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Great Optical Illusions (Was: Why color cannot just be wavelength).
Posted: 03 July 2009 10:31 AM   [ Ignore ]   [ # 16 ]
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A little aside:  During the 2nd World War the military used red-green color insensitive soldiers to detect camouflaged installations in jungle areas.  Although everything looked like the same green to the average person, the paint pigments used to duplicate the foliage color had underlying differences which were easily seen by the color insensitive guys.

Occam

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Posted: 03 July 2009 10:39 AM   [ Ignore ]   [ # 17 ]
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Occam - 03 July 2009 10:31 AM

A little aside:  During the 2nd World War the military used red-green color insensitive soldiers to detect camouflaged installations in jungle areas.  Although everything looked like the same green to the average person, the paint pigments used to duplicate the foliage color had underlying differences which were easily seen by the color insensitive guys.

Occam

Yes, I read that when I was writing a college paper on color blindness. (See..you ARE all knowing!  smile )

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Posted: 03 July 2009 03:35 PM   [ Ignore ]   [ # 18 ]
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No, just an ancient fud with a good memory. smile

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Posted: 06 July 2009 11:49 AM   [ Ignore ]   [ # 19 ]
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Doesn’t color blind mean that a person is missing
all of the cone cells of a particular color, an
all‐or‐nothing situation?  Or do people have a few red,
green, and blue cone cells but not an entire retina full
of them?  I guess I’ve got a working set of cones, I found
the test easy enough.

But really, we are all quite blind to the electromagnetic
spectrum.  Look at that puny little band of visible light,
almost not there really, hardly worth mentioning.  Just enough
so that we apes can tell the difference between the young
tender tasty easy‐to‐digest red/yellow leaves and the
over‐ripened green leaves, on the Serengeti, from what I hear.

EMSpec.gif

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Posted: 06 July 2009 09:57 PM   [ Ignore ]   [ # 20 ]
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I agree that Cromagnans could only see a puny bit of the electro-magnetic spectrum, but we’ve done an amazing job.  While we don’t have the sense organs to see the rest of the spectrum directly, we’ve managed to “see” the whole thing from the longest radio waves to cosmic rays through technology.

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Posted: 07 July 2009 09:20 AM   [ Ignore ]   [ # 21 ]
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Occam - 06 July 2009 09:57 PM

While we don’t have the sense organs to see the rest of the spectrum directly, we’ve managed to “see” the whole thing from the longest radio waves to cosmic rays through technology.

Well, I like electronics.  I am dedicated to such technologies,
myself.  I enjoy how very fashionable and stylish the electronics
have become now-a-days, with the slim flip-phones that so many
wear on their bodies everyday, and the slim televisions and
notebook computers that they proudly show-off.  I’m happy to see
how popular electronics have become.  grin

Don’t worry about our limitations Occam, there will always be some
limitation that we have to deal with.  We are born imperfect,
will always be imperfect, and those are the people who I like!
Who would want to be friends with a perfect god, imagine all the
criticisms, and they’ll just zap you when they get angry at you!
Our limits just supply us with some good puzzles to solve!
You don’t want to get bored, do you people?

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Posted: 10 July 2009 04:10 PM   [ Ignore ]   [ # 22 ]
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Have you seen this one?  It isn’t really an optical illusion, I guess that it is more of a language illusion.  We can read scrambled words reasonably easily with all but the first and last few letters scrambled.  The Guardian UK article sounds critical, but I had an easy time reading the paragraph, except for two or three words.  cool smile

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Posted: 10 July 2009 06:03 PM   [ Ignore ]   [ # 23 ]
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jump_in_the_pit - 10 July 2009 04:10 PM

Have you seen this one?  It isn’t really an optical illusion, I guess that it is more of a language illusion.  We can read scrambled words reasonably easily with all but the first and last few letters scrambled.  The Guardian UK article sounds critical, but I had an easy time reading the paragraph, except for two or three words.  cool smile

Yes—this is a really cool problem; shows that the visual system does a lot of subconscious processing.

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Posted: 12 July 2009 11:37 AM   [ Ignore ]   [ # 24 ]
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Good point Doug.  Maybe the scrambled words are not a language illusion and are a visual illusion.  I really don’t know. 

But your thought leads me to a larger idea.  With your idea in mind, then the eyes play a much smaller role in vision than we normally give them credit for, as the primary and sole vision organ that we have.  With your idea in mind maybe it is not even the dominant vision organ, but only secondary.  If eyes are secondary, then are people with injured eyes really blind?  I mean if someone breaks their finger on their writing hand, would you now call them illiterate, or instead would you regard them as just an ordinary injured person and in need of some healing?  Maybe healing the eyes of the people with most of their vision system working can be viewed in the future as healing an injured person who was never blind and has always been an ordinary person, not a different category of person.

That was just a passing thought.

[ Edited: 12 July 2009 11:39 AM by jump_in_the_pit ]
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Posted: 12 July 2009 12:47 PM   [ Ignore ]   [ # 25 ]
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jump_in_the_pit - 12 July 2009 11:37 AM

Good point Doug.  Maybe the scrambled words are not a language illusion and are a visual illusion.  I really don’t know. 

But your thought leads me to a larger idea.  With your idea in mind, then the eyes play a much smaller role in vision than we normally give them credit for, as the primary and sole vision organ that we have.  With your idea in mind maybe it is not even the dominant vision organ, but only secondary.  If eyes are secondary, then are people with injured eyes really blind?  I mean if someone breaks their finger on their writing hand, would you now call them illiterate, or instead would you regard them as just an ordinary injured person and in need of some healing?  Maybe healing the eyes of the people with most of their vision system working can be viewed in the future as healing an injured person who was never blind and has always been an ordinary person, not a different category of person.

That was just a passing thought.

Well, on a related issue is the very odd phenomenon of blindsight, where people who claim to have no visual sense data of any kind can nonetheless perform significantly better than random on tasks that involve visual information.

E.g., the person says he is completely blind. You put numbers up on a screen before him and ask him what the numbers are. The person says that the process is idiotic because they can’t see, but you just tell them to guess. They do significantly better than chance, signifying that visual information is getting through the system even though it happens beneath the level of conscious awareness.

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Posted: 17 August 2009 08:14 AM   [ Ignore ]   [ # 26 ]
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Another neat optical illusion—four concentric circles that REALLY don’t look it ...

3qiYJ.png

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Posted: 17 August 2009 08:49 AM   [ Ignore ]   [ # 27 ]
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Occam - 03 July 2009 10:31 AM

A little aside:  During the 2nd World War the military used red-green color insensitive soldiers to detect camouflaged installations in jungle areas.  Although everything looked like the same green to the average person, the paint pigments used to duplicate the foliage color had underlying differences which were easily seen by the color insensitive guys.

Occam

I had never heard about this. Very interesting. Any idea of what the explanation is, or where I could find an explanation?

dougsmith - 17 August 2009 08:14 AM

Another neat optical illusion—four concentric circles that REALLY don’t look it ...

Make it stop, make it stop!

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Posted: 17 August 2009 11:40 AM   [ Ignore ]   [ # 28 ]
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Quoting Kritikos:

Any idea of what the explanation is,

  Assume a jungle area.  The military clears an area, erects poles and drapes fabric over them to make a large tent.  The fabric is painted to match the colors and textures of the jungle one would see from the air.  When reconnaissance planes fly over they see nothing unusual. However, they take color photos.  A red-green color blind soldier immediately recognizes the camouflageed location. 

Reason:  The pigments used to match the colors of the chlorophyll in the leaves and the gray of the shadows appear correct to the standard person.  However, those pigments absorb and radiate a different spectrum from the natural.  For example, a orange pigment and a blue can be mixed to make a decent olive drab plant like color, but the color blind would see it as gray.  The person would easily see the outline of the camp where the camouflage and the natural colors meet. 

You can probably get a better and more complete explanation if you google or Wikipedia “metamerism”.

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Posted: 17 August 2009 12:02 PM   [ Ignore ]   [ # 29 ]
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Occam - 17 August 2009 11:40 AM

Assume a jungle area.  The military clears an area, erects poles and drapes fabric over them to make a large tent.  The fabric is painted to match the colors and textures of the jungle one would see from the air.  When reconnaissance planes fly over they see nothing unusual. However, they take color photos.  A red-green color blind soldier immediately recognizes the camouflageed location. 

Reason:  The pigments used to match the colors of the chlorophyll in the leaves and the gray of the shadows appear correct to the standard person.  However, those pigments absorb and radiate a different spectrum from the natural.  For example, a orange pigment and a blue can be mixed to make a decent olive drab plant like color, but the color blind would see it as gray.  The person would easily see the outline of the camp where the camouflage and the natural colors meet. 

You can probably get a better and more complete explanation if you google or Wikipedia “metamerism”.

Occam

Thanks. As I was reading your second paragraph, before I reached the third, I thought: “Ah! Metamers!” I have previously read about the phenomenon. I just didn’t know how it might enter into the explanation of this case.

“Wikipedia” is now a verb too? Oh dear.

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Posted: 17 August 2009 05:36 PM   [ Ignore ]   [ # 30 ]
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I’ve given up on linguistic purity, so I figure if the Internet has verbalized (now that’s a nice way of messing up a perfectly good word) many nouns I may as well join the party.  LOL

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