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Registered Member #902
Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040
Hey everybody, I pondered this theory I came up with a little while back, and wonder if it could have any conceivable use besides potentially further understanding of the Perception of Vision in the Human Eye. Hypothesis on Visual Perception and Mental Imagery First and Foremost, this theory is only understood in context, therefore readers skimming for keywords or quotes must exceed caution as to not misunderstand this essay. Our vision is a marvel of biological science, and nature has done a very good job giving us the ability to discern between different wavelengths (therefore colors) of light. The eye is well understood in its functional properties and inner workings, and this has led to very diverse treatments for visual disabilities. However, there might be more to the processing of these mental images from the eye, once inside the brain, than current science knows. The eye can be explained either simply or with extreme complexity. In short, light strikes receptors in the back of the eye to stimulate nerve pulses. It is known that there are two main types of receptors, cones and rods. One of these detects light and dark, while the other determines color. Once the nerver pulses leave the eye, they enter the brain to form the mental image which we “see.†However, what other processes are associated with the functions of the brain in the reception of sight? The main mystery this theory focuses on is the perception of color. This is not regarding colorblindness, which is already well studied. To explain in a reasonable way: Imagine one camera sending individual red, green, and blue signals to two monitors. On one monitor, the individual color signals are paired with their respective inputs. On the other monitor, the blue signal is in the place of the red signal, and the red signal takes the place of the blue signal. The green signal is connected to its respective input. Each monitor will display a different image (which is analogous to the mental image in one's perceived mental image). However, the objects in the image are the same, and also colors remain distinct but not the same, hence how this theory differs from colorblindness. This would mean that while various people's eyes are sending the same signals to the brain, the brain's processing (in this analogy the cable management) might be able to cause a perception of a color to be different among different individuals. What one person perceives as red might be what another perceives as blue. This difference potential among individuals might not be of any remote significance.
Registered Member #1617
Joined: Fri Aug 01 2008, 07:31AM
Location: Adelaide, South Australia
Posts: 139
What one person perceives as red might be what another perceives as blue.
I have wondered almost the same thing for a long time. If two people both look at say a red object, is the 'sensation' of 'red' the same in both peoples 'mind'? Of course (assuming normal colour vision), they will both refer to the colour they are 'seeing' as red, because they have learned to associate that particular 'sensation' with the word red, but there is still the posibility that the actual sensation varies from person to person. But how could it ever be tested? It might be impossible to test without being able to 'read the mind' of the people under test, and then still how can you compare the two?
This difference potential among individuals might not be of any remote significance.
Maybe not, but then again it may be a key factor in colour blindness.
Im not entirely sure if what I am thinking is the same as what you're thinking; It's extremely difficult to put into words!
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
I'm not really sure about this but I believe I read somewhere that the receptors send the signals as impulses. Maybe the impulses are different for each color. Maybe each of the receptors has other different characteristics (forward voltage drop? ) so the brain can differentiate.
It's the same with the ear, but there are thousands, not just three, types of sound receptors and each responds to only one frequency. How does the brain know which is which?
Registered Member #902
Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040
Frosty90 wrote ...
What one person perceives as red might be what another perceives as blue.
I have wondered almost the same thing for a long time. If two people both look at say a red object, is the 'sensation' of 'red' the same in both peoples 'mind'? Of course (assuming normal colour vision), they will both refer to the colour they are 'seeing' as red, because they have learned to associate that particular 'sensation' with the word red, but there is still the posibility that the actual sensation varies from person to person. But how could it ever be tested? It might be impossible to test without being able to 'read the mind' of the people under test, and then still how can you compare the two?
This difference potential among individuals might not be of any remote significance.
Maybe not, but then again it may be a key factor in colour blindness.
Im not entirely sure if what I am thinking is the same as what you're thinking; It's extremely difficult to put into words!
Cheers, Jesse
your thoughts sound to be along the lines of what I am thinking - but there might be a way to test using something like an fMRI monitoring the brains processing to controlled stimuli
In my opinion, this difference in sensation might be caused in the actual processing of impulses from the eye in the brain, but it could very well originate at the source of the receptors
as for sound having a similar issue, I have never thought of that at all, but I can see it as perfectly reasonable
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
I would expect that, as with most things, color perception is something that our brains learn. We already know that, given enough time to re-train the brain, humans can function just fine with vision inverted by prisms -- given enough time, the brain simply perceives inverted vision as right-side-up. I wouldn't be too surprised to discover that the brain could similarly cope with an inversion of color.
Think of it as being similar to the perception of taste. While there are likely slight variations in just how sensitive taste and olfactory receptors are to certain chemicals, the actual sensory impulses regarding the taste of a particular food are probably very similar from person to person. For example, I do not like watermelon. I am likely tasting all the same components and chemicals as everyone else, but my brain puts them together in such a way that I find watermelon to be unappetizing at best. Somehow, in my brain, the taste of watermelon and the smell of fermenting sewage are closely linked. Likewise, various colors in my mind are associated with various events, objects, and sensations that I likely do not share with others.
Keep in mind that what you've proposed is a hypothesis, not a theory. You'll be much closer to a theory once your hypothesis can make a testable prediction about the way the human brain behaves. Then the collection of data can start, and you're on your way to a theory.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
The brain has four colour "channels", Red, Yellow, Green and Blue. There are further complications like some "colours" do not exist at all except in your brain. For example you can't recreate brown or the perceived colour of gold by stimulating the eye with a single mixed RGB light source because some colours are created in the brain by processing contrasts in addition to the absolute colour value.
The nature of conciousness is not even remotely understood so it is possible that the hypothesis makes little sense. If your perception of the colour space is a quantum mechanical operation based on all possible combinations of input states it might be completely irrelevant. If it is a strictly classical computational process it might still be irrelevant in the sense that different code mappings can give identical output and be computationally equivalent.
With all these unknowns I think any conclusion is far off unless some clever experiments can be constructed that give clear results.
We already know that, given enough time to re-train the brain, humans can function just fine with vision inverted by prisms -- given enough time
I have done this experiment with a picture of a face and it took only 20 minutes or so before it appeared to be the correct way round (if anyone tries this it is extremely important to remove any clues to what is up and what is down, even the tip of your finger into the field of view might ruin it). The brain has a separate processing path for faces so it is possible that it is capable of adapting to upside down faces faster than other objects.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
In other words, you could argue over the meanings of "blue" and "face" until you are blue in the face.
If yellow is a fourth colour receptor, why did we only put red, green and blue in our TVs and cameras?
I spent the last two days in a round of endless meetings with the people who sponsor our research contract. The projector (used to inflict endless powerpoint presentations) seemed a little dim and bluish, and it was hard to make out shadow detail. We thought the lamp was tired, but the next day a different projector did the same. Eventually it turned out that the wire for red in the Apple VGA adaptor thingy was completely broken and we were only seeing the green and blue channels. I realised what was wrong when I spotted a guy in a black hi-vis vest in one of the site survey photographs.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
If yellow is a fourth colour receptor, why did we only put red, green and blue in our TVs and cameras?
The eye has only 3 different colour receptors but the brain converts it into 4 channels while processing the information.
After the eye the "RGB" colours are converted to something like: R+G as brightness used for edge detection and spatial information. R+G as a colour Y R-G as colour Y-B as colour
The central part of the retina where the sharp focus is has only Red and Green receptors so any sense of sharpness and resolution we perceive for Blue is mainly derived from processing where the resolution is extracted from the Yellow channel.
Since the channels are mixed like this we can not see a greenish red since it will instead register on the yellow R+G channel. And probably why red and green colour blind people can see yellow.
As usual reality it is even more complex with several different stages of colour processing and nothing in the processing is absolute but depends on both the magnitude of other channels and spatial information.
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
I wonder to what extent this is a pointless discussiuon. After all is said and one, how can anyone know what I perceive since my perceptions only exist within my brain. On the other hand I do wonder if we all have the same " favourite colour" but some of us label it differently.
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Hypothesis on Perception of Vision, thoughts?
) so the brain can differentiate.
