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A Whiter White

Some years ago my eye doctor told me I was developing cataracts. He said it almost in passing, assuring me the condition was not uncommon for someone my age. The symptoms were slow to progress. Still, I was surprised. I was familiar with Claude Monet’s struggles to continue painting as cataracts clouded his vision. You can actually see evidence of his condition in his iconic paintings of water lilies. The colors are muddier and the brush strokes less distinct than in his earlier work. My own vision gradually grew cloudy, but there was none of the yellowish tint that cataract patients normally report – or at least so it appeared until I had my cataracts removed.

Cataract surgery is performed on each eye in turn, spaced several weeks apart. During that in-between period, I wore my old glasses with one lens removed, since the ophthalmologist had also corrected an astigmatism in my right eye. I could now see clearly at a distance out of that eye but not out of the other one. A week or so after my first surgery, I happened to look out my bedroom window. Snow had fallen during the night, and I noticed a small but distinct yellowish tint to the snow through my uncorrected left eye but not through my right. How had I failed to see this before?

As a photographer, I depend not only on visual acuity but also color discrimination in my work. Color correction is normally part of the post-production process, using Photoshop or similar software. The first step is usually to adjust the white balance so that white objects in an image are truly white. If you shoot indoors, the camera will record a yellowish cast from incandescent lighting or a bluish cast from fluorescent fixtures. You can adjust for this during color correction so the image appears more natural.

One of the oddities of human vision is that it will automatically adjust for changes in lighting to make sure white objects always appear white – a phenomenon that cognitive psychologists refer to as “color constancy.” However, a camera will dutifully record the colors as they actually are, requiring adjustments in the color balance so the image appears the way the eye sees the scene. As I discovered, the eye’s internal color correction mechanism also counteracts any changes caused by cataracts to assure that snow always appears white, not pale yellow.

Clearly, color is not an exclusive property of the objects we perceive in the world, as Galileo believed. But neither is it necessarily in the eye of the beholder; otherwise, I would have seen yellow snow through my cataracts. I can only conclude the color palette I apply to the world resides in my mind’s eye, the part of my brain that determines what the colors should be and paints things accordingly. Snow, for example, is supposed to be white, so my brain finds a match with my internal image of snow, kind of like comparing color swatches at the paint store.

Where do those mental color swatches come from? Physiologically, the human eye is capable of perceiving millions of shades of color. But what do we actually see? Recent research suggests that color discrimination may be determined in part by language and culture. For example, the English language has 11 basic color words (red, green, blue, etc.), while the Himba people of Namibia have only five, each term covering a broader range on the color spectrum. Meanwhile, the language spoken by the Candoshi tribe on the upper Amazon River has no color words at all, not even a concept of color as such. This despite the fact the Candoshi spend much of their time making brightly colored dyes and pigments for pottery and face paints.

The recent findings on color discrimination among different cultures tend to validate a disputed theory put forward by linguist Benjamin Whorf, who argued that language determines to a significant degree what we think and how we see the world. His study of Native American languages suggested that indigenous peoples interpreted the world in ways that were radically different from Western cultures, including their basic understanding of time and space. "The world is presented in a kaleidoscopic flux of impressions which has to be organized by our minds -- and this means largely by the linguistic systems in our minds," Whorf wrote in Language, Thought and Reality (1956). "We cut nature up, organize it in this way, largely because we are parties to an agreement to organize it in this way -- an agreement that holds throughout our speech community and is codified in the patterns of our language."

As it happens, one of the examples Whorf used was snow, which is denoted with a single word in English and multiple words in the Eskimo language, enabling Eskimos to make much finer distinctions when discussing the white stuff. Critics challenged Whorf’s conclusions, and his theory had long since fallen out of favor. But now the recent research on color discrimination has breathed new life into the idea that language shapes perception. In effect, we don’t just put words to the things we see, we see what we have words for. And if we only see the colors we can name, what else aren’t we seeing?

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