What the blind see
Sense and Sensibility 'To become blind represents one with a potentially overwhelming challenge:to find a new way of living,of ordering one's world,when the old way has been destroyed'

Do we control our brains or do our brains control us? Oliver Sacks, the author and neurologist, describes how the experiences of blind people provide a fascinating insight into the nature of consciousness.

In the last letter he wrote,Goethe observed: "The Ancients said that the animals are taught through their organs; let me add to this, so are men, but they have the advantage of teaching their organs in return." He wrote this in 1832, a time when phrenology was at its height, and the brain was seen as a mosaic of "little organs" subserving everything from language to drawing ability to shyness. Each individual, it was believed, was given a fixed measure of this or that faculty, according to the luck of his birth.

Although we no longer pay attention, as the phrenologists did, to "bumps" on the head (each of which, supposedly, indicated a brain-mind organ beneath), neurology a and neuroscience have stayed close to the idea of brain fixity and localisation - the notion, in particular, that the highest part of the brain, the cerebral cortex, is effectively programmed from birth: this part to vision and visual processing, that part to hearing, that to touch, and so on. This would seem to allow individuals little power of choice, of self-determination, let alone of adaptation, in the event of a neurological or perceptual mishap.

But to what extent are we - our experiences, our reactions - shaped, predetermined, by our brains, and to what extent do we shape our own brains? Does the mind run the brain or the brain run the mind - or, rather, to what extent does one run the other? To what extent are we the authors,the creators,of our own experiences? The effects of profound blindness can cast an unexpected light on this. To become blind,especially in later 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.

A DOZEN YEARS ago, I was sent an extraordinary book called Touching the Rock: An Experience of Blindness. The author, John Hull, was a professor of religious education who had grown up in Australia and then moved to England. Hull had developed cataracts at the age of 13, and became blind in his left eye four years later. Vision in his right eye remained reasonable until he was 35 or so, and then it started to deteriorate. There followed a decade of steadily failing vision, until, in 1983, at the age of 48, he became completely blind.

Touching the Rock is the journal he dictated in the three years that followed. It is full of piercing insights relating to Hull's life as a blind person, but most striking for me is Hull's description of how 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 the loss of visual images and memories, but a loss of the very idea of seeing, so that even the sense of objects having "appearances", visible characteristics, vanished. He could no longer, for example, imagine how the numeral 3 looked unless he traced it in the air with his hand. He could construct "motor " image of a 3, but not a  visual one. Though at first greatly distressed about the fading of visual memories and images, Hull came to accept it with remarkable equanimity. He seemed to regard this loss of visual imagery as a prerequisite for the full development, the heightening, of his other senses.

Two years after becoming completely blind, Hull had apparently become so non-visual as to resemble someone who had been blind from birth. In a profoundly religious way, and in language sometimes reminiscent of that of St John of the Cross, Hull has entered into this state, surrendered himself with a sort of acquiescence and joy. And such "deep" blindness he conceives 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, means shifting his attention, his centre of gravity, to the other senses, and he writes again and again of how these have assumed a new richness and power. Thus he speaks of how the sound of rain can now delineate a whole landscape for him, for its sound on the garden path is different from its sound as it drums on the lawn, or on the bushes in his garden. "Rain," he writes, "has a way of bringing out the contours of everything; it throws a coloured blanket over previously invisible things; instead of a fragmented world, the steadily falling rain creates continuity of acoustic experience...presents the fullness of an entire situation all at once."

Hull comes to feel an intensity of being-in-the-world, beyond anything he knew when he was sighted. Blindness now becomes for him "a dark, paradoxical gift". This is not just "compensation" he emphasises, but a whole new mode of human being.
It seemed extraordinary to me that such an annihilation of visual memory as Hull describes could happen to an adult, with an entire lifetime of rich and richly categorised visual experience to call upon. And yet I could not doubt the authenticity of Hull's account, which he relates with the most scrupulous care and lucidity.

Important studies of adaptation in the brain were begun in the 1970s by, among others, Helen Neville, a cognitive neuroscientist now working in Oregon. She showed 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 had not degenerated or atrophied. These had remained active and functional, but with an activity and a function that were new: they had been transformed, "reallocated" in Neville's term, for processing visual language. Comparable studies in those born blind, or early blinded, show that the visual areas of the cortex, similarly, may be reallocated in function, and used to process sound and touch.

'Even though I am totally blind I consider myself a visual person.I "see" objects. I can see my hands typing the keyboard now'

With the reallocation of the visual cortex to touch and other senses, these can take on a hyperacuity that perhaps no sighted person can imagine. Geerat Vermeij, a blind biologist, has been able to delineate many new species of mollusc based on tiny variations in the shapes and contours of their shells.

Faced with such evidence, neurologists began to concede that there might be a certain flexibility or plasticity in the brain, at least in the early years of life. But when this critical period was over, it was assumed, the brain became inflexible, and no further changes of a radical type could occur. The experiences that Hull so carefully recounts give the lie to this. It is clear that his perceptions, his brain, did finally change, in a fundamental way. Indeed, Alvaro Pascual-Leone and his colleagues in Boston have recently shown that, even in adult sighted volunteers, as little as five days of being blindfolded produces marked shifts to non-visual forms of behaviour and cognition, and they have demonstrated the physiological changes in the brain that go along with this.

The brain, clearly, is capable of changing even in adulthood, and I assumed that Hull's experience was typical of acquired blindness - the response, sooner or later, of everyone who becomes blind, even in adult life.
So 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 in tone were often somewhat puzzled, and occasionally indignant. Many of my correspondents, could not identify with Hull's experience, and said that they, even decades after losing their sight, had never lost their visual images or memories. One correspondent, who had lost her sight at 15, 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 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 emphasising the mode of response too strongly, oblivious to the possibilities of radically different responses?
This feeling came to a head in 1996,when I received a letter from an Australian psychologist named Zoltan Torey. Torey wrote to me not about blindness but about,The Crucible of Consciousness,which he had written on the mind/brain problem and the nature of consciousness. Torey spoke of how he had been blinded in an accident at the age of 21, while working at a chemical factory, and how, although "advised to switch from a visual to an auditory mode of adjustment", he had moved in the opposite direction, and resolved to develop instead his "inner eye", his powers of visual imagery, to their greatest possible extent.

In this, it seemed, he had been extremely successful, developing a remarkable power of generating, holding, and manipulating his mind, so much so that he had been able to construct an imagined visual world that seemed almost as real and intense to him as the perceptual one he had lost - and, indeed, sometimes more real, more intense, a sort of controlled dream or hallucination. This imagery, moreover, enabled him to do things that might have seemed scarcely possible for a blind man.

"I replaced the entire roof guttering of my multi-gabled home single-handed," he wrote, "and solely on the strength of the accurate and well-focused manipulation of my now totally pliable and responsive mental space." (Torey later expanded on this episode, mentioning the great alarm of his neighbours at seeing a blind man, alone, on the roof of his house - and, even more terrifying to them, at night, in pitch darkness).
Torey was able to think in ways that had not been available to him before, to envisage solutions, models, designs; to project himself into the inside of machines and other systems, and, finally, to grasp by visual thought and simulation (complemented by all the data of neuroscience) the complexities of that ultimate system, the human brain-mind.

In his new memoir, Out of Darkness, he explores how his life has been affected by blindness. Torey's father was the head of a large film studio in Hungary before the war and would often give his son scripts to read. "This," Torey writes, "gave me the opportunity to visualise stories, plots and characters, to work my imagination - a skill that was to become a lifeline and source of strength in the years ahead."
In June, 1951, loosening the plug in a vat of acid at the chemical factory where he worked, 22-year-old Torey had the accident that bisected his life. When it became clear that he would have to live his life as a blind man, he was advised to rebuild his representation of the world on the basis of hearing and touch and to "forget about sight and visualising altogether". But this was something that Torey could not or would not do.

He emphasised to me the importance of a most critical choice at this juncture: "I immediately resolved to find out how far a partially sense-deprived brain could go to rebuild a life." Put this way, it sounds abstract, like an experiment. But in his book one senses the tremendous feelings underlying his resolution - the horror of "the empty darkness", "the grey fog that was engulfing me -and the passionate desire to hold on to light and sight, to maintain, if only in memory and imagination, a living visual world.

John Hull, who did not use his potential for imagery in a deliberate way, lost it in two or three years, and became unable to remember which way round a 3 went; Torey, on the other hand, soon became able to multiply four-figure numbers by each other, as on a blackboard, visualising the whole operation in his mind.
Torey maintained a cautious and "scientific" attitude to his own visual imagery, taking pains to check the accuracy of his images by every means available. "I learned to hold the image in a tentative way, conferring credibility and status on it only where some information would tip the balance in its favour.

He became able "to imagine,to visualise for example, the inside of a differential gearbox in action - as if from inside it's casing. I was able to watch the cogs bite, lock and revolve, distributing the spin as required. I began to play around with this internal view in connection with mechanical and technical problems visualising how subcomponents relate in the atom, or the living cell." This powerful imagery was crucial, Torey thought, in enabling him to arrive at a solution of the brain-mind problem by visualising the brain "as a perpetual juggling act of interacting routines."

Living in the world of the blind

SOON AFTER READING Torey's manuscript, I received proofs of yet another memoir by a blind person: Sabriye Tenberken's My Path Leads to Tibet. Tenberken has travelled, often alone, throughout Tibet, where for centuries blind people have been treated as less than human and denied education, work or any role in the community. Almost single handedly, Tenberken transformed the prospects of blind people over the past half-dozen years, devising a form of Tibetan Braille, establishing schools for the blind, and integrating the graduates of these schools into their communities.

Photo:Paul Kronenburg
Sabriye Tenberken,who has devised a form of Tibetan Braille 'Tenberken continues to use all her other senses...to construct "pictures" of environments - pictures so lively and detailed as to astonish her listeners'

Tenberken herself impaired vision almost from birth, but was able to make out faces and landscapes until she was 12.As a child in Germany, she had a particular predilection for colours, and loved painting, and when she was no longer able to decipher shapes and forms she could still use colours to identify objects. Tenberken has, indeed an intense synaesthesia.

"As far back as I can remember," she writes, "numbers and words have instantly triggered colours in me ... number four, for example [is] gold. Five is light green.Nine is vermillion... Days of week, as well as months, have their colours, too." Her synaesthesia has persisted and been intensified, it seems,by her blindness.
Though she has been totally blind for 20 years now, Tenberken continues to use all her other senses, along with verbal descriptions, visual memories and a strong pictorial and aesthetic sensibility, to construct "pictures" of landscapes and rooms, ,of environments and scenes - pictures so lively and detailed as to astonish her listeners. These images may sometimes be wildly or a comically different from reality, as she relates in one incident when she and a companion drove to Nam Co, the great saltlake in Tibet. Turning eagerly towards the lake,Tenberken saw in her mind's eye, "a beach of crystallised salt shimmering like snow under an evening sun,at the edge of a vast body of water".But it then turns out that she had been facing in the wrong direction,not "looking" at the lake at all.

These disparities do not faze her in the least - she is happy to have so vivid a visual imagination. Hers is essentially an artistic imagination, which can be impressionistic, romantic: whereas Torey's imagination is that of an engineer, and has to be factual, accurate down to the last detail.
There is increasing evidence from neuroscience for the extraordinarily rich interconnectedness and interactions of the sensory areas of the brain, and the difficulty, therefore, of saying that anything is purely visual or purely auditory, or purely anything. The world of the blind, of the blinded, it seems, can be especially rich in in-between states - the intersensory, the metamodal -states for which we have no common language.

Photo: Neville Elder/CORBIS
Dr Sacks 'Can an image be built using nonvisual information?'

If we are sighted, we build our own images, using our eyes, our visual information, so instantly and seamlessly that it seems to us we are experiencing "reality" itself. One may need to see people who are colour-blind, or motion-blind, who have lost certain cerebral visual capacities from cerebral injury,to realise the enormous synthesis, the dozens of subsystems involved in the subjectively simple act of seeing. But can a visual image be built using nonvisual information - information conveyed by the other senses, by memory, or by verbal description?

There has been much recent work on the neural bases of visual imagery, and it is now generally accepted that visual imagery activates the cortex in a similar way, and with almost the same intensity, as visual perception itself. And yet studies on the effects of blindness on the human cortex have shown that functional changes may start to occur in a few days, and can become profound as the days stretch into months or years.

Torey, who is well aware of all this research, attributes Hull's loss of visual imagery and memory to the fact that he did not struggle to maintain it, to heighten and systematise and use it, as Torey himself did. Perhaps Torey was able to stave off an otherwise inevitable loss of neuronal function in the visual cortex; but perhaps, again, such neural degeneration is quite variable, irrespective of whether or not there is conscious visualisation.

But what if their differences reflect an underlying predisposition independent of blindness? What of visual imagery in the sighted? I first became conscious that there could be huge variations in visual imagery and visual memory when I was 14 or so. My mother was a surgeon and comparative anatomist, and I had brought her a lizard's skeleton from school. She gazed at this intently for a minute, turning it round in her hands, then put it down and without looking at it again did a number of drawings of it, rotating it mentally by 30 degrees each time, so that she produced a series, the last drawing exactly the same as the first.I could not imagine how she had done this, and when she said that she could "see" the skeleton in her mind just as clearly and vividly as if she were looking at it, and that she simply rotated the image through a twelfth of a circle each time, I felt bewildered, and very stupid. I could hardly see anything with my mind's eye at most, faint, evanescent images over which I had no control.

I was, however, to get a vivid idea of what mental imagery could be like when, during the 1960s,I had a period of experimenting with large doses of amphetamines. These can produce striking perceptual changes, inducing dramatic enhancements of visual imagery and memory. For a period of two weeks or so, I found that I could do the most accurate anatomical drawings. I could mentally project the image onto the paper before me and trace its outlines with a pencil. But when the amphetamine-induced state faded, after a couple of weeks, I could no longer visualise, no longer project images, no longer draw nor have I been able to do so in the decades since.

A few months ago, at a medical conference in Boston, I spoke of Torey's and Hull's experiences of blindness. Alter my talk,a man came up to me and asked how well, in my estimation, sighted people could function if they had no visual imagery. He went on to say that he had no visual imagery whatever, at least none that he could deliberately evoke, and that no one else in his family had any either.
"And what do you do?" I asked him.
"I am a surgeon," he replied. "A vascular surgeon. An anatomist, too."
But how, I asked him, did he recognise what he was seeing? "It's not a problem," he answered. "I guess there must be representations or models in the brain that get matched up with what I am seeing and doing. But they are not conscious. I cannot evoke them."

So is Torey's greatly developed visual imagery not as indispensable as he takes it to be? Might he have done everything he did, from carpentry, to roof repair to making a model of the mind, without any conscious imagery at all?
When I talk to people, blind or sighted, or when I try to think of my own internal representations, I find myself uncertain whether words symbols and images of various types are the primary tools of thought or whether there are forms of thought antecedent to all of these, forms of thought essentially amodal. Psychologists have sometimes spoken of "interlingua" or "mentalese", which they conceive to be the brain's own language, and Lev Vygotsky, the great Russian psychologist, used to speak of "thinking in pure meanings". I cannot decide whether this is nonsense or profound truth - it is the sort of reef I end up on when, I think about thinking.

Simple visual imagery may suffice for the design of a screw, an engine or a surgical operation, and it may be relatively easy to model these essentially reproductive forms of imagery or to simulate them by constructing video games or virtual realities of various sorts. Such powers may be invaluable, but there is something passive and mechanical and impersonal about them which makes them utterly different from the higher and more intimate powers of the imagination, where there is a continual struggle for concepts and form and meaning, calling upon all the powers of the self. Imagination dissolves and transforms, unifies and creates, while drawing upon the "lower" powers of memory and association. It is by such imagination, such "vision", that we create or construct our individual worlds.

At this level, one can no longer say of one's mental landscapes what is visual, what is auditory, what is image, what is language, what is intellectual, what is emotional - they are all fused together and imbued with our own individual perspectives and values. Such a unified vision shines out from Hull's memoir no less than from Torey's, despite the fact that one has become "nonvisual" and the other "hypervisual". What seems at first to so decisive a difference between the two men is finally, a radical one, so far as personal development and sensibility go. Even though the paths they have followed might seem irreconcilable both men have "used" blindness to release their own creative capacities and emotional selves, and both have achieves a rich and full realisation of their own individual worlds.

© Oliver Sacks. This is an extract from an article first published in The New Yorker, For more details, visit www.oliversacks.com

Learning to See Requires More Than Just Eyesight
Although most people take it for granted, learning how to see is a very difficult task. An intriguing case study published in the September issue of Nature Neuroscience describes a man's recovery from 40 years of blindness and should help scientists better understand how the human visual system functions.

Ione Fine of the University of California at San Diego and her colleagues followed Michael May, a 43-year-old man who had been blind since the age of three and a half, as he recovered from experimental stem-cell surgery. The procedure restored sight to his right eye in March of 2000. Ever since, he has been struggling to adapt to a viewable world, a common problem for people who have regained their sense of vision after years of blindness. May finds it particularly difficult to interpret faces and facial expressions--during testing, he could correctly identify a face as male or female only 70 percent of the time, and expressions as happy, neutral or sad 61 percent of the time. In addition, seeing only the face of his own wife is still not enough for him to identify her, and he relies on clues such as hair length or gait to help him recognize people.

To determine what causes these difficulties, the scientists used functional magnetic resonance imaging (fMRi) to track activity in May's brain as he processed the world around him. Although May's ability to perceive simple forms, colors and motion is essentially normal, the investigators found that when he looks at faces or three-dimensional objects, the brain region active in sighted people during identification is not utilized. This suggests that different parts of the visual system develop at different times, the authors note, with motion processing being more hard-wired and forming very early in life. "The old idea that there is one picture of the world on the surface of the visual cortex is far too simple," remarks study co-author Donald I. A. MacLeod of the University of California at San Diego. "In fact, we probably have a couple dozen maps, each representing a different mode for sensing and taking in our environment." As for May, he is slowly coming to terms with his sight. "The difference between today and two years ago is that I can better guess at what I am seeing," he says. "What is the same is that I am still guessing." --Sarah Graham [Scientific American August 25, 2003 ]





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