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Yvain comments on Open Thread: February 2010 - Less Wrong
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Fun sneaky confidence exercise (reasons why exercise is fun and sneaky to be revealed later):
Please reply to this comment with your probability level that the "highest" human mental functions, such as reasoning and creative thought, operate solely on a substrate of neurons in the physical brain.
<.05
I am no cognitive scientist, but I believe some of my "thinking" takes place outside of brain (elsewhere in my body) and I am almost certain some of it takes place on my paper and computer.
Speaking of "thinking" with neurons other than those found in the brain, kinesthetic learning gives me pause concerning the sufficiency of cranial preservation in cryonics. How much "index-like" information do we store in the rest of our neurons? Does this vary with one's level of kinesthetic dependence? Would waking up disconnected from the rest of our nervous system (or connected to a "generic" substitute) be merely disorienting, or could it constitute a significant loss of personality/memory? Neuroscientists, help!
When I signed up for cryonics, I opted for whole body preservation, largely because of this concern. But I would imagine that even without the body, you could re-learn how to move and coordinate your actions, although it might take some time. And possibly a SAI could figure out what your body must have been like just from your brain, not sure.
Now recently I have contracted a disease which will kill most of my motor neurons. So the body will be of less value and I may change to just the head.
The way motor neurons work is there is an upper motor neuron (UMN) which descends from the motor cortex of the brain down into the spinal cord; and there it synapses onto a lower motor neuron (LMN) which projects from the spinal cord to the muscle. Just 2 steps. However actually the architecture is more complex, the LMNs receive inputs not only from UMNs but from sensory neurons coming from the body, indirectly through interneurons that are located within the spinal cord. This forms a sort of loop which is responsible for simple reflexes, but also for stable standing, positioning etc. Then there other kinds of neurons that descend from the brain into the spinal cord, including from the limbic system, the center of emotion. For some reason your spinal cord needs to know something about your emotional state in order to do its job, very odd.
Fascinating. Citation?
I'm much less worried by this than I am by the prospect that I'd have to do the same for many of my normal thought patterns due to unforeseen inter-dependencies.
Indeed, that's one of the reasons why I prefer thinking about it solely in terms of stored information: a redundant copy only really constitutes a pointer's worth of information. It's even conceivable that a SAI could reconstruct missing neural information in non-obvious ways, like a few stray frames of video. Not worth betting on, though.
Thanks for the informative reply.
This was the first objection that my neuroscientist friend brought up when I tried to talk to him about (edit:) cryonics. I don't think science knows yet how dependent we are on our peripheral nervous system, but he seemed fairly sure that we are to a nontrivial degree.
As I say to every objection I hear to cryonics at the moment, your neuroscientist friend should write a blog post or some such about his objections - he has a very low bar to clear to write the best informed critique in the world.
(Guessing you mean cryonics - cryogenics is something else though not unrelated)
I'll mention it to him.
(And, yes, oops.)
Voted up and seconded. Yvain, If what you actually mean is "operate solely through physical means contained within the human body or physical means manipulated by interaction with the human body," then I'll up it to whatever number is supposed to be used for, "I'm only leaving room for uncertainty because there's no such thing as certainty." ;-)
As opposed to ...? Ion channels? Quantum phenomena? Multiple interacting brains? Non-neuronal tissue? Neuronal-but-extracranial cells? Soul? Beings outside the observable universe, running the simulator?
What is this belief supposed to be distinguished from?
Well, hormones, and chemicals such as DMT or endocannabinoids etc surely affect the thinking progress. But the phrasing of the question is not really clear to say if you can count these.
Like others, I see some ambiguity here. Let me assume that the substrate includes not just the neurons, but the glial and other support cells and structures; and that there needs to be blood or equivalent to supply fuel, energy and other stuff. Then the question is whether this brain as a physical entity can function as the substrate, by itself, for high level mental functions.
I would give this 95%.
That is low for me, a year ago I would probably have said 98 or 99%. But I have been learning more about the nervous system these past few months. The brain's workings seem sufficiently mysterious and counter-intuitive that I wonder if maybe there is something fundamental we are missing. And I don't mean consciousness at all, I just mean the brain's extraordinary speed and robustness.
I'm at least +70 decibans ("99.99999%") confident that mental states supervene on to physical states. Whether your exact description to do with neurons in the brain completely captures all the physical states I'm less confident of.
EDIT: updated from 30 to 70 decibans: I would more easily be convinced that I had won the lottery than that this wasn't so.
I might be misunderstanding what you mean by 'more easily be convinced', but if the nature of the evidence we'd expect to be doing the convincing is so different in each case, I don't think we can rely on that to tell how much we believe something.
I was much less easily convinced about Many Worlds that I would be that I'd won the lottery, but beforehand I think I'd have put the odds about the same as rolling a six.
Still curious... How about giving us an ETA?
To get nitpicky, the brain is made of both neurons and glial cells - and the glial cells also seem to play a role in cognition.
I am quite comfortable with the idea that I am my brain, that my brain is made of ordinary living matter (atoms making up molecules making up proteins making up cells), that this matter forms specialized structures responsible for cognition, and I would be hugely surprised if given proof that the highest mental functions cannot be explained adequately in terms of that ontology. The strangest alternative I can think of is Penrose's ENM incomputable-quantum-coherence hypothesis and I'd assign less than 5% probability to his thesis being correct.
How does "operate solely on" regard distributed cognition arguments, like "creative thought is created via interaction with the remaining human culture" and "we constantly offload cognitive processes (such as memory) to external substrates (like computers and books)"?
Also, the "highest" human mental functions operate via a number of lower-level processes. Does "solely on human neurons" include e.g. possible quantum phenomena on a low level?
Good points (whether or not they're why the question is "sneaky").
With a straightforward interpretation of your question, I'd answer "95%".
But since you made special mention of being "sneaky", I'll assume you've attempted to trick me into misunderstanding the question, and so I'll lower my probability estimate to 75%, with the missing twenty points accounting for you tricking me by your phrasing of the question.
Commenting before reading other replies---I'm going to give the boring, sneaky reply that the question isn't well-specified enough to have an answer; I'd need to know more about what you mean by something to operate solely on a substrate. I mean, clearly there are a lot of cognitive tasks that most people can only do given a pencil and paper, or a computer ... is that the sneaky part, that we store information in the environment, and therefore we're not solely neurons?
Could you clarify what you mean by operate on? Or is that part of the point?
Using the definition of 'operate on' that I think is most natural, I'd say there is a .05% chance that these functions only operate on (effect) the physical brain. Unless you mean directly, and then I would assign an 80% chance.
Using the definition of 'operating on' meaning 'requiring', I'd say that there is a 90% chance (probability) that only the brain is required for 90% (fraction) of its functioning. The probabilities I assign would fall down dramatically as you try to raise the 2nd 90% (the fraction). So that I would probably only assign a 1% chance that 100% of higher functions require only the brain.
Given the variety of answers here -- further outside what I had considered -- I should qualify that whenever I was thinking of 'beyond the brain' I still meant within the body; like my spinal cord, heart and endocrine system being involved.
"Highest" confidence is 100%, when the brain does not implement any consideration of failure.
Next highest increment is over 99%, I suspect. Call that my guess.
Edit: I'm an idiot - ignore this response. I thought it was asking "what is the highest confidence level that the brain implements in considering the probability of a proposition", which is different and interesting.
I don't think the brain really implements proper probablistic confidence levels.
Probably not, no.
So not the spinal cord, for example?
Around 10%.
90%
I'm writing this comment after coming up with my probability level but before reading anyone else's responses.
Until Yvain's question, I had not put a number on this. I suspect if there were a machine that could measure how confident I "really" am, it would show a higher number.
I spent less than a minute translating from my previous estimate of "highly confident but not certain" to a percentage. Things I considered that made the probability higher:
Things I considered that made the probability lower:
Yvain, are you going to follow up on this now that you seem to have somewhat more time for participation here? ;)
Short answer: I had just read an article on a book called "The Root of Thought" which made it sound like it was making a very convincing case for a lot of higher thought being based in glial cells and not neurons.
It would have been fun and educational to get everyone to say they were 99.999% confident that thought was neural (which I would have done before reading the summary) and then spring the whole glial cell thing on them.
But I ended up not having time to read or even acquire the book, and no one really took the bait anyway. But yeah, "Root of Thought". If any of you have read it, please tell me what you think.
Thanks! I was starting to expect something like that, though in fact I've only recently become aware that the scientific consensus is shifting away from seeing glial cells as more or less just stuffing.
My mom is a neuroscientist and she mentioned that some time ago, I was planning to question her a little bit more about that topic. (Interestingly given her profession, she is vehemently skeptical that AI is at all possible, but that's a story for another day.)
I'd be happy with just an answer to the clarification I've been asking for...
1%. I find the question ambiguous. Glial cells very likely have a major effect (I assume it's not part of the exercise to look it up).
This is discounting blood vessels and other necessary logistics.
Time for the reveal on this one I think!
Still waiting for you to clarify what this belief is supposed to be distinguished from...
I'm going to say 98%, and not account for fun/sneakiness, because I don't know whether you're expecting people to underestimate or overestimate it. And because if the trick is in the wording of the proposition, I don't care enough to try to figure it out.
My answer ranges from arbitrarily close to 0 and arbitrarily close to 1 depending on how I define the terms. The definitions I like have P very high.
One minus epsilon.
Do you mean that for every epsilon greater than 0, your assigned probability is at least one minus epsilon? If so, you might as well just say one, which isn't a probability.
Jargon File on "epsilon".
Given a specific set of inputs/outputs (i.e. the virtual reality of existing as a human in a world with consistent computers, pencils and paper, teachers, students, etc.), and assuming that I intuitively understand what a "substrate of neurons" is, extremely certain (see ciphergoth).
Without a set of inputs or outputs, the question is a tree falling in a forest. A Turing machine doesn't perform computation if it doesn't have inputs.
Discounting the indication of sneakiness, which looks like it would change the probability if properly taken into account: 65% I wouldn't out of hand dismiss the possibility that parts of the physical body other than neurons in the brain are involved. For instance I wouldn't be terribly surprised if sub-vocalization of verbal thoughts played an important (albeit probably not irreplaceable) role. Confidence that no such thing as a metaphysical soul is involved: 99.9%
I'm going to take your question in the simple sense that first occurs to me, which is something like "dualism is false, and mysterious quantum effects are unnecessary. ordinary molecular chemistry only."
In that case, my probability approaches 1 that ordinary molecular chemistry is 100% sufficient to describe a system that implements reasoning and creative thought, and - heck - experiences consciousness. However, I also think that explaining how will require abstractions that are probably not yet well-understood.
Depending on the terms, something near 100% or 0%.
I offload some of my mental functions to the internet. Does that count?