Visual reality: a new insight.

Here, here's an expiriment you can conduct at home with a pencil, paper, protractor, and any kind of narrow thin aiming device:

1. Go outside and using a small stand, or chair or whatever, tape a line on the groud, or mark one with chalk that it as straight as you can possibly get it, and at least 30 feet long.

2. Find an object like a tree or telephone pole, that is about 30-60 feet away from the line, somewhere near the line's center if you were to make a perpendicular.

3. Using the protractor, with it's straight edge paralell to the line on the ground, measure at what angle your sighting device points at the center of your object, when the Zero point on the protractor is directly over the left most edge of your line.

4. Go to the right-most edge of your line and mark the new angle for pointing at the center of the object from that position.

5. Now take some some grid paper and make a scale. Say one grid space equals one foot. Draw a scale model of your experiment on the paper. Start with the line being 30 grid spaces across. Then using the protractor find the angles you wrote down at each end of the line and draw lines that follow those angles until they meet.

6. Mark where they meet, and then count the number of spaces from the line to the point the two angled lines meet. Convert that to feet and that's actually how far away the object is in real life.

That's called triangulation, that's how we found out early estimates of things like the distance to the moon and other planetary bodies...and we still use it today by comparing telescope information from opposite sides of the Earth.

Your eyes perform a miniature version of this when you determine how far away other objects are.

As for the "experience" of the object, actually yes, Mercutio answered that as well, which had you bothered to do even the slightest modicum of research on the subject you would have understood that it is a gradual process of learning to match our real physical epxeriences to the informaiton we get from our senses.

An experiment done on infants shows that before six months old Infants really don't understand distance or depth at all. They will walk directly into, or over what would appear to be an open pit to any adult or child observer. (Luckily clear glass, lit invisibly, protects them.) At about 6 months they will stop attempting to cross areas which appear to offer no physical support as they begin to associate their visual perception of their surroundings with the notion of falling.

At 2 years they can be taught when there is an "invisible" shield present to stop the fall and when there isn't and to distinguish between the two.

We learn a piece at a time to associate how far away something is by touch, or by how many steps it takes us to get there. Then we start to associate those distances with visual cues. For instance we know on average trees are much taller than human beings. So a tree that appears to be the same height as a man about 6 feet away is probably much further than six feet away. And so forth.

In fact we get so good at it, we don't even have to think about it anymore, our visual processing just does it for us.

But it's not always perfect which is why we have optical illusions. Such as the fact that for not entirely understood reasons, the Full moon appears larger when it's near the horizon, even though obivously it isn't.
 
lifegazer said:
I can see that the eye/brain could fathom that some objects were closer than others, and some further than others. But how does it get an accurate picture of events? None of the replies here have answered that question.

The brain is very complex, doing many things in parallel. So I can explain to you how it determines the distance to one object or point, the brain is doing the same thing for all the other objects you see.
 
People who, for one reason or another, only one functioning eye, for example, have lousy depth perception. What depth perception they do have comes from contextual clues. Try looking at something with one eye shut and guess how far away it is. Then, try it with both eyes open.

BTW, is there a philosophical or religious purpose behind this thread, or do I need to move it to Science?
 
Okay ladies and gents... I concede to your better knowledge.
I shall now acknowledge that it might be possible to construct an accurate picture of reality, given time and the numerous methods you've all mentioned. I'm not 100% convinced, but you have given me ample evidence to suggest I could be wrong.
I shall now retract my argument here.
 
lifegazer said:
I can see that the eye/brain could fathom that some objects were closer than others, and some further than others. But how does it get an accurate picture of events? None of the replies here have answered that question.
Experience for the most part.

The closer things are, the easier it becomes to judge their distance by sight alone.

This is why its much easier to judge how you should throw a ball of paper into a trashcan at 3 meters away than at 6 meters away.

When you stand close to a globe (as the moon is in relation to the earth), the closest part of the globe is noticeably nearly to you than the farthest part. When you stand far away (as the sun in relation to the Earth), the difference between the closest and farthest parts of the globe is less significant.
 
lifegazer said:
Okay ladies and gents... I concede to your better knowledge.
I shall now acknowledge that it might be possible to construct an accurate picture of reality, given time and the numerous methods you've all mentioned. I'm not 100% convinced, but you have given me ample evidence to suggest I could be wrong.
I shall now retract my argument here.
Cool

:rub:
 
lifegazer said:
The materialists amongst you argue that photons enter the eye and that the eye sends info to the brain about these photons. The brain then transforms this data into abstract experience upon awareness, thus representing external reality.

Here's the question: How does the eye and/or brain know what distance any specific photon has traversed through space?
You can argue that a photon has a frequency and wavelength, but neither will tell you the length that photon has travelled. There may even be a large ensemble of such photons, from a single object. Yet what info is inherent within any of them that will inform the eye or brain the distance they have traversed? Given that all photons traverse space at the same speed, the answer appears to be that there is no info.

Let's conduct a thought experiment to get my point across: Imagine that you are blind. Now imagine that everyone around you has a water-pistol and is shooting water at you. Your skin might be able to tell you from what direction the water has come, but if we imagine that all incoming water has the same velocity (thus mirroring the same impact of the photons), then it appears impossible for the skin and/or brain to know what distance that water has traversed.
Hence, it would be impossible for the brain to create a 4-dimensional abstract representation of its external reality.

... Similarly, the same case applies for incoming photons. There is no way an incoming photon can impart the distance it has traversed to the eye/brain.
I suggest that this is evidence to prove that abstract awareness is not dependent upon an external reality.

What you've said is correct. This is why we need both visual AND tactile sensations to build up a map of the world. I do however think that considerations such as yours strongly suggest that our visual and tactile sensations are heterogenous. This would mean therefore, for example, that a blind person from birth, but who suddenly could be made to see for the very first time, would not be able to tell a cube and sphere from the visual appearance of these objects alone.

Such considerations might be taken to be suggestive that there is no mind-independent reality.
 
lifegazer said:
Okay ladies and gents... I concede to your better knowledge.
I shall now acknowledge that it might be possible to construct an accurate picture of reality, given time and the numerous methods you've all mentioned. I'm not 100% convinced, but you have given me ample evidence to suggest I could be wrong.
I shall now retract my argument here.
Wow. I am truely impressed. Our little lifegazer is growing up and becoming open minded.

:clap:
 
Re: Re: Visual reality: a new insight.

Interesting Ian said:
This would mean therefore, for example, that a blind person from birth, but who suddenly could be made to see for the very first time, would not be able to tell a cube and sphere from the visual appearance of these objects alone.
That's an interesting idea. I wonder if there have been any studies to that effect...
 
Re: Re: Visual reality: a new insight.

RussDill said:
whoa whoa whoa...back up a bit. You are assuming here that depth perception has *anything* to do with individual photons, which it doesn't. Determining how far away something is is based off a number of visual cues, all of which can be fooled.

First and formost, is stereoscopic vision. Most mammilian preditors have two eyes in the front of their face to facilitate stereoscopic vision. With stereoscopic vision, you can determine how far away something is. Simply aim both eyes at the object, and when the two images line up, you can take the angle the eyes are at, and the distance the eyes are apart, and calculate the distance. You can also calculate the distance of things that don't line up based on how far off they are from lining up. You don't have to pull out the trig book though, as a baby, your brain learned how to do all this stuff on its own.

Next would be related to stereoscopic vision, and that would be how far something moves in relation to other things when we move. This method is better when there are a great number of objects, when the objects are far away, or when you only have one eye.

After that, would be blur. If something is blurry while you are staring at things far away, it is probably up close, and vice versa.

Next would be atmospheric effects. Because our sky isn't excactly clear (more so on some days or another). You can determine by examining hue, tint, etc, how far away something is. This one really fools people when looking at pictures of the moon, because a mountain can be hundreds of miles away, and yet, because there is no atmospheric effect, we assume it is much closer.

Also, there is relative size. If we except something to be a particular size, we can use that size to determine how far away something is based on how small it apears.

Don't forget the simple effect of things being further away being partially obscured by things that are closer.

Also, we may go off other sensory cues, such as sound.

I'm sure I'm missing a few, but this should get you started.
[/B]

No, all this is irrelevant. We learn how far away something is through our tactile sensations.
 
Re: Re: Re: Visual reality: a new insight.

Interesting Ian said:


No, all this is irrelevant. We learn how far away something is through our tactile sensations.

The list was how we tell how far something is away on a day to day basis. Not how we learn to pick up these cues.
 
Mercutio said:
Oh...to add to the wonderful mentions of parallax, stereopsis, linear perspective, haze, interposition, texture gradient, accomodation and convergence, one final aspect of depth perception must be mentioned:

Which are all irrelevant.

It is learned. For us to have a functional grasp of how far away something is, we must have experience with that distance, not just with our visual picture of it. Walk or run to something you have seen, throw a rock and see how far it goes...our perception of depth only gains meaning when we can combine our visual sense with feedback from the real world. [/B]

Yes! Good! But remember the real world need not be material, and indeed there are no good arguments to suppose it is.
 
Re: Re: Re: Re: Visual reality: a new insight.

RussDill said:


The list was how we tell how far something is away on a day to day basis. Not how we learn to pick up these cues.

Okie dokie. That's fine. I don't disagree then.
 
Re: Re: Re: Visual reality: a new insight.

Upchurch said:
That's an interesting idea. I wonder if there have been any studies to that effect...
I know there have been studies with kittens raised in boxes with either vertical or horizontal lines on the walls. When placed in the real world, these cats would just walk around running into things because they could only distinguish either the vertical or horizontal but not both.
 
Re: Re: Visual reality: a new insight.

Interesting Ian said:
What you've said is correct. This is why we need both visual AND tactile sensations to build up a map of the world. I do however think that considerations such as yours strongly suggest that our visual and tactile sensations are heterogenous. This would mean therefore, for example, that a blind person from birth, but who suddenly could be made to see for the very first time, would not be able to tell a cube and sphere from the visual appearance of these objects alone.

Such considerations might be taken to be suggestive that there is no mind-independent reality.
You are quite correct.

In fact, what you have described is exactly correct. The Visual Cortex is undeveloped at birth, while you are growing up, the Visual Cortex is making and breaking connections between other neurons. Neurons begin to grow thicker and longer axons and dendrites. However, if you are blind at birth, the Visual Cortex never developes. Therefore if you suddenly do regain your sight after the Visual Cortex has passed through the stage of developing, you would be quite incapable of distinguishing the difference between a sphere and a cube. (I dont believe this inability to distinguish shapes or depth was a permanent handicap.)

I read about a case (but cant find the news article) about a guy who had this same scenario occur. I believe he was getting an "eye transplant" (thank you modern medicine for allowing me to say "eye transplant"), but when the vision was restored he could not distinguish between a 3D cube and a drawing of a cube. He described both as "a box with lines coming off". His brain had not "learned" to distinguish shapes or depth.

The visual sense organs are necessary to gather information, but they dont make any sense of it. Its the job of the Visual Cortex to make sense of it.
 
Re: Re: Re: Re: Visual reality: a new insight.

RussDill said:


The list was how we tell how far something is away on a day to day basis. Not how we learn to pick up these cues.

The trouble is that this is then a non-sequitur to Lifegazer's original point isn't it? :confused:

The point being that we do not literally see at a distance. Therefore our visual sensations cannot give any evidence for an "external world".

Is this what you meant Lifegazer?
 
Re: Re: Re: Re: Re: Visual reality: a new insight.

Interesting Ian said:
The point being that we do not literally see at a distance. Therefore our visual sensations cannot give any evidence for an "external world".
What do you mean by "we do not literally see at a distance"? How don't we?
 
Re: Re: Re: Re: Re: Visual reality: a new insight.

Interesting Ian said:


The trouble is that this is then a non-sequitur to Lifegazer's original point isn't it? :confused:

The point being that we do not literally see at a distance. Therefore our visual sensations cannot give any evidence for an "external world".

Is this what you meant Lifegazer?

Wether that was his point or not, he phrased it in such a way as to be:

"We cannot get distance information on an object from our sense of sight.

:.

"Sight offers no evidence of external reality."

:.

"All my crackpot ideas are proven correct."

Which is a continuing problems with the way he presents arguments.

Obviously of the above, 1 and 3 are demonstrably incorrect.
 
Re: Re: Re: Visual reality: a new insight.

Yahweh said:

You are quite correct.

In fact, what you have described is exactly correct. The Visual Cortex is undeveloped at birth, while you are growing up, the Visual Cortex is making and breaking connections between other neurons. Neurons begin to grow thicker and longer axons and dendrites. However, if you are blind at birth, the Visual Cortex never developes. Therefore if you suddenly do regain your sight after the Visual Cortex has passed through the stage of developing, you would be quite incapable of distinguishing the difference between a sphere and a cube.

I read about a case (but cant find the news article) about a guy who had this same scenario occur. I believe he was getting an "eye transplant" (thank you modern medicine for allowing me to say "eye transplant"), but when the vision was restored he could not distinguish between a 3D cube and a drawing of a cube. He described both as "a box with lines coming off". His brain had not "learned" to distinguish shapes or depth.

The visual sense organs are necessary to gather information, but they dont make any sense of it. Its the job of the Visual Cortex to make sense of it.

No no, it's more of a mental problem rather than a brain problem. You see we build up the hypothesis of a 3 D world from primarily our visual and tactile senses. Our vision can be absolutely perfect, but if we were blind from birth before acquiring this vision, then although we have perfect vision, we would not be able to see.

Why is this? Well it's because we haven't built up our implicit low level theory about how the world is. All we'd see is a chaos of differing colors. You wouldn't be able to make sense of your environment.
 

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