There are lots of subtleties in the way Jake Sully’s mind would have to be mapped into the avatar’s brain, beyond the issues of coding, data transfer rates and all the other information-technology stuff we touched on in the last chapter.
An avatar body is more like a Na’vi’s than a human’s. So to run his avatar, Jake, a human being, has to learn how to be a Na’vi.
I find it a lot easier to imagine that I could drive a fully human avatar than that I could drive an avatar of a Na’vi. Or indeed, an avatar of my own little dog.
For one thing, I’m well aware that my dog doesn’t see the world as I do. This is evident when we watch TV, at least on an old analogue set. Such sets present a series of still images quickly enough to fool the human eye into thinking it’s seeing continuous motion. But my dog’s eyes were evolved for a subtly different purpose than mine, and their “flicker-fusion rate” is faster than mine. He can see the individual frames, and indeed the blanks between them, and so to him the TV screen is like a dance floor under a strobe light. That’s why an analogue TV never captures his interest (but digital sets remove the flicker-fusion problem, and the dog is fascinated, at least by programmes featuring other dogs).
If this is a challenge for my little dog and me, who as mammals are pretty close relatives in the grander scheme of Earth’s family of life, it’s going to be ten times more difficult for Jake and his avatar. After all, Jake and the Na’vi are from different worlds altogether.
The sensory functions of Jake and his avatar overlap, but not completely. For example a Na’vi’s sight goes beyond the human range, into the near infrared, to allow night vision. This provides input which has no analogue in the human sensorium. You could imagine transforming the input images somehow so that they map over the human range; it might be like wearing a soldier’s infrared vision enhancer in a combat zone, and having its images superimposed over the visuals in a heads-up display. But enhancements like that would provide an entirely artificial picture, and would be nothing like what the Na’vi actually sees. Jake has to learn to see like a Na’vi, not like a human with enhancing goggles.
What about hearing? Perhaps those mobile Na’vi ears give their hearing a three-dimensional quality like nothing in the human sensorium. There would be no mechanism in Jake’s head to process such information—no analogy in Jake’s sensory world to map onto.
With motor functions it’s a similar picture. It’s easy to imagine Jake’s brain running a fully human avatar. The region of Jake’s brain that “runs” his right hand can be made, through the link, to “run” the avatar’s right hand; there could be a one-to-one mapping between the driver’s brain and the avatar’s body functions.
But there are areas where a Na’vi’s body function doesn’t map perfectly onto a human brain. The most obvious is that prehensile tail. Jake has no subroutines in his head to work a tail (or if he does they are vestigial, relics of very ancient days when human forebears did have tails). More than that, he doesn’t know how it feels to work a tail. Another entirely nonhuman aspect of the Na’vi experience is the neural link to other animals through the queue. No human has ever experienced such a link; we have no neural subroutines in our brains to process the data coming into the avatar’s head from the direhorse or the banshee.
In 1974 an American philosopher called Thomas Nagel published a paper that has become a classic in its field, called “What Is It Like to Be a Bat?” Exploring issues of consciousness and the “mind-body problem”—how mind arises from the machinery of the body—Nagel was attacking what he called a “wave of reductionist euphoria.” Reductionism is the breaking-down of concepts into smaller pieces for the purpose of measurement and understanding. Nagel argued that consciousness must be tied to “the subjective character of experience,” and so, perhaps, can’t be broken down into little bits.
Nagel’s use of a bat as an example is instructive. A bat is a mammal, like me and my little dog, so pretty closely related to us both, but a bat experiences the world entirely differently from us, primarily through its sonar echolocation system. Its brain processes sound inputs into location and distance information. Inside its head, a bat must “see” the world as a kind of shadowy three-dimensional theatre, painted in auditory data.
Nagel argued that it’s impossible for us to imagine how it must be to be a bat. Even imagining a transition from one form to another—to lose your sight, to have leathery wings strapped to your body, to be hooked up to a sonar system—is an artificial exercise. And (though Nagel didn’t take his argument in this direction) the “reductionist” idea that you could brain-scan a bat and download it into a computer store, without it losing its sense of self as a bat, begins to look a bit silly. Maybe we aren’t just abstract information flows. Maybe everything about our cognition is shaped by the way that we’re embedded in our bodies, because that’s the way we apprehend the universe.
To restate Nagel’s question: what is it like to be a Na’vi? The mapping of Jake’s brain to a Na’vi’s body must require a lot of interfacing, beyond the basic spark-by-spark level of neural inputs and outputs, even beyond the higher-level mapping of Na’vi experience to a human mind. Somehow, the governing software must render the sensations of being a Na’vi into forms capable of being comprehended by Jake, at both sensual and inner levels.
However it works, evidently the psionic link does function in giving the driver a fully immersive experience, as we see from the scenes of Jake’s very first linking—his delight in his new body, and in the world he apprehends. And as the movie goes on we see Jake being drawn steadily into the new world at the expense of the old, almost like an addiction to a computer game, until, as he says, the dream of Pandora seems more real than his own humanity.
And ultimately, following the logic of his personal quest, Jake makes the final step: to leave his humanity behind altogether.