How are we sure that we see the same colours?

Question

My point is that. When I define something as green how do I know that green is green for the others and not red. God I am so desperate I cannot explain it exactly.

Answer 1

You only miss colours if you're colour blind..

Answer 2

I know what you mean and I've pondered itself. You're wondering if everyone sees the same thing if they look at a green sign, for instance.
Objects get their color from the light that bounces off of them. The color depends on the wavelength of the reflected light from the object (about 520-570 nanometers for green, 625-750 for red, and so on). The receptors in the eyes pick up the differences in wavelength and interpret them as color. Since all humans who can see color have more or less the same equipment in their eyes, I would say that yes, everyone sees individual colors in about the same way. Some people with eyes more or less sensitive than others may see slight differences others wouldn't, but green is green is green, pretty much. Probably everyone sees it the same way.

Answer 3

It's an agreement between you and other people. You can't describe green other than to say it is like other things you see that are also green. Other people see the same things, and agree on the changes of shade. We know the physical processes that send messages to the brain about colours, we can assume that our brains process them in pretty much the same way. So we should all agree on the colours of objects. If you saw through an insects eye, which has sensitivities to different light wavelengths, then you would not agree with people with human eyes.

The effect of colours on different people may not be the same. People with synesthesia see numbers as colours, and colours as numbers. This is not how everyone perceives colours so it would seem although we agree what colour is green it doesn't affect each of us in the same way.

The reference article is pretty interesting.

Answer 4

I know exactly what you mean and exactly how difficult it is to explain. I don't think there is any was of testing it though.

The question is nothing to do with colour blindness, its about what I see as "green" being what you see as "green". For traffic lights you know that if the one that you know as being "Red" is lit then you stop. You see "red" or "green" based on what somebody once told you were red and green. You know that the various shades of these colours are still red and green but you don't know that anybody else sees them in the same way that you do.

Answer 5

The perception of colours is structurally defined. Imagine you saw black as white and vice versa. You would then be dazzled by "bright" black, which is impossible, so that allows you to determine that black can only be black and white white. Then there is the issue of violet and red, which incidentally have the same name in many languages. Violet to the human eye looks "redder" than blue does, so that's another structural phenomenon. This similarity could be measured by the response of cone cells to violet and red radiation. If green looked red to other people, violet would be green-blue and not red-blue, and since green-blue is not violet, it would be impossible to see green as red and vice versa, although it is possible to be red-green colourblind.

It's probably possible to define other colours in this way too.

You could try reading "Remarks on Colour" by Wittgenstein, which is quite relevant to this, and "Basic Colour Terms", which is a classic work on the linguistics of colour.

Incidentally, this is a philosophical or psychological question, not an astronomical one.

Answer 6

In The Amazing Brain, R. Ornstein and R. F. Thompson have stated the way colors are formed as follows.

'Color' as such does not exist in the world; it exists only in the eye and brain of the beholder. Objects reflect many different wavelengths of light, but these light waves themselves have no color.6
http://www.harunyahya.com/matter2.php




MATTER: The Other Name for Illusion

What is explained in this book is an important truth, which has surprised many and changed their perspectives on life. This truth can be summarized as follows: "All events and objects that we encounter in real life-buildings, people, cities, cars, places-in fact, everything we see, hold, touch, smell, taste and hear-come into existence as visions and feelings in our brains".

We are taught to think that these images and feelings are caused by a solid world outside of our brains, where material things exist. However, in reality we never see real existing materials and we never touch real materials. In other words, every material entity which we believe exists in our lives, is, in fact, only a vision which is created in our brains.

This is not a philosophical speculation. It is an empirical fact that has been proven by modern science. Today, any scientist who is a specialist in medicine, biology, neurology or any other field related to brain research would say, when asked how and where we see the world, that we see the whole world in the vision center located in our brains.

This fact has been scientifically proven in the twentieth century, and although it may seem surprising, it necessarily implies answers to two questions; "If our lives are visions created in our brains, then who is it that creates these visions? And who is it that sees these visions in our brains without having eyes and enjoys them, gets excited and happy?" You will find the answers to these two important questions in this book.

Answer 7

Even if you see something green and somebody else sees it as a different color, you both agree on the same one, because eventhough you see it differently you will call the color same name as you have been tought it as children. Anyway if I see a red apple and you think it is a green apple, we both say that is red, because you call your green red.

Answer 8

When you picture green , you are imagining a universal in your mind of what is green , When you see the object and notice other objects were of the same color and were designated as green then we call this object green.

Answer 9

Color is dependent on light, so green as you see it, will look markedly different in the presence of different light sources. A green apple is still a green apple in a darkened room, your eyes would just perceive it as a black apple. In direct sunlight, that same green apple might look significantly lighter, than in your kitchen.

Also, color is a wavelength of light, which is how color can be measured and named as red color (shorter wavelength), or green color (longer wavelength).

Answer 10

There are tests where people who see different colors will see different letters in the dot tests that many take to check for color blindness. The dots are carefully chosen colors that form patterns of letters depending on how you see colors. They can also examine the eye to see the layout of the different types of photoreceptors dedicated to color called cones. Both ways are pretty good about testing that most of us consistently see color the same.

Answer 11

You don't. I was always led to believe that everyone see's colour differently.
People who are colour blind obviously see some colours very differently to others. But we all see the spectrum of colours slightly differently.