hen you touch a hot stove, your hand jerks back well before your conscious mind is aware of the heat. You've exhibited inhumanly fast reflexes, because in fact this movement is not generated by the human part of your brain—the cerebral cortex, where your consciousness and intellect reside—but from the more primitive brain stem, which you inherit from your earliest vertebrate ancestors.
In Fox's new movie Daredevil, based on the superhero created by Marvel Comics' Bill Everett and Stan Lee in 1964, mild-mannered attorney Matt Murdock also exhibits inhumanly fast reflexes, and a strange awareness of the objects and people and movements around him, despite being completely blind. Hogwash? Not necessarily, because the brain stem receives and interprets other sensations as well, and is capable of seizing control of our muscles to ward off danger before we even know it's happening.
It is commonly noted that blind people's hearing and other senses are more acute than sighted people's, and there is experimental as well as anecdotal evidence to support this. In cases where the visual cortex—the brain's image processing center—remains active, the skin itself may be recruited as a sort of thermal imaging system, facilitating such surprising activities as blind skiing and blind karate. Still, even the most generous among us will note that the very best skiers and kickboxers are never blind. Their senses compensate, but cannot completely fill the awareness gap.
But this may have a lot to do with the kind of blindness these athletes suffer. Worldwide, the most common forms of blindness are cataracts (a cloudy film over the surface of the eye), diabetic retinopathy (bursting of abnormal blood vessels), glaucoma (increased pressure inside the eyeball), macular degeneration (a degrading of the retina) and retinitis pigmentosa (a buildup of opaque pigments). These afflictions, however debilitating, are usually a far cry from total blindness, in which no visual information reaches the cerebral cortex at all. Total blindness may result from damage to the eyes, the optic nerves or the visual cortex itself.
Damage to other parts of the brain can result in exotic visual impairments, such as agnosia, in which the sufferer can see and describe objects or faces perfectly, but cannot identify what they are. The cartoon character Mr. Magoo is apparently an agnosia sufferer, as is Oliver Sacks' real-life "man who mistook his wife for a hat." There are no agnosic superheroes that I'm aware of, but there are other, stranger forms of blindness to consider.
Professional athletes "just see it"
Surprisingly, the visual cortex is not located near the eyes at all. Instead, it's at the very back of the skull, so the optic nerves have to run all the way through the brain in order to reach it. And once the images are processed, the information has to travel all the way forward again to reach the conscious mind, which is located in the very front.
Since nerve impulses in the brain propagate at anywhere from 20 to 100 meters per second, it takes at least a thousandth of a second—more typically a hundred times longer—to become consciously aware of something you've seen. Reacting takes much longer, since you've got to analyze what you're seeing, decide what to do about it and then command specific actions from your muscles.
Conscious intelligence is a powerful tool for analyzing the world around us, but in avoiding danger or competing athletically, it can be downright detrimental. When athletes talk about being "in the zone," where their actions flow perfectly and effortlessly, without thought, they're almost certainly describing a mental state where the slow, inefficient, conscious part of the brain has been left out of the loop, and is merely watching and admiring from the neurological sidelines.
What does this have to do with blindness? Well, as it turns out there's an older vision system built into our brains as well—what neurologist V.S. Ramachandran calls the "orienting system"—which bypasses not only the conscious mind, but also the visual cortex, the "limbic system" or primitive mammalian brain, the hindbrain or reptilian brain and even the cerebellum, which we might tactfully refer to as the "fish brain." There are pathways—very ancient but still functional—that connect our eyes directly to that most primitive bit of neurological tissue: the brain stem. And the brain stem, as we've already noted, is really fast.
It also appears to "see" rather well, providing accurate guidance to the motor cortex which controls our muscles, and even to the conscious centers of the frontal lobe. We owe our knowledge of this to an obscure form of blindness known as "blindsight," in which the visual cortex is damaged but the eyes and optic nerves are not. Blindsight sufferers have none of the conscious sensations we associate with sight; they don't perceive shapes or colors, can't sense movement or recognize faces. By their own accounts, they don't see anything at all.
And yet, if you hold a pencil out in front of a blindsight sufferer and ask her to touch the point, she will do it without hesitation. If you ask her to "guess" whether the pencil is oriented vertically or horizontally, she will guess right every time. If you drop her in a room full of chairs and ask her to follow the sound of your voice, she'll deftly avoid every obstacle, protesting all the while that she can't see what she's doing.
Second sight
in the land of the blind
Interestingly, she may admit to "feeling" or "knowing" where the chairs are. Clearly there is information being transmitted, and some kind of subjective sensation associated with it. It just isn't a visual sensation in the normal, conscious sense.
Now, I don't think you'll find a neurologist anywhere who will say that blindsight is superior to normal sight. We have that visual cortex for good reason, because it helps us make sense of our world in a thousand different ways. But in the specific area of reflexes, with no conscious awareness to clutter or slow the perceptions, it isn't difficult to imagine that blindsight victims are "in the zone" all the time. Like the hot-burner reflex, their ducks and dodges come straight from the brain stem, without conscious planning or analysis.
This is an eerie thought for an eerie disorder, and it leads in naturally to the notion that with sufficient confidence and intensive training, the best and fastest of these people might very well become superheroes of a sort, able to dodge any mortal punch or kick and launch an answering blow before the rest of us know what's happening. I've heard no credible reports of any case like this, but then a person with these abilities might prefer to keep mum about it, perhaps displaying them only in the dark, or while disguised.
It's something to keep in mind, anyway, the next time you're thinking of mugging that blind lady, or stealing her handicapped parking space!
Wil McCarthy is a rocket guidance engineer, robot designer, science-fiction author and occasional aquanaut. He has contributed to three interplanetary spacecraft, five communication and weather satellites, a line of landmine-clearing robots and some other "really cool stuff" he can't tell us about. His short fiction has graced the pages of Analog, Asimov's, Wired and other major publications, and his novel-length works include the New York Times notable Bloom and The Collapsium.
