Virtual Limbs: Living with three armsVirtual Reality is just beginning to head down the full body sensation reproduction path. We are at the very early stages of being able to recreate parts of the physical form, entirely in the virtual. This is a concept which is likely to have very a profound effect upon how we deal with the world around us.
At the moment, VR technology in reproducing virtual limbs is limited to a single limb at a time. This is done by mimicking the movements of the user's physical limb by reading the signals sent down the brainstem, translating and implementing them, as opposed to monitoring the movement of the arm and duplicating that. This is both faster than mimicking the movement observationally, and also allows the technique to work if the user has no physical arm to mimic, so long as the brain is capable of controlling one - e.g., quadriplegics, limb amputees.
Better, the virtual limbs of today do not just read signals from the user's nervous system, but can send reply signals back through it as well, to tell the brain the limb has encountered something. For example, that the hand has grasped an object, and can feel it. So long as the proper signals are sent, it does not matter whether there is a physical object there or not, so as far as the brain is concerned, it cannot tell the difference between physical and virtual limbs.
This is of course, only the start. There will come a time in the not so distant future when large areas of the body are being reproduced virtually at a single time, later moving to the entire body. At that point, the process will require some sort of neural blockage to prevent the physical, voluntary muscles from reacting the same way as the virtual muscles. This could be achieved either by blocking out the signal once the computer has detected it, or by transmitting an interference signal into the nervous system so the body does not understand what it is being told to do. Assuming this blockage is in place, we then have a very unique situation.
The human brain is very adaptable. It can adapt itself to new capabilities all throughout life, and, as has been tested on chimpanzees, if you tie in an extra limb, the brain learns to use it as naturally is it would if it had been born with five limbs.
Thus, having five limbs, or a tail, or a pair of wings, or a third eye, or anything you can conceive of, as a fully functional part of your virtual body is quite possible.
What would it be like to have full control of how your body was arranged?
The RP benefits are obvious: - actually BE a centaur, charging across the plains, heading into war. Actually be an old hag of a harpy, flying over the world, or even a fierce dragon, engaged in aerial combat as naturally as you might bike down the road.
But surely it would take hundreds of hours to learn how to use each new limb? Yes, at least if left only to the brain's natural abilities, it likely would.
However, as our understanding of the inner workings of the brain grows, it should be possible to interface 'drivers' with the brain, most likely neural-prosthetic based, in a computer imbedded in the hypothalamus, or, possibly, some means of stimulating new nerve growth in the particular pattern the new limb requires. This could be used to 'teach' the brain how to handle a given new limb or group of organs in a much shorter time frame than would naturally be possible.
In either case, living with three arms would be much the same as living with two, save that you sub-consciously move three hands in to handle a task, rather than two.
The only real worry in this brave new world would have to be phantom limb syndrome. When a virtual limb is removed, would you feel 'pain' from the 'missing' limb?
The obvious answer as your brain would not be capable of telling physical from virtual, is yes, you probably would. Unless, of curse, the 'driver' that interfaces the brain with the limb is also removed. If this is even possible, separating the controls for the limb from the brain would likely remove all evidence of its existence save memory of use, and that would likely go a long way to removing the possibility of pain from it. This solution would work for physical limbs as well, removing pain by removing the sub-conscious brain's knowledge of the existence of the limb.
How this might be done, or whether it is even possible to remove from the brain as easily as you can add to it, is beyond our technical knowledge at the moment. However, if it is possible, it opens up a whole new can of worms. If it is not, the possibilities for virtual limbs are likely limited to forms similar to our natural ones.
Even if this is the case, the scope for this avenue of interface is still tremendous. Being a dog or cat online uses the same limbs after all, just changes their lengths and movements, minor issues comparatively. Furries and Yiffies would be possible, with just the limited version. Gender bending becomes a reality, and it is certainly no stretch to imagine a significant proportion of the population willing to have limbs #5 and #6 created in their minds, and just recoded for different additions .
That pair of wings sounds really nice.