Color blindness is a subject near and dear to my heart. No, I am not color blind and I proved that to myself in class! What I mean is that my oldest sister, Karen, has this condition yet fails to acknowledge it! It reinforces the idea that perception has a subjective spin on it. To her, she is right; that blue car is indeed green and everyone else is color blind. What a silly girl.
I always knew my sister was a special gal. She is part of the 0.05% of females in the U.S. population who have some type of color deficiency. Only she has yet to admit it. Being the good sister that I am, I have decided to diagnose her. Of course this is only a very rudimentary evaluation. As I have mentioned before, she has a problem distinguishing between greens and blues. It seems likely that she has tritanomly, the rarest form of cone deficiency. Tritanomly means there is malfunctioning in the S cones which equals difficulty in distinguishing between blue and green.
Because color perception involves the actual wavelength that an object reflects AND the ratio of activity in our cones, people with deficiencies in the proper functioning of any of the cone types will have some type of color perception that is vastly different from people with normal functioning cones. In my sister’s case, if a certain object reflects the color green, the ratio of activity in her cones would indicate the color blue.
We can determine the objective color of an object by measuring the wavelength that it reflects. With experiments, we can determine whether or not a person perceives this color. Through matching tests where subjects turn a knob to match the color perfectly and through tests like the Ishihara, we can determine whether or not someone has deficiencies in their cones.
It’s not that my sister cannot completely see color. It’s not like she only sees gray when she looks at the color green. She only perceives it differently than people with normal functioning cones. In a website about tritanopias, the author mentions the fact that most people with this condition fail to even acknowledge it’s existence compared to the deuteranopias and protanopias. Because a big part of driving depends on differentiating between a red stop and a green go, when one has difficulties discerning these two colors, it’s very noticeable. But my sister can go through her entire life believing that the car is blue despite the rest of the family telling her it’s green.
It is very difficult to determine if someone else is perceiving the world in the same way as us. That is the reason why some people do not even know they have color blindness until they learn about the condition. There are numerous tests that one can take to determine color blindness, so we have these tools to help us in the quest. We can simulate how our cones are supposed to work, but we will never really know if something as subjective as color perception is the same in other people.
