Sometimes his descriptions feel comical, but the condition is devastating. "I am thrown particularly when I see people out of context, even if I have been with them five minutes before. This happened one morning just after my appointment with my psychiatrist (I had been seeing him twice weekly for several years at this point). A few minutes after I left his office, a soberly dressed man greeted me in the lobby of the building. I was puzzled as to why this stranger seem to know me, until the doorman addressed him by name - it was, of course, my own analyst."
The deficit is so specific that he is better at recognizing his neighbours' dogs than the neighbours themselves. On several occasions, he apologized for almost bumping into a large bearded man, only to realize that "that large bearded man was myself in the mirror." Once, grooming himself in the reflection of a restaurant window, he realized he was not looking at his reflection of himself self-grooming, but at a man looking at him oddly. Imagine the challenge posed the time he met another face-blind colleague for the first time in a restaurant.
Two per cent of the population have this poorly understood disorder. Needless to say, face-blindness makes a child's life at school very problematic, and one can imagine the teasing, not to mention all the armchair psychiatry people with rare conditions must endure. "I think that a significant part of what is variously called my 'shyness,' my 'reclusiveness,' my 'social ineptutude,' my 'eccentricity,' even my 'Asperger's syndrome,' is a consequence and a misinterpretation of my difficulty recognizing faces," Sacks writes.
In 2005, while at the movies, Sacks began to see a burst of spectral colours and noticed a blind spot within the flare. His doctor discovered a malignant melanoma in Sacks's right eye on his retina a millimetre from where central vision is processed. To avoid removing it (Sacks's left eye was already damaged from a blow in youth), his doctor fashioned a radioactive plaque, which he surgically inserted into the eye to kill the tumour. In the recovery room, the doctor asked his groggy patient if he knew where he was. He should have known better. Immediately Sacks (whose autobiography is subtitled Memories of a Chemical Boyhood) found himself saying that he is "in the recovery room," and he just had attached to his eye "a plaque containing radionioiodine (I-125, to be precise). … I was sorry it was not radioactive ruthenium instead of iodine (I have a thing for the platinum metals) but that 125, at least, was memorable for being the smallest number that was the sum of two squares in two different ways." Sacks, his uncommon ardour for the periodic table renewed, had been recalled to life.
The tumour and the treatment destroy enough of his retina to create a circular blind spot in his right eye that he calls "bagel vision." A flock of birds flies by, disappears into the blind spot, only to re-emerge on the other side. But this visual hole is not empty. It is a window filled with involuntary images: faces, figures, landscapes. With the loss of central vision, Sacks begins having hallucinations, which he thinks "show me the background activity, the idling of my visual system." Hallucinations may also occur because his visual cortex, platform for his mind's eye, is no longer receiving normal amounts of input from his retina, and is becoming neuroplastically altered and supersensitive.
Often, his blind spot "fills in" what is missing. If he is looking at a pattern, and part of it disappears into his blind spot, his brain soon creates that pattern in the hole. (All our blind spots do this, which is why we don't know we have them; we are blind to our blind spots.) At Times Square, Sacks begins to play with his blind spot, seeing how far it will go "filling in" patterns. He speculates that the visual cortex is not so much a duplicating device as "an averaging device, capable of sampling what was presented to it and making a statistically plausible … representation of it." By casting his blind spot on his foot, his brain slowly fills the emptiness with a phantom foot, airier than his "normal" foot, but complete with toes.