The Island of the Colorblind

Knut’s eyes, like those of other congenital achromatopes, have no cones (at least no functional cones): these are the cells which, in the rest of us, fill the fovea – the tiny sensitive area in the center of the retina – and are specialized for the perception of fine detail, as well as color. He is forced to rely on the more meager visual input of the rods, which, in achromatopes as in the rest of us, are distributed around the periphery of the retina, and though these cannot discriminate color, they are much more sensitive to light. It is the rods which we all use for low-light, or scotopic, vision (as, for instance, walking at night). It is the rods which provide Knut with the vision he has. But without the mediating influence of cones, his rods quickly blanch out in bright light, becoming almost nonfunctional; thus Knut is dazzled by daylight, and literally blinded in bright sunlight – his visual fields contract immediately, shrinking to almost nothing – unless he shields his eyes from the intense light.

His visual acuity, without a cone-filled fovea, is only about a tenth of normal – when we were given menus, he had to take out a four-power magnifying glass and, for the special items chalked on a blackboard on the opposite wall, an eight-power monocular (it looked like a miniature telescope); without these, he would barely be able to read small or distant print. His magnifying glass and monocular are always on his person, and like the dark glasses and visors, they are essential visual aids. And, with no functioning fovea, he has difficulty fixating, holding his gaze on target, especially in bright light – hence his eyes make groping, nystagmic jerks.

Knut must protect his rods from overload and, at the same time, if detailed vision is needed, find ways of enlarging the images they present, whether by optical devices or peering closely. He must also, consciously or unconsciously, discover ways of deriving information from other aspects of the visual world, other visual cues which, in the absence of color, may take on a heightened importance. Thus – and this was apparent to us right away – his intense sensitivity and attention to form and texture, to outlines and boundaries, to perspective, depth, and movements, even subtle ones.

Knut enjoys the visual world quite as much as the rest of us; he was delighted by a picturesque market in a side street of Honolulu, by the palms and tropical vegetation all around us, by the shapes of clouds – he has a clear and prompt eye for the range of human beauty too. (He has a beautiful wife in Norway, a fellow psychologist, he told us – but it was only after they married, when a friend said, ‘I guess you go for redheads,’ that he learned for the first time of her flamboyant red hair.)

Knut is a keen black-and-white photographer – indeed his own vision, he said, by way of trying to share’it, has some resemblance to that of an orthochromatic black-and-white film, although with a far greater range of tones. ‘Greys, you would call them, though the word ‘grey’ has no meaning for me, any more than the term ‘blue’ or ‘red.’’ But, he added, ‘I do not experience my world as ‘colorless’ or in any sense incomplete.’ Knut, who has never seen color, does not miss it in the least; from the start, he has experienced only the positivity of vision, and has built up a world of beauty and order and meaning on the basis of what he has.[5]

As we walked back to our hotel for a brief night’s sleep before our flight the next day, darkness began to fall, and the moon, almost full, rose high into the sky until it was silhouetted, seemingly caught, in the branches of a palm tree. Knut stood under the tree and studied the moon intently with his monocular, making out its seas and shadows. Then, putting the monocular down and gazing up at the sky all around him, he said, ‘I see thousands of stars! I see the whole galaxy!’

‘That’s impossible,’ Bob said. ‘Surely the angle subtended by a star is too small, given that your visual acuity is a tenth of normal.’

Knut responded by identifying constellations all over the sky – some looked quite different from the configurations he knew in his own Norwegian sky. He wondered if his nystagmus might not have a paradoxical benefit, the jerking movements ‘smearing’ an otherwise invisible point image to make it larger – or whether this was made possible by some other factor. He agreed that it was difficult to explain how he could see stars with such low visual acuity – but nonetheless, he did.

‘Laudable nystagmus, eh?’ said Bob.