Does colo(u)r exist outside the brain

[MiM]

JimC again:
"We can "fool" the brain using this. If you shine 2 rays, say from a LED sources, one of pure green and the other red, equal intensities, we experience exactly the same qualia that would be generated by a beam of pure yellow. I use this to emphasise to my students that our vision sense is very different from a scientific instrument like a spectrophotometer..."

Which neatly brings us to the next question "Does colour exist outside the human brain". The difference to the "number" discussion should be obvious, as colours are so clearly subjectively impertreted, influenced by the environment, yada, yada...

[Svartalf]

Do cameras, color copiers, printers, etc have a brain that they can faithfully reproduce what should only be a figment of the mind?

[Audley Strange]

I'd say no. Certainly electromagnetic phenomena does, but colour is merely a limited perception of such.

[Rum]

We need receptors sensitive to the correct wavelength of the electromagnetic spectrum. If we don't they are invisible, but 'waving/particling' in that wavelength anyway. Requires the brain I would suggest to apprehend the colour itself.

[MiM]

You probably all know this one.

[Svartalf]

I don't, what's the meaning of posting this?

[MiM]

What is the difference in absolute shade between square A and square B?

[JimC]

What is the difference in absolute shade between square A and square B?

None.

Much our visual perception is strongly relative. It's not there to provide a neutral, "scientific" view of external reality, but to allow us to build the most effective mental model of our surroundings that we can, all the better to find nice food and detect large predators...

On the OP, I would say that photon wavelength is an objective reality, but that colour and shade are sensations or qualia that correlate in certain ways with wavelength and intensity of light, but are themselves individual and subjective elements of the mental model generated by an individual human.

[macdoc]

It's too easy to fall into semantics here.

As with everything else colours exist "as we define them" in the real world as portions of the EM spectrum we can recognise as discrete and have agreed by convention.

There are phantom colours in our brain as well. In this case the brain is manufacturing the apparent color in the white cross point.

[JimC]

Very interesting, macdoc, how the blue-grey (to me, at least...) colours appear and disappear as your eye moves over the image...

Optical illusions of various sorts help us to deconstruct our visual processing system...

[Rum]

I suspect that much of the 'real' world we think we perceive as we go about our lives is a sort of virtual construct. We seem to live virtual realty lives in many respects..

[JimC]

I suspect that much of the 'real' world we think we perceive as we go about our lives is a sort of virtual construct. We seem to live virtual realty lives in many respects..

I agree in terms of individual human perceptions. However, I'm an old fashioned objective rationalist in the sense that I am firmly convinced that there is an objective physical reality out there, and the combined perceptions of many humans, communicating with each other, using clever instruments to extend and quantify those senses, and employing the scientific method gives us a good chance of bringing our collective mental model closer and closer to the real thing, in pragmatic terms at least...

[Xamonas Chegwé]

Stare at this image with one eye closed for 20 seconds then click on the spoiler.

Trigger Warning!!!1! :

That's 20 seconds of your life you'll never, ever get back!

[FBM]

Do varying wavelenghts of light = color? As we all know, the electromagnetic spectrum extends far beyond what the human eye can detect. Is X-ray a color?

[macdoc]

No because it's not in our sensory spectrum but UV for certain species could be considered a colour as they can perceive it and alos because we could wear glasses that allow that perception.

But vision is not all color....there is a whole grey world that we perceive without resorting to color.
Colours are a construct that continues to develop and promotes arguments when wifey says your hunter green is blue. ( she's likely more correct due to some differences in male/femail vision )

That a color blind person cannot see say red does not mean red does not exist - just that he cannot percieve the section of the spectrum we have designated red as different from the spectrum ranges on either side....