If the connective tissue between your two brain hemispheres is severed, the two halves of your brain can't talk to each other.
When this happens, a second personality emerges for the right hemisphere, which doesn't have language but can roughly understand and answer things.
So for example, someone who was religious might have a right hemisphere that's atheistic. Or doesn't like the same things, etc.
One of the questions we might ponder is where this other personality comes from. Is it that in a sudden void of consciousness a new personality develops?
Or are we, with connected brain hemispheres, not actually a single persona at all, but more like the dogs in a trenchcoat looking like a whole person?
Is the 'you' reading this right now just the personality that's been on top for all this time, while there's other personas kept within you watching powerless and yearning for their turn in control? Each time you listen to your favorite song which maybe they have grown to hate, is a part of you screaming and you just can't hear them?
My understanding is that each half of you becomes an independent system. Your right half controlled and perceived by the left brain. And that experiments that hid the left hand from the right, they could prompt both sides to draw something and you’d get two distinct responses.
I suppose you adapt, as you don't have an alternative nor a frame of reference of what "normal" is?
Like people born without a limb, or those who discover they're double-jointed or hyper-extensive/-flexible when their classmates react at their ability to touch their thumb to their wrist.
I tend to envisage my mindscape as an orchestra. My consciousness is a fictitious conductor. It doesn't exist, but the lie that it does makes it easier to coordinate things between the instruments. In some manner, by acting on that lie, it is no longer a lie.
In this analogy, when the brain hemispheres are separated, then the orchestra is split in 2. Both develop a conductor, to try and remain functional. Neither conductor is the original me, but neither is not me, at the same time. It would be unpleasant for the variant left unable to communicate however.
I've actually experienced something that felt close to this before. A combination of sensory overload, and panic attack. My mind momentarily became completely discordant. As it sorted itself out, my consciousness reasserted itself in several different loci. In effect, my orchestra had 3 different conductors. It took almost a minute for them to stop pulling against each other and meld into 1 again. I have memories of all 3 sides in the 'battle'.
99% of my mind is emotional or monkey logic. Getting it to accept logic is like trying to tame a bunch of cats. It works, so long as you can feed them enough dopamine. Fail, and they'll want to eat your face.
It’s fast vs slow brain (there is a scientific term for it, don’t remember right now). Fast brain is what kept us alive. What’s that? Tiger! What’s that? Bear! Immediate fight/flight/fornicate decision tree.
I know a person who is about to have a corpus callusotomy procedure which is where the halves of the brain are divided surgically, in her case to stop seizures. She is globally delayed and I wonder now what she'll be like afterwards.
I think this might be the inspiration for the ravens in Adrian Tchaikovsky's Children of Memory (3rd book in the Children of Time series).
Minor spoilers:
Basically, the series takes place long after human society terraformed a bunch of planets and collapsed, and the main characters rediscover one of these planets which is populated by evolved ravens that have seemingly created a society but no one can tell if they are sentient or just mimicking everything. The ravens evolved to form pair bonds between two different types: one raven in the pair hyper-focuses on all new information and obsessively catalogs it, while the other raven obsesses over finding patterns in the collected data and preforms the executive functions and decision making. Neither raven in the pair is truly sentient on their own, but together they produce either consciousness or a fake so convincing no one can tell the difference.
They even ask the ravens if they are sentient and they conclude that they aren't, and that no one else is either, because of this exact reason; everyone's just components in a system that is hallucinating it's real.
theres a video somewhere of a dude like that where his halves would make shit up independently of eachother on the fly and he was unaware of it. really interesting stuff
Yeah, this is a phenomenon called 'confabulation.' You see it with stroke patients too. There's some who feel like it's a more accurate term than 'hallucinations' for when LLMs make shit up these days too.