One Head, Two Brains: The origins of split-brain research (2015)
73 comments
·February 19, 2025zonkerdonker
The confabulation to justify picking out related images that the left brain never observed (chicken and snow shovel in the article) reminds me profoundly of the confident slop produced by LLMs. Make you wonder if llms might be one half of the "brain" of a true AGI
MathMonkeyMan
That's a theme in the novel "Neuromancer".
codr7
It certainly looks like what LLMs are doing is one aspect of what a brain is doing.
ggm
Key point here is "looks like" I suggest if you want to argue this further to invest the time asking Brain Scientists what they think. Not AI scientists but people who actually work in cognition.
(Not a brain scientist btw)
jjtheblunt
along those lines, maybe dreaming is piecing together new adventures imagined from snippets of reality.
encipriano
Those videos about ai making up a game after having watched countless hours of streaming is fucked up. It looks completely how dreams do
danielmarkbruce
confident slop.
Lerc
The confidence seems to be an artifact of fine tuning. The first instruction trained models were given data sets with answers to questions but generally omitted non answers to things the model didn't know.
Later research showed that models know that they don't know certain pieces of information, but the fine tuning constraint of providing answers did not give them the ability to express that they didn't know.
Asking the model questions against known information can produce a correct/incorrect map detailing a sample of facts that the model knows and does not know. Fine tuning a model to say "I don't know" in response to the those questions where it was incorrect can allow it to generalise the concept to its internal concept of unknown.
It is good to keep in mind that the models we have been playing with are just the first ones to appear. GPT 3.5 is like the Atari 2600. You can get it provide a limited experience for what you want and its cool that you can do it at all, but it is fundamentally limited and far from an ideal solution. I see the current proliferation of models to be like the Cambrian explosion of early 8 bit home computers. Exciting and interesting technology which can be used for real world purposes, but you still have to operate with the knowledge of the limitations forefront in your mind and tailor tasks to allow them to perform the bits they are good at. I have no-idea of the timeframe, but there is plenty more to come. There have been a lot of advances revealed in papers. A huge number of those advances have not yet coalesced into shipping models. When models cost millions to train you want to be using a set of enhancements that play nicely together. Some features will be mutually exclusive. By the time you have analysed the options to find an optimal combination, a whole lot of new papers will be suggesting more options.
We have not yet got the thing for AI that Unix was for computers. We are just now exposing people to the problems that drives the need to create such a thing.
nuancebydefault
I believe most confident statements people make, are established the same way. There are some anchor points (inputs and vivid memories) and some part of the brain in some stochastic way dreams up connections. Then we convince ourselves that the connections are correct, just because they match some earlier seen pattern or way of reasoning.
zdragnar
The basis of human irrationality is not tied to the basis of LLM irrationality.
LLMs don't get to make value judgements, because they don't "understand". They predict the subsequent points of a pattern given a starting point.
Humans do that, but they also jade their perception with emotive ethics, desires, optimism and pessimism.
It is impossible to say that two humans with the exact same experience would always come to the same conclusion, because two humans will never have the exact same experience. Inputs include emotional state triggered by hormones, physical or mental stress, and so forth, which are often not immediately relevant to any particular decision, but carried over from prior states and biological processes.
GMoromisato
I always thought it was interesting that the human brain grew relatively quickly in evolutionary history. 3 million years ago, our ancestors had a 400 cc brain. 2.5 million years later, it was 1,400 ccs--more than 3 times larger.
That implies to me that a larger brain immediately benefited our ancestors. That is, going from 400 to 410 ccs had evolutionary advantage and so did 410 to 420, etc.
That implies that once the brain architecture was set, you could increase intelligence through scale.
I bet there are some parallels to current AI there.
marshmellman
This comment reminded me of "A Thousand Brains: A New Theory of Intelligence" by Jeff Hawkins, which explores this. To Hawkins, the brain's relatively fast evolution implies there's a general-purpose "compute" unit that, once it evolved once, could proliferate without novel evolutionary design. He claims this unit is the brain's cortical column, and provides a lot of interesting evidence and claims that I no longer remember :)
GonzoBytes
All of this is way above my paygrade, however.. There exists this work by Julian Jaynes called The Origin of Consciousness in the Breakdown of the Bicameral Mind: https://ia802907.us.archive.org/32/items/The_Origin_Of_Consc...
Seems pertinent, and now I will try to read it again. Perhaps it will be useful for reference by others.
titaniumtown
Its a very interesting theory, either he's a genius or the theory is completely insane. I cannot decide which one.
rep_lodsb
>Miller’s study uses a test called the “trait-judgment task”: A trait like happy or sad flashes on a screen, and research subjects indicate whether the trait describes them. Miller has slightly modified this task for his split-brain patients—in his experiments, he flashes the trait on a screen straight in front of the subject’s gaze, so that both the left and right hemispheres process the information. Then, he quickly flashes the words “me” and “not me” to one side of the subject’s gaze—so that they’re processed only by one hemisphere—and the subject is instructed to point at the trait on the screen when Miller flashes the appropriate descriptor.
Seems to me (not a neuroscientist) like there's a flaw in that experiment: how would the right hemisphere understand the meaning of the words, if language is only processed by the left? I also recall reading that the more "primitive" parts of our brains don't have a concept of negation.
But maybe they have been considering this and it's no issue?
nuancebydefault
The fact that the explaining part of the brain fills in any blanks in a creative manner (you need the shovel to clean the chicken shed), reminds me to some replies of LLMs.
I once provided an LLM the riddle of the goat, cabbage and wolf, and changed the rules a bit. I prompted that the wolf was allergic to goats (and hence would not eat them). Still the llm insisted on not leaving them together on the same river bank, because the wolf would otherwise sneeze and scare the goat away.
My conclusion was that the llm solved the riddle using prior knowledge plus creativity, instead of clever reasoning.
drupe
If one is interested in hemisphere theory, including psychological and philosophical implications, make sure to check out the work of Ian McGilchrist:
teddyh
Related: You Are Two by GCP Grey: <https://www.youtube.com/watch?v=wfYbgdo8e-8>
LoganDark
i haven't had any split brain operation done or anything but my personal experience as someone with dissociative identity disorder is that i can usually tell which parts are more left or right brained based on how they react to everyday events
for our particular brain , the logical ones usually have immediate reactions that suck (like borderline personality disorder) and the emotional ones tend to have mish mash wordses feelings
(idk how to write that it's like words-es, the s at the end is very gender for emotional feelings words so all of them tend to have it)
Hacker_Yogi
I disagree with Steven Pinker’s claim that consciousness arises from the brain.
This perspective fails to establish that the brain produces consciousness, as it relies on the mistaken assumption that "mind" and "consciousness" are interchangeable. While brain activity may influence the mind, consciousness itself could be a more fundamental aspect of reality. Rather than generating consciousness, the brain might function like a radio, merely receiving and processing information from an all-pervasive field of consciousness.
In this view, a split-brain condition would not create two separate consciousnesses but instead allow access to two distinct streams of an already-existing, universal consciousness.
jstanley
If consciousness doesn't arise from the brain, it seems to be suspiciously well correlated with the brain.
I think consciousness arises from the brain.
MailleQuiMaille
"If the music I dance to doesn't arise from the radio, it seems to be suspiciously well correlated with the radio.
I think the music I dance arises from the radio."
jstanley
Postulate 1: The music is created by the radio in the form of sound waves, the end.
Postulate 2: The music was played by a band in the form of sound waves, some time in the past. The band recorded their music on to some storage medium so that it could be transmitted to the future. In the present, the storage medium is connected up to a piece of equipment that turns the recorded signal into some invisible power transmission that spreads throughout space in a way you can't experience directly with any of your natural senses. The radio however can sense these invisible power transmissions and can turn them back into audio that sounds like what the band played in the past. So we're saying that it is possible to create music in the form of sound waves (that's what the band did), and it is possible for the radio to output sound waves that sound like music (that's what the radio does), but the radio is curiously not the thing that is producing music and instead we have an enormous system of technology transmitting the music across space and time.
You'd need an awful lot of evidence to convince me that postulate 2 is true and postulate 1 is false.
On the one hand you have "consciousness can be created, and it is created by the brain". On the other hand you have "consciousness can be created, and it is created somewhere, but it's not created by the brain, instead it is created somewhere else and there is a system of consciousness transmission that gets it into the brain".
There's just no reason to prefer the second explanation. It is a more complicated story.
kulahan
Note that in this scenario, we’ve never even heard of radio stations or radio waves before.
dbtc
Well, it must all come from a singularity some time before the Big Bang.
Yet, when I turn the radio on, music really does seem to come out of it.
And when I turn the radio off, the music stops (for me, but not for you).
Without the radio there is no sound, but the radio needs a signal.
Does the radio make the music? Quite an interesting metaphor.
selcuka
> I think consciousness arises from the brain.
I tend to agree, but it doesn't fully explain Benj Hellie's vertiginous question [1]. Everyone seems to have brains, but for some reason only I am me.
If we were able to make an atom-by-atom accurate replica of your brain (and optionally your body, too), with all the memories intact, would you suddenly start seeing the world from two different pair of eyes at the same time? If no, why? What would make you (the original) different from your replica?
jstanley
I feel like this is just a totally stupid question.
The brain has inputs, internal processing, and outputs. The conscious experience happens within the internal processing.
If you make a second copy, then that second copy will also have conscious experience, but it won't share any inputs or outputs or internal state with the first copy.
If you were to duplicate your computer, would the second computer share a filesystem with the first one? No. It would have a copy of a snapshot-in-time of the first computer's filesystem, but henceforth they are different computers, each with their own internal state.
You could argue that there are ways to do it which make it unclear which is the "original" computer and which is the "copy". That's fine, that doesn't matter. They both have the same history up to the branching point, and then they diverge. I don't see the problem.
trescenzi
I don’t understand how this refutes physicalism. Only my eyes are hooked up to my brain. If you duplicate the whole system there would be a duplicate that would begin experiencing its own version of reality.
layer8
> What would make you (the original) different from your replica?
You’d be in two different locations, have independent experiences, and your world lines would quickly diverge. Both of you would remember a common past.
How do you know when you wake up in the morning that you are the same “I” as you remember from the previous day? Who isn’t to say that the universe didn’t multiply while you were asleep, and now there are two or more of you waking up?
(You don’t actually need to go to sleep to do this: https://cheapuniverses.com/)
card_zero
Yes, the two of you would see through two pairs of eyes, independently.
Both of you would be you, and you two would function separately, occupy separate spaces, and diverge slightly in ways that would only rarely make a difference to your personality.
But that's not the vertiginous question, which is "why am I me". I've wondered that before. However, it is nonsense. Naturally a person is that person, not some other person (and a tree is a tree, not some other tree). There's nothing strange about this. Why would it be otherwise? So the urge to ask the question really reveals some deep-seated misconception, or some other question that actually makes sense, and I wonder what that is.
peterlada
It would be a fork. Identical experience until that point but bifurcated from the point of fork since it no longer occupies the same physical space
spiderfarmer
New commits.
kerblang
It's not Steven Pinker's claim alone. Gazzaniga agrees, I think, and I know of one other prominent neuroscientist but don't remember his name. Pinker is "just" a psychologist.
(Edit: Michael Graziano is who I was trying to remember - he uses the words "schematic" and "model")
Your view is called "pan-psychism". It's interesting, but there isn't anything that makes it necessary. Everything we're finding out is that most or all thinking happens outside of consciousness, and the results bubble up into it as perception. Consciousness does seem to be universal within the brain, though.
I find pan-psychism interesting just because of its popularity - people want something spiritual, knowingly or not. I would advise not to insist that consciousness==soul, however, as neuroscience seems to be rapidly converging on a more mundane view of consciousness. It's best to think of one's "true" self according to the maxim that there is much more to you than meets the mind's eye.
codr7
Or, people are spiritual, and realize it to different degrees. It's very easy to get confused about what we know and don't know on these subjects.
layer8
This would imply that the behavior of elementary particles in the brain (which ultimately cause our observable behavior via nerve signals and muscle movements, including the texts we are typing or dictating here) differs from the one predicted by the known physical laws. That’s difficult to reconcile with the well-confirmed fundamental physical theories, and one has to wonder why nobody tries to experimentally demonstrate such known-physical-laws-contradicting behavior. It would be worth at least one Nobel Prize.
Secondly, it wouldn’t really explain anything. The “consciousness field” would presumably obey some kind of natural laws like the known fields do, but the subjective experience of consciousness would remain as mysterious as before (for those who do find it mysterious).
at_a_remove
I cannot see how one might perform an experiment to determine which concept is correct. As with most things which are unfalsifiable, the idea can be amusing for a bit but is ultimately not useful to the extent that you can do anything about it. You cannot serve tea from Russell's Teapot.
cognaitiv
If the brain is a receiver, information transfer could happen non-locally and the tea might be telepathy, precognition, or remote viewing. In the split brain example, demonstrating an ability to coordinate between hemispheres in ways not predicted by neural separation might challenge the physical origin of consciousness as with the chicken and shovel anecdote.
Experiments demonstrating an external source of consciousness would be very interesting.
Not a teapot in this case!
at_a_remove
Ah, no.
Suppose you do all kinds of studies and not show any telepathy, precog, or remote viewing. You could still say that the brain was only a receiver. None of that would disprove the "brain-as-consciousness-receiver" concept, you would just say that, I guess it is one way, no telepathy.
It's not disprovable. And so, kind of boring.
cognaitiv
Or communicate telepathically with dogs.
antonkar
Yep, some unfinished philosophy if you're into it: you can imagine that our universe at a moment of time has is just a giant geometric shape, then at the next moment the universe somehow changes into the this new shape. How does this change happen? Some believe it's a computation according to a rule/s, some that it's not a discrete change but a continuous equation that changed the shape of the universe from one to another. Basically you can imagine the whole universe as a long-exposure photography in 3d and then there is some process that "forgets" almost all of it leaving only slim slices of geometry and changing from one slice into another. This forgetting of the current slice and "recalling" the next, is consciousness, the time-like process. And it looks like the Big Bang was like matter converted to energy (or "space converted to time") process. The final falling into a giant black hole will be the reverse: energy converted to matter (or "time converted to space"). Some say electrons are like small black holes, so we potentially experience the infinitesimal qualia of coming into existence and coming out of existence, because we are sufficiently "time-like" and not too much "space-like". I'll soon write a blog post ;)
EMM_386
I've had numberous LLMs tell me that humans are conscious because we are like radio receivers, picking up a single consciousness field of the universe itself.
So that's very interesting that you mention that.
actionfromafar
Descartes was pretty much on the same page.
morkalork
This is dualism, no.
Barrin92
It's not a dualism at all. What the OP is proposing is similar to Spinoza (probably the most hardcore monist to ever exist), where mind is a fundamental property of the universe (in fact, there's only one mind) and each individual person is a 'mode' of it.
It's effectively akin to talking about mass. Despite the fact that mass is observable as a distinct phenomenon in any object, it's obviously not accurate to say that you "produce mass" or that it's "your mass" in some private, ontologically separated way, it just appears that way, by definition if we look at particular manifestations of it.
0x1ceb00da
Looks like this was one of the inspirations behind severance.
Telemakhos
It's certainly an inspiration for the Zizian cult, a group of vegan computer programmers currently being investigated by US authorities for a string of murders across the US. [0, 1]
> LaSota believed that humans have two minds, a left and right hemisphere, and each hemisphere can be good or evil, according to posts on her blog. Eventually, LaSota came to believe that only very few people — she among them — are double good. [1]
[0] https://www.usatoday.com/story/news/nation/2025/02/19/zizian... [1] https://www.nbcnews.com/news/us-news/german-math-genius-get-...
https://web.archive.org/web/20241228215151/https://www.theat...
https://archive.ph/gJ32A