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Author Topic: Are rod and cone cells responsible for creating colours?  (Read 5004 times)

Offline biel

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biel asked the Naked Scientists:

Do you believe that the environment we see are only dark and light? Is it that the rods and cones of the eye are responsible for giving colours?

What do you think?


 

Offline Soul Surfer

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Are rod and cone cells responsible for creating colours?
« Reply #1 on: 02/08/2008 23:44:33 »
That depends on precisely what you mean in the wording of the question which is slightly ambiguous.

The cone sensors are responsible for colour vision and in most people they come in three types which respond in broad overlapping peaks to three slightly different ranges of frequencies (colours of light)the individual cones themselves only respond to the amount of the broad band of frequencies they see and do not in any way analyse the colour but the brain interprets the differences in response from the cones of different types as a colour signal.

The rods are more sensitive to lower levels of light and respond only to a broad range of colours in the blue to green area.  that is why colour vision fails at low light levels.
 

Offline RD

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Are rod and cone cells responsible for creating colours?
« Reply #2 on: 03/08/2008 01:17:12 »
The brain does add colour to neutral areas ... http://www.uq.edu.au/nuq/jack/Colorcross1.html
Keep clicking on "blanking off the surrounds" (ignore the 404 message)   
« Last Edit: 03/08/2008 01:18:57 by RD »
 

Offline LeeE

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Are rod and cone cells responsible for creating colours?
« Reply #3 on: 03/08/2008 09:18:57 »
IIRC, the cones are concentrated around the center of the retina and the rods mainly around the periphery.  I believe that the rods are more sensitive to movement as well, which is an evolutionary development that aids spotting predators (and to a lesser degree, prey) in peripheral vision.
 

Offline lightarrow

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Are rod and cone cells responsible for creating colours?
« Reply #4 on: 03/08/2008 20:06:13 »
biel asked the Naked Scientists:

Do you believe that the environment we see are only dark and light? Is it that the rods and cones of the eye are responsible for giving colours?

What do you think?
Good question. I believe that colour it's just a perception and as such exists in our mind only.
Certainly, objects that we perceive with different colours (objectively) emits electromagnetic radiations of different frequency and this can be detected with other kinds of instruments, but this doesn't mean that the "colour" exists indipendently on our perceptions, unless you "define" as colour specific frequencies of that radiation.
« Last Edit: 03/08/2008 20:07:59 by lightarrow »
 

Offline techmind

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Are rod and cone cells responsible for creating colours?
« Reply #5 on: 03/08/2008 23:37:44 »
Do you believe that the environment we see are only dark and light? Is it that the rods and cones of the eye are responsible for giving colours?


We have rods (primarily in peripheral vision) which all have much the same wavelength sensitivity - and thus cannot distinguish colours. They are however sensitive to quite low light levels.
We have cones (primarily in the central vision - fovea) which in normally-sighted people come in three varieties, with significantly overlapping Long, Medium, and Short peak sensitivities. The brain analyses the ratio of responses from the L/M/S receptors to attribute colour.

The perception of "colour" is a property of the human visual system, how the human eye interprets a given spectral distribution of light.

More info on my web page: http://www.techmind.org/colour/


There are slight variations in colour perception from one person to another (possibly also between men and women) - but the basics are well understood and we can make scientific instruments which measure "colour" fairly accurately.
« Last Edit: 03/08/2008 23:40:50 by techmind »
 

Offline biel

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Are rod and cone cells responsible for creating colours?
« Reply #6 on: 06/08/2008 06:25:42 »
Thanks guys from answering my question. But it seems that no one have given me the accurate answer Im looking for. Thanks for clearing it out "Mr. Techmind".

Here's my idea. I have ask alot of doctors but yet still haven't got the answer im looking for. I have a thought or theory that keep on bothering me since then I had my anatomy class. I think that "regardless of the cones and rods and how our mind perceive things around us, in the world where we live, it is just merely DARK and LIGHT. Black and white if you consider." Just like what "Mr. Lightarrow" conclude. I just don't get the relation of electromagnetic frequencies resulting to color. Visual can be seen in different ways. As such when we use gadgets, instruments and other visionary objects. But, the thing that I want to conclude is, "what is the real scene of our surrounding? Is colour just a perception and as such exists in our mind only?"

The perception of "colour" is a property of the human visual system, how the human eye interprets a given spectral distribution of light. Hence, without the "Human Visual System" what does our surrounding look like? Dark and Light only?
 

Offline lightarrow

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Are rod and cone cells responsible for creating colours?
« Reply #7 on: 08/08/2008 13:12:35 »
Thanks guys from answering my question. But it seems that no one have given me the accurate answer Im looking for. Thanks for clearing it out "Mr. Techmind".

Here's my idea. I have ask alot of doctors but yet still haven't got the answer im looking for. I have a thought or theory that keep on bothering me since then I had my anatomy class. I think that "regardless of the cones and rods and how our mind perceive things around us, in the world where we live, it is just merely DARK and LIGHT. Black and white if you consider." Just like what "Mr. Lightarrow" conclude. I just don't get the relation of electromagnetic frequencies resulting to color. Visual can be seen in different ways. As such when we use gadgets, instruments and other visionary objects. But, the thing that I want to conclude is, "what is the real scene of our surrounding? Is colour just a perception and as such exists in our mind only?"
You can bet it as much as you want. An educative example is the effect of coloured shadows:
http://www.thenakedscientists.com/forum/index.php?topic=8294.0
Quote
The perception of "colour" is a property of the human visual system, how the human eye interprets a given spectral distribution of light. Hence, without the "Human Visual System" what does our surrounding look like? Dark and Light only?
Firstly we must precise the the human visual system consist of the brain too, not only of the eye; you can have all the cones and rods as you like, but it's always the brain that sees the colour; an eye alone, as well as a photographic camera or any other similar device, cannot perceive a colour, but just register a different signal according to a different frequency, just as it register different signals according to different intensities.

Your question

"Hence, without the "Human Visual System" what does our surrounding look like?"

have to be specified better: "look like" for who? For a human being? Then he must have a "Human Visual System" or he won't see anything... :)

Ok, I leave you with something to think about, which could help you to answer your questions:
assume that in a surgical operation you have the nerves from the three kinds of cones exchanged, so that the red cones are now connected with the nerves that were previously connected with the blu ones...ecc. What colour will you see the objects?
 

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Are rod and cone cells responsible for creating colours?
« Reply #7 on: 08/08/2008 13:12:35 »

 

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