The Island of the Colorblind

We had seen a beautifully patterned that outside the Edwards’ house, and now noticed similar ones everywhere, in front of the traditional thatched houses, and equally the newer ones, made of concrete blocks with corrugated aluminum roofs. The weaving of these mats was a craft unchanged from ‘the time before time,’ James told us; the traditional fibers, made from palm fronds, were still used (although the traditional vegetable dyes had been replaced by an inky blue obtained from surplus carbon paper, for which the islanders otherwise had little need). The island’s finest weaver was a colorblind woman, who had learned the craft from her mother, who was also colorblind. James took us to meet her; she was doing her intricate work inside a hut so dark we could hardly see anything after the bright sunlight. (Knut, on the other hand, took off his double sunglasses and said it was, visually, the most comfortable place he had yet encountered on the island.) As we adapted to the darkness, we began to see her special art of brightnesses, delicate patterns of differing luminances, patterns that all but disappeared as soon as we took one of her mats into the sunlight outside.

Recently, Knut told her, his sister, Britt, to prove it could be done, had knitted a jacket in sixteen different colors. She had devised her own system for keeping track of the skeins of wool, by labelling them with numbers. The jacket had marvellous intricate patterns and images drawn from Norwegian folktales, he said, but since they were done in dim browns and purples, colors without much chromatic contrast, they were almost invisible to normal eyes. Britt, however, responding to luminances only, could see them quite clearly, perhaps even more clearly than color-normals. ‘It is my special, secret art,’ she says. ‘You have to be totally colorblind to see it.’

Later in the day, we went to the island’s dispensary to meet more people with the maskun – almost forty people were there, more than half the achromatopes on the island. We set up in the main room – Bob with his ophthalmoscope, his lenses and acuity tests, and I with a mass of colored yarns and drawings and pens, as well as the standard color-testing kits. Knut had brought along a set of Sloan achromatopsia cards. I had never seen these before, and Knut explained the test to me: ‘Each of these cards has a range of grey squares which vary only in tone, progressing from a very light grey to a very dark grey, almost black, really. Each square has a hole cut out in the center, and if I place a sheet of colored paper behind these – like this – one of the squares will be a match for the color; they will have an equal density.’ He pointed to an orange dot, surrounded by a medium grey background. ‘For me the internal dot and the surround here are exactly the same.’

Such a match would be completely meaningless for a color-normal, for whom no color can ever ‘match’ a grey, and extremely difficult for most – but quite easy and natural for an achromatope, who sees all colors, and all greys, only as differing luminances. Ideally, the test should be administered with a standard source of illumination, but since there was no electricity to run lights on the island, Knut had to use himself as a standard, comparing each achromatope’s responses to his own. In nearly every case, these were the same, or very close.

Medical testing is usually rather private, but here it was very public, and with dozens of youngsters peering in through the windows, or wandering among us as we tested, took on a communal and humorous and almost festive quality.

Bob wanted to check refraction in each person, and to examine their retinas closely – by no means easy, when the eyes are continually jerking with nystagmus. It was not possible, of course, to see the microscopic rods and cones (or lack thereof) directly, but he could find nothing else amiss on inspection with his ophthalmoscope. It had been suggested by some earlier researchers that the maskun was linked with severe myopia; but Bob found that although many of the achromatopes were nearsighted, many were not (Knut himself is rather farsighted) – and he also found that a similar proportion of the island’s color-normals were nearsighted as well. If there were a genetic form of myopia here, Bob felt, it was transmitted independently of the achromatopsia.[20] It was possible as well, he added, that reports of nearsightedness had been exaggerated by earlier researchers who had observed so many of the islanders squinting and bringing small objects closer to view – behaviors which might appear to indicate myopia but actually reflected the intolerance of bright light and poor acuity of the achromatopes.