Colors in the Mind

by Brian

My dad was colorblind. Once I was old enough to understand what that meant, I wanted to know what that was like for him. I thought it would be like black-and-white versus color television: that he would be seeing film noir all the time while I would be seeing Gone with the Wind.

It’s not like that, of course, and while I don’t know what he saw, it’s pretty clear that he saw a colored world of some kind. I’m not sure it was even that different from mine. Different, yes. But how different?

Some research published in the Journal of Neuroscience about a year ago suggests—again—that color is in the mind, not “in the the world.” There is something out there in the world, but the color is added largely by the brain. As ScienceDaily put it in a summary of the paper:

Researchers at the University of Rochester have found that the number of color-sensitive cones in the human retina differs dramatically among people—by up to 40 times—yet people appear to perceive colors the same way. The findings, on the cover of this week’s journal Neuroscience, strongly suggest that our perception of color is controlled much more by our brains than by our eyes.

“We were able to precisely image and count the color-receptive cones in a living human eye for the first time, and we were astonished at the results,” says David Williams, Allyn Professor of Medical Optics and director of the Center for Visual Science. “We’ve shown that color perception goes far beyond the hardware of the eye, and that leads to a lot of interesting questions about how and why we perceive color….”

“Those early experiments showed that everyone we tested has the same color experience despite this really profound difference in the front-end of their visual system,” says Hofer. “That points to some kind of normalization or auto-calibration mechanism—some kind of circuit in the brain that balances the colors for you no matter what the hardware is.”

In another experiment, researchers

gave several people colored contacts to wear for four hours a day. While wearing the contacts, people tended to eventually feel as if they were not wearing the contacts, just as people who wear colored sunglasses tend to see colors “correctly” after a few minutes with the sunglasses. The volunteers’ normal color vision, however, began to shift after several weeks of contact use. Even when not wearing the contacts, they all began to select a pure yellow that was a different wavelength than they had before wearing the contacts [emphasis added].

“Over time, we were able to shift their natural perception of yellow in one direction, and then the other,” says Williams. “This is direct evidence for an internal, automatic calibrator of color perception. These experiments show that color is defined by our experience in the world, and since we all share the same world, we arrive at the same definition of colors.”

“T’is nothing either yellow or blue, but thinking makes it so,” Hamlet might have said.