Expert: Dana Krempels, Ph.D. - 8/21/2008

Question
QUESTION: Sorry I don't mean to ask the same question again, but I have been told our cones and rod vary, which I remember I have told that all human share the same optical structure including rod and cones, and there is no way to find out whether we perceive the same colour or not.

-Does every human has different rod and cones?
-I thought It is impossible to test and prove whether does we have the same colour experience?
-Don't we have the same colour system in our body? since we are same species?
-Why the info I get here is different from rest of the expert?
-Is it true we have different rod and cones in our eye?

Is it being proven yet?

ANSWER: Dear Rambo,

You really are asking just about the same question again and again, and I really can't do anything but give you the same answer.  Humans all have the same basic structure of the eye and associated visual and central nervous system structures. This is not to say that we are as exactly the same as clones.  Each of us has unique DNA, and that means that any proteins or enzymes could be slightly different among humans. And *that* means that some structures can vary slightly among humans, including visual pigments.

Whether this means we perceive colors differently is impossible to say, for all the reasons I have told you several times before.

I don't know why my answers are different from answers you are getting from others, especially since I don't even know what you are being told by others.  

But I'll say it again: color is a psychophysical phenomenon.  There is every reason to suspect that the more closely related we are, the more similarly we see colors and smell smells and taste tastes, but there is *no way to test or prove this.*  There are some tests one can do to see whether two different humans can perceive different color hue changes more accurately than others, but there is no way to know exactly how the brains of those humans perceive the colors any more than it's possible to visualize another person's dreams.

Wish I could give you the answer you seek, but this is the answer I can confidently give you.

Good luck,

Dana

---------- FOLLOW-UP ----------

QUESTION: -Do human has the same perception of colour and has the same visual experience?
-Is there a reason that human evolved to see the colour the way it is?

I want ask why do human seem seem to be able to agree on following phenonenon?
-Is it true that yellow appear to be less visible than other colour on a white paper?
-Is it true that all human follow the order of spectrum colour? If I put two object together, red and orange, the other human will not see it as green and violet? as we all agree that red and ornage are "close" colour.
-Is it true that some colour appear more "obivous" than on certain colour background? Is it because of the colour properties?
-Is there really colour properties? is colour is just a perception of the mind?
-If all human follow the same colour properties and agree on the "properties of colour", do all human share the same colour system?
-Is it possible that we may perceive the same colour? same colour perception?
-There is some colour is like seem like two colour, like indigo, some people interpret it as violet, and some interpret it as purple; and there is also colour like aquamarine, some people interpret it as blue, some see it as green?
-It is true some colour, seem to "between of two colour" like yellowgreen? and some colour like very close, like yellow and green? which cause us to see the same thing in two colour perception?
-Does it prove that some colour we perceive depend on our brain interpretion? that why some people get different perception in the same colour?

-How do we define "beauty"? Why did human brain able to tell from beauty and ugly, despite two person is having the same face feature? How do human brain intepret pretty? Do you and I "see the same thing"?
-why do we agree on the perception of pretty? Do we "see the same thing"? Does pretty thing really exist?
-How do know we actually perceive the same sense of beauiful attraction from opposite sex? Is there any prove from evolution or genetic that we show that our brain actually have the same perception over beauty?

-How about size? Texture? Distance? Human look? Do we has totally different perception as each other? Mean we have different perception of this world??
-Is it possible for human to share the same visual experience? Do we have the same visual receptor?
-can I see what you see?Do we have the same vision field? Do we have the same colour system since we belong to the same species?

Some animals has the wild has evolution to certain colours like blue or green, are usually poisonous or attracting opposite sex, does those colour has meaning in them? do human interpret those colour as "dangerous"?
Do you think we see the same blue as "blue"


ANSWER: Dear Rambo,

I will code questions I have answered before as "see previous answers."  However, you do have a few questions that are different, and I'll try to answer those.

Quoting you:

-Do human has the same perception of colour and has the same visual experience?

SEE PREVIOUS ANSWERS.

-Is there a reason that human evolved to see the colour the way it is?

Very likely, yes.  Any trait an organism has can be considered:

adaptive - increases the chances of leaving offspring
maladaptive - decreases the chance of leaving offspring
neutral - does not affect the chances of leaving offspring

Organisms with adaptive traits leave a disproportionate number of offspring to the next generation, so the genetically encoded traits they have are passed on.  This was probably true of the ancestral primates that had the ability to see color:  primates who could detect a ripe, red fruit in a tree had an advantage over those who could not, so they got more food and had more babies.  Natural selection in action.

I want ask why do human seem seem to be able to agree on following phenonenon?
-Is it true that yellow appear to be less visible than other colour on a white paper?

Yes, because "yellow" (~ 550nm) has higher brightness and lower saturation than other colors in the human brain.

-Is it true that all human follow the order of spectrum colour? If I put two object together, red and orange, the other human will not see it as green and violet? as we all agree that red and ornage are "close" colour.

Yes, unless that person has a particular type of color blindness.  Some humans lack certain cone pigments, so they cannot see all the colors that a normal, trichromatic human can see.  You can read more about this here:

http://colorvisiontesting.com/

-Is it true that some colour appear more "obvious" than on certain colour background? Is it because of the colour properties?

Certain colors contrast more with particular "partner" colors than others, and this is because of the way the brain perceives them--not anything inherent in the wavelengths themselves. This almost goes under the category of SEE PREVIOUS ANSWERS.

-Is there really colour properties? is colour is just a perception of the mind?

The only "property" a color has is its wavelength and frequency.  But it becomes a "color" only when perceived by a visual system and brain.


-If all human follow the same colour properties and agree on the "properties of colour", do all human share the same colour system?

No.  Some are color blind.  Also, see previous answers.

-Is it possible that we may perceive the same colour? same colour perception?

Yes, it's possible.  But SEE PREVIOUS ANSWERS.

-There is some colour is like seem like two colour, like indigo, some people interpret it as violet, and some interpret it as purple; and there is also colour like aquamarine, some people interpret it as blue, some see it as green?

Yes.  This is because certain people are less sensitive to slight variations in hue, and cannot see as many colors as other humans.  This is hard to detect in everyday living, but can be tested in the laboratory with a spectral sensitivity test and hue discrimination test:

http://www.visualexpert.com/FAQ/Part2/cfaqPart2.html

-It is true some colour, seem to "between of two colour" like yellowgreen? and some colour like very close, like yellow and green? which cause us to see the same thing in two colour perception?

Different wavelengths excite different proportions of the red, blue, or green cone receptors in our retina, and so we are able to perceive those different proportions of excitement as different colors.

You will probably find the FAQ here very helpful and interesting:

http://www.visualexpert.com/faq.html

-Does it prove that some colour we perceive depend on our brain interpretion? that why some people get different perception in the same colour?

SEE PREVIOUS ANSWERS.

-How do we define "beauty"? Why did human brain able to tell from beauty and ugly, despite two person is having the same face feature? How do human brain intepret pretty? Do you and I "see the same thing"?

This is an interesting question.  Different cultures define beauty in different ways, but one very ancient criterion on which all cultures agree reflect basic biology:  the more symmetrical a body or face is, the more it is considered "beautiful" in all cultures.  This may be because body symmetry reflects genetic health, and so we are attracted to it because we want to pass our own genes along with this attractive, genetically healthy person of the opposite sex.

There's a very nice overview here, though the pictures have been removed:

http://hss.fullerton.edu/sociology/orleans/symmetry.txt

and here:

http://www.jyi.org/volumes/volume6/issue6/features/feng.html

-why do we agree on the perception of pretty? Do we "see the same thing"? Does pretty thing really exist?

See previous answers.

-How do know we actually perceive the same sense of beautiful attraction from opposite sex? Is there any prove from evolution or genetic that we show that our brain actually have the same perception over beauty?

Yes. Read the articles above, and you will find them interesting.

-How about size? Texture? Distance? Human look? Do we has totally different perception as each other? Mean we have different perception of this world??

SEE PREVIOUS ANSWERS.

-Is it possible for human to share the same visual experience? Do we have the same visual receptor?

Yes, we have basically the same receptors, with some slight variation.  See previous answers.  

-can I see what you see?  Do we have the same vision field? Do we have the same colour system since we belong to the same species?

SEE PREVIOUS ANSWERS.

-Some animals in the wild has evolution to certain colours like blue or green, are usually poisonous or attracting opposite sex, does those colour has meaning in them?

It has meaning to them, if they react to it.  But we cannot get inside their heads to know exactly what they perceive.

-do human interpret those colour as "dangerous"?

If a color is associated with a negative stimulus, then the human will learn that assocation.

-Do you think we see the same blue as "blue"

See previous answers.

Hope that helps.

Dana

---------- FOLLOW-UP ----------

QUESTION: -can I say it is highly possible we may perceive the same colour since we belong species?

although we cannot prove it?

Answer
Dear Rambo,

It would not be unreasonable to suspect that we perceive color the same way (and other stimuli, for similar reasons) because the genetically encoded traits that enable us to perceive color are similar in our species.  There may be individual differences, but we cannot prove this.

Dana
P.S. - After answering all these questions, don't you think I should be Volunteer of the Month?  ;)