The Mind's Eye

by Oliver Sacks

  Far worse than the loss of depth was the new limitation on the visual field. My right arm became covered in bruises from running into door frames because my brain was still reacting as if it was getting the full panorama from two eyes. I also often knocked objects off the table with my right arm. In fact, limited scope remains a problem even after 22 years, especially in crowded subway stations where people’s paths may suddenly and silently converge on my right, resulting in occasional, embarrassing collisions.

  Greenwich Avenue, and the outside world generally, remain as full of hazards, real and imaginary, as when I went for that first post-hemorrhage walk many weeks ago. People rush around, so preoccupied with cell phones and text messaging that they themselves are functionally deaf and blind, oblivious of their environment; others have tiny, insectlike dogs on long, invisible leashes, which function as trip wires for the visually impaired; children zip around beneath eye level on scooters. There are other dangers, too: manholes, grates, and fire hydrants, doors suddenly opening, cyclists delivering lunches—the entire scene seems designed to drum up business for orthopedists. I dare not walk alone; fortunately, my friends help out by walking with me, acting as guides and protectors on my blind side. And I would not dream of driving at this point.

  I try to stick to the right side of the sidewalk so that no one can overtake me on my blind side, but this is not always possible: the sidewalk is often crowded and not mine to commandeer as I might like. I find myself losing things on my own desk—my reading glasses, my fountain pen, a letter I have just written—if I have placed them to my right.

  And yet (so I am told, in Frank Brady’s book A Singular View: The Art of Seeing with One Eye) almost everyone who loses an eye does accommodate to its loss, more easily if they are young or if the loss of vision is gradual; especially too if the affected eye is not the dominant one and vision in the other eye is good. (I, alas, rank rather low on all these criteria.) Most people, given time, are able to return to a full and free life—so long, Brady emphasizes, as they retain a special mindfulness, a hyperconsciousness, of the missing side.

  Perhaps this will be possible for me, too, in the future. But it is far from my situation now. Strange incidents seem to beset me all the while. Returning the other day from a walk with my friend Billy, I “lost” him when I entered the elevator. I turned to the right and someone was standing there, someone who I thought for a moment must be Billy. Then I realized that it was a stranger, a stranger who himself looked surprised and puzzled, even slightly alarmed, at my turning and staring at him with a look of befuddlement. He must have thought I was mad. It was only when I twisted still farther to the right that I found Billy, to the left of the stranger, deep in my nowhere.

  Five minutes later, when we got to my apartment and I turned to put on a kettle for tea, Billy vanished again—but I discovered him, after a bewildered pause, precisely where I had left him. He had not moved, but my turning away had put him in my blind spot, my visual and mental “nowhere.” I was again astounded that this could happen within seconds, and in a way so contrary to memory and common sense. Each time this happens, it is just as startling.

  Time will tell whether I am able to adapt to this new visual challenge—or perhaps the hemorrhage will clear first and restore at least some peripheral vision to my right eye. In the meantime, I have a large “nowhere” in my right visual field and my brain, a nowhere of which I am not and can never be directly conscious. For me, people and objects continue to “disappear into thin air” or “come out of the blue”—these are no longer just metaphors for me, but as close as I can come to describing the experience of nothingness and nowhere.

  1. Many people with macular degeneration still manage to lead pretty full and independent lives. One patient of mine, a feisty old lady, told me that for five years after she lost central vision from macular degeneration, she “operated quite well on peripheral vision.” She could still take walks and find her way around, even though she was legally blind, with vision of 20/200 or less.

  2. Although Critchley coined the term “paliopsia,” most people now use “palinopsia.”

  3. Frigyes Karinthy, in Journey Round My Skull, describes a very different sort of filling in when he is losing his vision. It is not the sort of low-level filling in that I have, but a much more complex filling in at a higher level, one that draws on association and memory:

  By now, I had learnt to interpret every hint afforded by the shifting of light and to complete the general effect from memory. I was getting used to this strange semi-darkness in which I lived, and I almost began to like it. I could still see the outline of figures pretty well, and my imagination supplied the details, like a painter filling an empty frame. I tried to form a picture of any face I saw in front of me by observing the person’s voice and movements. People were often astonished to see that I could not distinguish between colours and shades, yet I would catch momentary facial expressions unnoticed by those with normal eyesight. I, too, was surprised. The idea that I might already have gone blind struck me with sudden terror.… I might only be using people’s words and voices to reconstruct the lost world of reality, just as our mind, at the moment we fall asleep, forms images resembling those of real life from the phosphenes that dance before our closing eyes. I stood on the threshold of reality and imagination, and I began to doubt which was which. My bodily eye and my mind’s eye were blending into one, and I could no longer be certain which of the two was really in control.

  4. There have, however, been two incidents that I am hard put to explain. I had smoked a little cannabis both times, and I found myself totally absorbed, gazing in a sort of rapture at flowers—some narcissus in a pot on one occasion and morning glories twining up a fence on the other. Both times, it seemed to me, the flowers filled out before my eyes, thrust themselves into the space around them, assuming their full and proper three-dimensional glory. They deflated once again when the cannabis wore off. Was this vision “real” or an illusion? It was wholly different in quality from the pseudostereo, the confounding illusions of depth and distance I would sometimes have with lines on the ground, where there was not, in reality, any depth at all. The flowers did have depth, and I was seeing them as I used to when I had two good eyes. If it was an aberrant perception or an illusion, it was a veridical one, consonant with reality.

  Some of my correspondents have occasionally experienced an opposite effect with cannabis—a loss of stereo, so that their visual world seems two-dimensional, like a painting.

  5. Gradually the peripheral vision in my right eye got worse, as a cataract developed in reaction to the radiation treatment. With this, what little stereopsis I had diminished. When I had the cataract removed in the spring of 2009, I had a sudden resurgence of peripheral vision and stereopsis. Everything looked, with my right eye, brigher and bluer, and when I went to the orchid show at the botanical garden the next day, I not only saw colors with a startling brilliance and freshness, but I could see flowers thrusting towards me in the bottom of my visual field. I rejoiced in this, but did not realize how short-lived my return to (at least partial) stereo would be.

  6. There may be various optical or mechanical ways to enlarge the visual field if an eye is lost. The use of a prism, for example, may allow an extra six or eight degrees of visual field, and there may be ingenious strategies with mirrors, too. A more drastic solution was attempted by Federico, a fifteenth-century duke of Urbino who had lost one eye in a tournament. Fearing the ever-present threat of assassination and wanting to preserve his prowess on the battlefield, he had his surgeons amputate the bridge of his nose to allow a wider field for the remaining eye.

  7. I wrote about this patient in “Eyes Right!” in The Man Who Mistook His Wife for a Hat. Another example was provided by my colleague M.-Marsel Mesulam, who wrote, “When the neglect is severe, the patient may behave almost as if one half of the universe had abruptly ceased to exist in any meaningful form.… Patients with unilateral neglect behave not only as if noth
ing were actually happening in the left hemispace, but also as if nothing of any importance could be expected to occur there.”

  8. John Hull, who became totally blind in midlife, describes this sense of suddenness in Touching the Rock:

  For the blind, people are not there unless they speak. Many times I have continued a conversation with a sighted friend only to discover that he is not there. He may have walked away without telling me. He may have nodded or smiled, thinking the conversation was over. From my point of view, he has suddenly vanished.

  When you are blind, a hand suddenly grabs you. A voice suddenly addresses you. There is no anticipation or preparation.… I am passive in the presence of that which accosts me.… The normal person can choose whom he wants to speak to, as he wanders around the streets or the market-place. People are already there for him; they have a presence prior to his greeting them.… For the blind person, people are in motion, they are temporal, they come and they go. They come out of nothing; they disappear.

  The Mind’s Eye

  TO WHAT EXTENT are we the authors, the creators, of our own experiences? How much are these predetermined by the brains or senses we are born with, and to what extent do we shape our brains through experience? The effects of a profound perceptual deprivation such as blindness may cast an unexpected light on these questions. Going blind, especially later in life, presents one with a huge, potentially overwhelming challenge: to find a new way of living, of ordering one’s world, when the old way has been destroyed.

  In 1990, I was sent an extraordinary book called Touching the Rock: An Experience of Blindness, by John Hull, a professor of religious education in England. Hull had grown up partly sighted, developing cataracts at the age of thirteen and becoming completely blind in his left eye four years later. Vision in his right eye remained reasonable until he was thirty-five or so, but there followed a decade of steadily failing vision, so that Hull needed stronger and stronger magnifying glasses and had to write with thicker and thicker pens. In 1983, at the age of forty-eight, he became completely blind.

  Touching the Rock is the journal he dictated in the three years that followed. It is full of piercing insights about his transition to life as a blind person, but most striking for me was his description of how, after he became blind, he experienced a gradual attenuation of visual imagery and memory, and finally a virtual extinction of them (except in dreams)—a state that he called “deep blindness.”

  By this, Hull meant not only a loss of visual images and memories but a loss of the very idea of seeing, so that even concepts like “here,” “there,” and “facing” seemed to lose meaning for him. The sense of objects having appearances, or visible characteristics, vanished. He could no longer imagine how the numeral 3 looked unless he traced it in the air with his finger. He could construct a motor image of a 3, but not a visual one.

  At first Hull was greatly distressed by this: he could no longer conjure up the faces of his wife or children, or of familiar and loved landscapes and places. But he then came to accept it with remarkable equanimity, regarding it as a natural response to losing his sight. Indeed, he seemed to feel that the loss of visual imagery was a prerequisite for the full development, the heightening, of his other senses.

  Two years after becoming completely blind, Hull had apparently become so nonvisual in his imagery and memory as to resemble someone who had been blind from birth. In a profoundly religious way, and in language sometimes reminiscent of that of Saint John of the Cross, Hull entered into the state of deep blindness, surrendered himself, with a sort of acquiescence and joy. He spoke of deep blindness as “an authentic and autonomous world, a place of its own.… Being a whole-body seer is to be in one of the concentrated human conditions.”

  Being a “whole-body seer,” for Hull, meant shifting his attention, his center of gravity, to the other senses, and these senses assumed a new richness and power. Thus he wrote of how the sound of rain, never before accorded much attention, could delineate a whole landscape for him, for its sound on the garden path was different from its sound as it drummed on the lawn, or on the bushes in his garden, or on the fence dividing the garden from the road:

  Rain has a way of bringing out the contours of everything; it throws a coloured blanket over previously invisible things; instead of an intermittent and thus fragmented world, the steadily falling rain creates continuity of acoustic experience … presents the fullness of an entire situation all at once … gives a sense of perspective and of the actual relationships of one part of the world to another.

  With his new intensity of auditory experience (or attention), along with the sharpening of his other senses, Hull came to feel a sense of intimacy with nature, an intensity of being-in-the-world, beyond anything he had known when he was sighted. Blindness became for him “a dark, paradoxical gift.” This was not just “compensation,” he emphasized, but a whole new order, a new mode of human being. With this, he extricated himself from visual nostalgia, from the strain or falsity of trying to pass as “normal,” and found a new focus, a new freedom and identity. His teaching at the university expanded, became more fluent; his writing became stronger and deeper; he became intellectually and spiritually bolder, more confident. He felt he was on solid ground at last.1

  Hull’s description seemed to me an astounding example of how an individual deprived of one form of perception could totally reshape himself to a new center, a new perceptual identity. Yet I found it extraordinary that such an annihilation of visual memory as he described could happen to an adult with decades of rich and significant visual experience to call upon. I could not, however, doubt the authenticity of Hull’s account, which he related with the most scrupulous care and lucidity.

  Cognitive neuroscientists have known for the past few decades that the brain is far less hardwired than was once thought. Helen Neville was one of the pioneers here, showing that in prelingually deaf people (that is, those who had been born deaf or become deaf before the age of two or so) the auditory parts of the brain did not degenerate. They remained active and functional, but with an activity and a function that were new: they were transformed, “reallocated,” in Neville’s term, for processing visual language. Comparable studies in those born blind, or blinded early, show that some areas of the visual cortex may be reallocated and used to process sound and touch.

  With this reallocation of parts of the visual cortex, hearing, touch, and other senses in the blind can take on a hyperacuity that perhaps no sighted person can imagine. Bernard Morin, the mathematician who showed in the 1960s how a sphere could be turned inside out, became blind at the age of six, from glaucoma. He felt that his mathematical achievement required a special sort of spatial sense—a haptic perception and imagination beyond anything a sighted mathematician was likely to have. And a similar sort of spatial or tactile giftedness has been central to the work of Geerat Vermeij, a conchologist who has delineated many new species of mollusks, based on tiny variations in the shapes and contours of their shells. Vermeij has been blind since the age of three.2

  Faced with such findings and reports, neuroscientists began to concede in the 1970s that there might be a certain flexibility or plasticity in the brain, at least in the first couple of years of life. But when this critical period was over, it was thought, the brain became much less plastic.

  Yet the brain remains capable of making radical shifts in response to sensory deprivation. In 2008, Lotfi Merabet, Alvaro Pascual-Leone, and their colleagues showed that, even in sighted adults, as little as five days of being blindfolded produced marked shifts to nonvisual forms of behavior and cognition, and they demonstrated the physiological changes in the brain that went along with this. (They feel it is important to distinguish between such rapid and reversible changes, which seem to make use of preexisting but latent intersensory connections, and the long-lasting changes that occur especially in response to early or congenital blindness, which may entail major reorganizations of cortical circuitry.)

  Apparently H
ull’s visual cortex, even in adulthood, had adapted to a loss of visual input by taking over other sensory functions—hearing, touch, smell—while relinquishing the power of visual imagery. I assumed that Hull’s experience was typical of acquired blindness, the response, sooner or later, of everyone who loses sight—and a brilliant example of cortical plasticity.

  Yet when I came to publish an essay on Hull’s book in 1991, I was taken aback to receive a number of letters from blind people, letters that were often somewhat puzzled and occasionally indignant in tone. Many of these people wrote that they could not identify with Hull’s experience and said that they themselves, even decades after losing their sight, had never lost their visual images or memories. One woman, who had lost her sight at fifteen, wrote:

  Even though I am totally blind … I consider myself a very visual person. I still “see” objects in front of me. As I am typing now I can see my hands on the keyboard.… I don’t feel comfortable in a new environment until I have a mental picture of its appearance. I need a mental map for my independent moving, too.

  Had I been wrong, or at least one-sided, in accepting Hull’s experience as a typical response to blindness? Had I been guilty of emphasizing one mode of response too strongly, oblivious to other, radically different possibilities?

  This feeling came to a head a few years later, when I received a letter from an Australian psychologist named Zoltan Torey. Torey wrote to me not about blindness but about a book he had written on the brain-mind problem and the nature of consciousness. In his letter he also mentioned that he had been blinded in an accident at the age of twenty-one. But although he was “advised to switch from a visual to an auditory mode of adjustment,” he had moved in the opposite direction, resolving to develop instead his inner eye, his powers of visual imagery, to their greatest possible extent.