substance of any sort. But it's easy to see how a shadow is grounded in physical reality. It's easy to explain why the shadow is there.
There are other ways of looking at this issue of course.
David Chalmer's Hard Problem explores the matter with a different assumption.
He assumes that what we experience is fundamentally different from whatever physical process may cause them.
That is, no matter HOW we explain how the brain might cause experience; for Chalmers we haven't made any progress at all at explaining experience itself.
That's the Hard Problem - explaining experience itself.
I've never thought the Hard Problem was a real problem at all but I found it hard to express just why I didn't think it was a problem. I was reflecting on stereoscopic vision recently and had a new idea about it.
I've been fascinated by stereo vision for a long time. It's about how we perceive depth. I've made my own stereo photographs using at least 6 different techniques, where I built my own tech and viewers.
It really is a simple technology. It's based on the fact that we see with two eyes - most animals do. When you look at something in the center of your field of vision, if it's in a certain range, then your left eye inclines a bit to the right and your right eye a bit to the left. The amount of mutual inclination required to bring things at varying depths depends directly on depth. The geometry is really simple. This information is passed to the brain via muscular nerves instead of optic nerves.
So let's consider what else is happening when we look at that something in the center of our visual field. Our eyes are jumping all over the place in saccades; moving dozens of times a second all over your field of view. You have no experience of that at all - the visual field steady.
I made a stereo picture to illustrate my point.
You need to look at it right to get the depth effect. Looking at it right involves crossing your eyes in the way that causes the left half of the image be superimposed on the right.
It's not hard, and is a standard technique for viewing stereo images, but it takes a bit of practice to get it. But once you get the trick it's pretty vivid
I made the picture. I know how it's done.
Here's the point I'm trying to get at - when we perceive things as having depth and sharp edges when we know this isn't what we are looking at. A whole pile processes happen in the brain that we are entirely unaware of and the end product seems to be a SORTA knowledge. That knowledge is what the thing looks like to us. So perception isn't a representation projected on a screen. Instead it's knowing how things look.
What's going on here?
Many people have described how the neocortex seems to be composed of a vast array of interconnected pattern matchers.
The interconnection is such that when lower level pattern matchers fire their pattern of firing sets off higher level pattern matchers.
A cascade of this sort activity has top level pattern matchers that are more accurately thought of as interpreters (because that gets better at their role in our cognitive structure).
Basically the output of interpreters is meaning. We know what a various high level patterns mean. A sudden drop of water on our face makes us look for rain or a sprinkler or watergun - it has meaning as soon as we are aware of it. We know what that feeling means - we have no contact with the processes that gave us that knowledge, other than what we know because of them.
So - with stereographic vision we have a whole bunch of things happening in the brain.
The eyes are saccading around and it's muscles are reporting the movement as the retina reports the photons.
Cascades of pattern matchers extract the steady data of the saccades, and also gets informed by the information about muscle movements.
By the time the high level interpreters are firing we know that this thing is in front of the other.
We don't build that knowledge by any sort of rational process.
The pattern matchers that give us knowledge of depth work and the process whereby such processes can be created by evolution are easy to imagine.
The reason evolution would do it is that creatures that could recognize depth would have a significant reproductive advantage. One eyed frogs don't live long because all the other frogs can get flies and they can't. We have reason to hope that the detailed mechanism of how that cascades of interpreters might produce stereoscopic be actually worked out in great detail. Since after all it is found that stereoscopic vision is found in animals much simpler than people, and so it seems that our huge brains aren't needed for it. And this gives hope that perhaps even Chalmers will come to see that in all it's amazingness, human cognition is grounded in physical reality.
What do you think?
I present regular philosophy discussions in a virtual reality called Second Life.
I set a topic and people come as avatars and sit around a virtual table to discuss it.
Each week I write a short essay to set the topic.
I show a selection of them here.