Image by Golan Levin - source: Flickr
Have you ever heard about phantom limbs? It's the widespread phenomenon among people who had one of their limbs amputated, whereby these people have the sensation that the limb is still there. They even sometimes feel pain in these limbs that are long gone, so called phantom limb pains. This is something we can all understand; the brain has built over years a connectome with the limb attached, and that neural structure persists, even after the limb is gone.
But we can turn this around. We can also make the brain incorporate a fake limb as an integral part of our body. I think many, if not, most of you will have heard about the "rubber hand illusion". If not, please watch this short video:
After watching the fake hand and simultaneously feeling your real hand being stroked for a short while, the brain has already made the structural adjustments, through a property we call neuroplasticity, needed to accept the rubber hand as the real hand. This is amazing in its implications.
In addition to hanging on to absent parts of our body, the brain is capable of adopting new parts as our own. This has given birth to the science of cognitive neuroprosthetics; imagine what an extended rubber hand illusion could do for people with prosthetic body-parts? To truly be able to see the prosthetic arm as one's own? But we don't stop there; now that we have advanced virtual reality technology, we can even train the brain to accept an entire virtual body as our own! Movies like Avatar and Ready Player One don't seem so far fetched anymore now, do they?
Experiments have been done to see how far we can take this rubber hand illusion. Subjects were placed on a "multi-stroking machine" while looking at a virtual body, an avatar. The machine stroked the subject on various body parts, synchronized carefully with what the subject saw done to the avatar. After a while the subjects experience a feeling of disembodiment as they start accepting the avatar's body as their own. This even happens on a subconscious level as they observed that the subjects' body temperature dropped significantly during the virtual disembodiment. The audio is very bad, but here's that experiment:
So, what is real? It seems real is whatever my mind tells me is real. But it also seems my mind doesn't always perceives what's real; we don't see with our eyes, we perceive with our minds. And our minds don't passively record reality, instead they actively construct a model of reality, while constantly making predictions about future states of that reality. And that model trails reality by quite some time, at least the part of the model that we're conscious of. Scientists have since long shown that the brain already made a decision what to do, half a second before we are consciously making that decision. This is exactly what heated the fire under the whole discussion about the existence of free will.
Under "normal" circumstances we feel that we are a self in three major ways. First it is in the recognition that we are the cause of the actions and movements of our body. Second is that we feel that we are inside our own bodies. And third is a sense of ownership over our own bodies. This is deeply rooted inside us; in a previous article I discussed the connectome of C. Elegans roundworm. It's a simple creature and has the only brain we have been able to map 100%. Of the 300 or so neurons, one has the simple task of differentiating between "worm" and "not worm", to prevent it from eating it's own tail-end. That could be one of the first beginnings of the complex self-consciousness we have developed ourself. C. Elegans is a common ancestor after all.
The worm won't be fooled by a "rubber worm-tail illusion" though; there's no misdirecting that one neuron. The worm has no "self" and mostly only exists with a very narrow range of experience, if any at all, where we do recognize a "self" as the subject of all the diverse experiences we have and as the physical body that houses the self. But that's where the disturbing overlap takes place; our body is also just a model, part of the constructed reality inside our minds. And our minds can easily be fooled in it's constant efforts to create a coherent view on the world with ourself in it. Ah well, that's also what makes us capable of incredible imagination and using that imagination to leave the real world; like when you're watching a good movie and you look down, only to suddenly realize that all the popcorn is gone...
The above is a redacted version of a post I originally released on Steemit in November 2018
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