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To be energy-efficient, brains predict their perceptions (quantamagazine.org)
357 points by sebg 67 days ago | hide | past | favorite | 155 comments

Classic in marriage counseling. Many fights occur not because of what the other person has said or done, but because what your own brain has added to their behavior. Often, you see what you are most afraid of. Or what you used to experience in childhood. To “see” that your partner here and now is actually completely different takes a lot of energy.

Reminded of these lines from a poem:

We look at the world once, in childhood. The rest is memory.

Try acid.

Enjoy the childlike wonder. Or don’t enjoy, not everything a child perceives is fun.

Would magic mushrooms be fine as well?

Sure would. Both work (partly) by increasing the communication between different parts of your brain. It's why people will "see" things after auditory stimuli, or vice versa.

Changes at this basic level are temporarily re-writing how your neural network connects to itself, which translates to a change in how you perceive the world at the most fundamental level. It is very different from consciously trying to adopt a different perspective, as in that case there is no change to the underlying network processing everything that makes you yourself.

Some people find experiencing this malleability extremely upsetting and disconcerting, as it destroys the idea of your "self" being something concrete. This understanding is the oft-referenced "ego death", and for sure it is both exciting and terrifying.

a lot of people like mushrooms over LSD because “they're natural”, they are poison and can make your stomach ache throughout your first trips until your tolerance builds, this can exacerbate negative aspects of your experience

Acid (LSD) is much stronger in muuuch lower doses and is more of a refined component - its a totally different dose scale. Doesn't mean you wont have a bad trip though, just that your stomach won't hurt lol. Buckle up. Great way to spend 500 years in an afternoon.

For sure, you learn what you live.


Obviously. But can this possibly be turnt off? Maximizing reliability of perception/judgement and minimizing energy efficiency (burn as much calories as possible without moving or any feelable effort) seems right what we need nowadays.

Oh sure it can. Get plenty of sleep. Minimize your ambitions and responsibilities. Eat well. Take walks and naps. Do not rush anything. Do everything “consciously” and being “present”, as the New Age gurus would say. Basically, if your RAM is clear and your CPU is idle, you’ll be more perceptive.

I suspect that’s why some of the self help stuff actually works. It has nothing to do with “the law of attraction” or anything supernatural like that. It’s just that your own state is the biggest filter that determines which “frequencies” out of the spectrum of reality you perceive and which you do not.

The problem is, of course, that the world is wildly interesting. There are so many things we can see and learn and do today. You’d have to say no to all of that to keep your system clean. The very fact that you’re here on Hacker News shows that you’re probably not that kind of person. :) (Me neither.)

That would imply binary controls over both cognitive and metabolic function, so I'm gonna say no. "Maximizing reliability of perception" is also not really a thing, because perception is pretty subjective. And I don't think you actually want to minimize energy efficiency, unless sprinting while doing calculus after 72 hours of no sleep is your hobby?

> And I don't think you actually want to minimize energy efficiency, unless sprinting while doing calculus after 72 hours of no sleep is your hobby?

No, my "hobby" is laying flat and loosing fat (which is done mostly by the brain burning calories AFAIK). I once gained sixpack abs this way. Unfortunately I don't have enough time to lay flat these days so I don't have the six pack any more. I also am very aware of the tricks my brain plays on me all the time and hate that.

Humans don't need to save energy any more. Energy-saving and accumulating features of a human body are an atavism doing obvious harm (e.g. inclining us towards wrong judgement) and no good in today world. We have infinite amount of calories readily available 24x7 all year round. Sugar is dirt-cheap, almost everyone has at least some fat deposits they don't need, don't want and occasionally torture themselves to get rid of.

It would certainly be great if our brains could expend as much energy as physically possible to actually power our perception and thinking rather than save it.

> laying flat and loosing fat [..] I once gained sixpack abs this way

> It would certainly be great if our brains could expend as much energy as physically possible

That's... not how the body works. You should really talk to a med student so you don't make any dangerous health decisions.

Would you give some clue on what do you mean? I didn't use any meth for that if that's what you guessed.

My partner and I strive to at least be aware of it, so we sometimes have exchanges like

“Ok, stop getting on my case about it.”

“What? I didn’t say anything at all!”

“Oh… well, the you in my head was getting on my case about it.”

Awareness helps a lot.

Nonviolent Communication, the concept and the book that teaches it, gives practical guidance on how to avoid falling into this trap. Highly recommended.

Yes and:

- https://dougnoll.com/de-escalate/nonviolent-communication-ba...

> Many people ask me about the difference between Nonviolence Communication basics and the Noll Affect Labeling System. This lengthy article explains those differences. Fundamentally, we peacemakers want to minimize human conflicts, calm people down, solve problems, and make durable agreements for lasting peace. Peacemaking and mediation help achieve these goals. Unfortunately, as will be explained, psychologists, counselors, therapists, peacemakers and mediators have mistakenly tried to create empathy through the use of "I" statements during active listening. "I" statements are important, but not for creating empathy and certainly not for de-escalating anger or other strong emotions. The inappropriate use of "I" statements comes from a misunderstanding of the work of Thomas Gordon, the inventor of active listening, and Marshall Rosenberg, the creator of Nonviolent Communication.

I highly recommend Douglas Noll's book, _De-Escalate_.

holy crap this is a very useful insight for me. Thank you!

THE BIGGEST issue in marriages, no doubt.

And usually the reason of most marriages in the first place. People feel limerence, hallucinate all sorts of fantastic things about each other, themselves and their future and take that seriously.

Easy for what I consider to be mature people.

You have to clear the cache constantly.

You can actually just overwrite the neurons. But it requires multiple exposures to new perspectives.

That’s a great way of phrasing it! The book “Radical Honesty“ shows one way how this can be done.

(Basically, doing one “core dump“ when you begin dating, and then having regular “radical honesty sessions“ where both of you can bring up those apparently “small“ and “unimportant“ thoughts you might have had throughout the week that, if suppressed, can turn into the seeds of resentment.)

It isn't that straightforward for GAN.

Insufficient memory to perform operation. Your brain will go to sleep in 5...4...3...2...1...

Is this a reference to a book or a show? That seems like something I'd really like to read.

I don’t recognize it if so. But it does sound like how my own brain feels when approaching information overload, followed by a power nap.

See my comment above. “Radical Honesty“ by Brad Blanton is what that comment immediately reminded me of.

Related but also not: One of the most interesting aspects about a "shroom" trip is the incredible ability to visualize. Visualizing is something that we all think we can do normally, but if you really try to picture something in your head -- specific faces, the design of a bicycle, the layout of a room -- it's quickly evident that we are actually terrible at it (it's hard to reverse information from that neural network). Even if you're drawing it's often an iterative process where each line drives the next.

Maybe other people are better at it, but when self-interrogating and inspecting one's own vision, it just completely falls apart. https://www.booooooom.com/2016/05/09/bicycles-built-based-on...


I can only speak to personal experience, but under the influence of psilocybin I find that closing my eyes and visualizing complex environments and machines -- of literally inspecting and walking through gearing systems, for instance, and rationalizing their operation -- with complex lighting, etc, leaves me just in awe at the mind's capacity. It literally feels like looking into another universe, the construction of the reality simply too complex to be imagined and visualized.

I've actually felt my head to ensure I'm not overheating, contemplating the process like the mind was a GPU.

> Visualizing is something that we all think we can do normally... we are actually terrible at it

> leaves me just in awe at the mind's capacity

Want a really trippy realization? All you ever see is brain activity! Sounds obvious, but most people haven't really internalized it. That's all regular perception, which feels totally real and solid, is. The psychedelic just gave you a greater ability to volitionally influence the percepts.

> All you ever see is brain activity!

YES. To put it crassly, it's like your brain is The Matrix.

I was driving the other day, thinking about reaction times and had the actual tangible feeling that I was just behind 'reality' because we don't actually see, feel, hear reality we see, hear, feel the brain's interpretation of it, and so it's ever so slightly behind 'actual' (are there variations in processing speed? And how do the fringes of these variations affect one's ability to exist in society?).

We are all living a very recent, rolling memory. Operating system loaded into RAM.

Related to this, I think the phenomenon of "being in the zone" is where the separation between reality and what we perceive of reality seems to get extra narrow (to the point of thinking that there isn't a separation between the two). In times like this, we tend to do things "without thinking" (such as in the case of athletes), but I suspect that we are either processing things (a background level of "thinking") so quickly that our minds can't/don't have time to explicitly form thoughts about reality and respond to these thoughts, so eventually they give up on doing these things during the duration of much of the remaining time in the zone, or so processing things so correctly (matching reality relatively better than in other times/contexts) that it's notable.

Some professionals take issue with this framing, but it's usually referred to in jargon-permitted settings as "controlled hallucinations".

Why do they take issue with it? It seems obviously true?

We've clearly got inputs, outputs, and when working correctly, some signal processing going on in the middle.

For one, the hubris of obviously-uninformed statements such as this one.

But more like: the inputs, processing, and outputs have much more complicated relationships than this causal chain that you have described. Modern neuroscience and research into NCC have shown that the brain, obviously, is not so simple.

Maybe they're the sort of professional who also get tax exemptions on religious grounds

A foolish supposition that draws a pre-supposed (and patently, absurdly false) binary across what people are allowed to believe.

I know there’s little tricks you can play with your visuals/perception of time by looking at clocks and away quickly.

yeah, those color illusions really demonstrate this. like when you stare at a point and the picture changes, the picture looks fully colored but in reality its turned black and white and your brain just hasnt realized it.

This happens to me (almost) every night, before i fall asleep, and for some short time right after I woke up

Amazing state, i love it!

Yes. I was very conscious of this state as a child and less so as an adult but when I am it is peaceful.

I like the way you are thinking here. Speaking of the brain as a neural network, what might be the counterpart of psilocybin in our cs neural networks?

Randomized weight updates?

along with amplifying feedback bleeding into unrelated parameters

> Maybe other people are better at it

The reality is that every individual's ability to visualize exists somewhere on a spectrum between aphantasia (complete inability) and eideticism (photographic memory).

That bicycle experiment is fun, and it certainly shows that most people are very far from the eidetic end of the spectrum.

But it can also (better) be explained by the facts that:

- people generally don't pay very close attention to any particular object, they categorize things and move their attention elsewhere (mostly to higher levels - e.g. the whole environment level)

- most people don't have a whole lot of experience with bicycles and how they work at a detailed mechanical level (anybody that does can draw a bike fairly well, from a technical accuracy perspective)

The ideas in this article are strongly reminiscent of those in Jeff Hawkins' "On Intelligence" (2004).

The idea of the brain operating (at least in part) as a "prediction machine" is certainly not a new one. I'm actually surprised it's taken this long for this sort of experimental confirmation and theory to become more mainstream.

"Being You" by Anil Seth, released last month, is a great primer on predictive processing and its relationship to the science of consciousness. Its a great complement to Hawkins' latest. https://www.amazon.com/dp/B08W2J9WWD

It's been known in many communities, I think.

There's been a number of articles on HN over the years on saccades / visual interpolation.

See: https://www.portsmouthctc.org.uk/a-fighter-pilots-guide-to-s...

For thousands of years:

>The mind has a basic habit, which is to create things. In fact, when the Buddha describes causality, how experiences come about, he says that the power of creation or sankhara—the mental tendency to put things together—actually comes prior to our sensory experience. It’s because the mind is active, actively putting things together, that it knows things.

>The problem is that most of its actions, most of its creations, come out of ignorance, so the kind of knowledge that comes from those creations can be misleading.

The second paragraph is getting off the topic - or is it?

>The idea of the brain operating (at least in part) as a "prediction machine" is certainly not a new one

Yeah, you hit the nail on the head right there! The idea goes back at least as far as Hermann von Helmholtz (19th century).

On any serious discussion of neuroscience, I'd advise to keep Jeff Hawkins out of it. Not only are the ideas he publishes often gross simplifications with little data to back it up (but does wonders as marketing), they were ideas pushed and developed by real working neuroscientists. Just my opinion.

isn't that pretty face value what Numenta's goal is though? They read research papers on neuroscience and try to distill it down to applicable engineering problems for their HTM and see what works.

i can't speak much as to their original research efforts, but i personally appreciate the engineering-research side of what they are doing.

I personally don't mind what his company is doing, but I just don't think his views represent the understandings of my field all that well.

What resource would you recommend for getting an intro to those topics in neuroscience, that provides a better representation?

google scholar

Thought of this as well. Have you read his newer book? I haven't decided if I should pick it up or not.

I have read the book and I really liked the first half, which explains the "thousand brains theory of intelligence". Very inspiring and thought-provoking (at least to me as an interested amateur in this field). The second half, however, would better have been a book of its own. It's about Hawkins' ideas on AGI implications and whatnot, which is quite entertaining but devalues the first half, in a way.

It's alright, I didn't end up finishing it. I really like On Intelligence, wasn't pulled in to finish. Might have been state of mind at the time etc

Oh, he has a newer book! Thank you!

Prediction machines, yet critically, taking actions that pursue states which we are not quite able to predict. https://reader.elsevier.com/reader/sd/pii/S0896627315007679?...

It’s basically how large language models like GTP-3 work. They simply predict the next most probable word and suddenly you can prompt them to give you answers to rather intelligent tasks.

The brain is a prediction machine largely. How is it possible that you can experience a lucid dream where every sensation and interaction is as real as real life? It’s because your consciousness lives inside a simulation. When you’re awake, your brain uses sensory input to populate the simulation. But when you’re asleep it populates it itself. When you’re awake, your brain doesn’t scan every square inch of the real world looking for things to populate the simulation; it scans sparsely looking for key indicators and then guesses the rest. It’s an optimization for time and energy. Most of the things you experience are guesses. And when you’re asleep this guessing is all that you’re seeing. Dreams are just the guessing machine.

There are scattered reports of lucid dreamers who take benzodiazepines. They can’t escape their dreams. They simply wake up into the dream again if they die. Everyone reported it as being terrifying. Some reported that their reality checks stopped working; double taking at a watch didn’t change the position of the hands. The world became frighteningly real. It’s likely that the guessing machine you experience during a normal dream is not operating at full capacity.

It explains everything. How people swear on their life that they saw something, ordinary or extraordinary, that couldn’t be explained by a trick of light on the eyes or anything else. It explains dreams of course and other realistic hallucinations had by schizophrenics or drug users. The simulation doesn’t just deal with the physical world, it deals with abstract things like the “presence” of a person or entity. It’s all haywire simulation.

This idea that synapses are a part of an energy optimization is fascinating. It is widely speculated that inflammation has to do with schizophrenia, and inflammation is also involved in metabolic interference. African sleeping sickness for example is a purely inflammatory disease that causes people to run out of energy and fall asleep. Perhaps schizophrenia is some kind of metabolic knob being turned down by an inflammation signal which then results in the progressive shutting down of synapses as a way to conserve energy…

> There are scattered reports of lucid dreamers who take benzodiazepines. They can’t escape their dreams. They simply wake up into the dream again if they die. Everyone reported it as being terrifying.

I am not a lucid reamer nor to I take benzodiazepines, but I do occasionally have dreams that I suddenly realize are dreams and then wake up into another dream. Occasionally, this too results in my realizing I'm dreaming and waking into another dream, where the pattern repeats at faster and faster pace until I'm just examining the way my bedroom appears in each iteration looking for how it is wrong and trying desperately to wake up for real this time.

I can confirm that it is pretty terrifying. Fortunately for me, I've developed an appreciation of nightmares and actually don't mind it all.

Egon Metzinger, The Ego Tunnel - The Science of the Mind and the Myth of the Self, Basic Books 2009



Ups, of course it's Thomas Metzinger.

Sorry, a momentary lapse of reason.


You wonder if that Batman episode about people not being able to read in their dreams holds up

I was able to read a short sentence from a newspaper in a dream, so it's possible to visualize each character, but then nothing else was happening in my dream, probably that should have kept my mind pretty busy.

I remember reading that and of course one of my dreams had to be about reading something, the letters were huge and gothic.

>Through predictive processing, the brain uses its prior knowledge of the world to make inferences or generate hypotheses about the causes of incoming sensory information.

I wonder if this mechanism is responsible for many shared false memories (or Mandela Effect). As an example, the spelling of the Berenstain Bears is misremembered by many, perhaps because we're so accustomed to seeing the suffix -stein in last names.

For a couple of years I made my living as an audio mastering engineer, which involves making tiny changes at or below the threshold of perception. One of the main ways I set myself up for success was to accept the human perceptual mechanism's propensity for illusion, and then to build systems which helped me avoid being deceived by it.

• An instant level-matched AB switching mechanism for auditioning changes

• Preferring tools which could be checked under optimal perceptual conditions, and choosing to avoid gear which did not lend itself easily to such conditions. This generally meant preferring software plugins and avoiding outboard gear unless the budget was very high (which it rarely was for my clients).

• Isolating changes and amplifying the effect to well above perceptual threshold in order to get an impression of the change before dialing it back down. (This is a standard practice, especially for mix engineers.)

Many audio engineers don't hold the same priorities, especially "audiophile" types those who advertise their "golden ears"[1]. And many customers don't want someone who acknowledges the fallibility of their perceptions. But I was confident that I was absolutely doing my best work and offering the best possible value to my clients.

[1] It's basically impossible to talk intelligently about audio in an open internet forum (including HN) because there will always be a swarm of participants who don't accept the limits of perception and their own propensity for illusion.

> gear which did not lend itself easily to such conditions

could you expand on this a bit? I don't see how software vs hardware could impact this, doesn't it all just go through an amplifier to your headphones at the end?

I built my AB system in software, which allowed me to make a tiny crossfade on switching and avoid a big click. It's well understood that such clicks wreak havoc on your ability to perceive small changes. I didn't have access to an analog version of that at the time.

It was also more difficult to set up and compare multiple "wet" settings for hardware devices, and it was less convenient to "save" settings, take a break and come back with fresh ears (because the studio might be used for something else in the interim.)

It's possible to give yourself optimal conditions with hardware tools, it's just less convenient (and thus more expensive). I believed that giving myself optimal perceptual conditions and an ideal workflow was far more important than gear choice — especially in terms of value, but in my view even in terms of doing my best work in an absolute sense.

One thing ive done with my tiny amateur setup is close my eyes and click the switch a bunch of times, such that I can attempt to discern between two settings but no longer know which is which, and then attempt to discern a difference. The crossfade sounds like a very interesting method although it would prevent the destruction of knowledge for me as (at least I don't know how) you can't randomize it. But maybe my approach is terrible, it's just something I cooked up because I noticed I couldn't tell what anything was doing anymore, it helped make difficult decisions slightly easier.

I would also be interested in hearing about the studio! Was it just a big place that you were renting occasionally, is it possible to rent a real room with a mastering desk? Im still renting so I can't do all those fancy room modifications yet.

Only think I can think of is taking the effect of cables and preamps out of the loops when running through outboard gear?

It's always astounding to me the number of "engineers" who make fantastic claims and have never done an abx. It's nice to know I'm not alone.

Do you give mentorship/lessons?

In my view, understanding the human perceptual mechanism was as essential as understanding how to set up good monitoring to doing my best audio engineering.

I left the audio industry a long time ago. I love music, but I don't love audio engineering enough to sacrifice my life to it — and because there's a tremendous oversupply of labor for art-adjacent professions, that's what it takes.

I really appreciate your comment. (I commented on the parent to share this link, going to share it here too because I think you'll appreciate it as well: https://en.wikipedia.org/wiki/Ideasthesia#Neurophysiology_of... )

> Berenstain Bears

Now that's a weird one, never saw that example before. I'm familiar with the subject ... yet, if you asked me to spell it, it would have been -stein.

Very interesting.

That was probably the example that propelled the phenomenon to mass-consciousness. That and Shazaam were the two people talked about all the time around when the subreddit formed, and Berenstein definitely had a much larger group of people sure they remembered the wrong way being true.

Just this week, I was reading Berenstain Bears books to my daughter, and shocked that it was not Berenstein. I still hear Berenstein in my head. Then I see your comment, which I shall interpret as that I am not misremembering, instead I am in the Truman Show—and some prop guy spelled the title of the new book wrong, and your comment is all part of a rushed coverup.


(Of course, I recognize this as another instance of https://en.wikipedia.org/wiki/Frequency_illusion)

I still refuse to believe ET by Katy Perry always said "different DNA". I distinctly remember it used to say perfect DNA, not different DNA. Or I've lost my mind.

I have Aspergers and suffer from something called closed eye visions. When I close my eyes, mostly at night, I get flashes of images, like faces and people and places. The idea is that the brain is trying to make sense of the random light patterns I am seeing even when my eyes are close. And so it’s hyper predictive. Like others are saying, this is nothing new to me.

Same here. I used to narrate them and make up stories about them to my girlfriend :)

There's also a different TED talk than the one I already linked about your theory which gives a lot of interesting examples[1].

1. https://youtu.be/SgOTaXhbqPQ

I get these too, although I wouldn't describe it as suffering. Sometimes the images are detailed and tangible enough that it feels like looking at a printed photo through my eyelids. When the images are particularly interesting, I like to draw them.

Sometimes mine are horrific though. Like a face in bandages with an eye hanging out. But sometimes they are interesting and nice, like tree tops of a forest.

I've definitely read somewhere else (can't remember where) that the predictive loop is a core learning mechanism. Your brain diffs its prediction against what actually happens, and when there's a big enough difference between prediction and reality, learning occurs (ie your brain tries to change its prediction model so that it can encompass whatever it just perceived in the future).

This article is so fascinating... and it reminds me of one of my favorite topics! I'm excited to share this link:


> Ideasthesia is congruent with the theory of brain functioning known as practopoiesis. According to that theory, concepts are not an emergent property of highly developed, specialized neuronal networks in the brain, as is usually assumed; rather, concepts are proposed to be fundamental to the very adaptive principles by which living systems and the brain operate.

Oh, that's interesting and it lines up with Chomskys ideas that language "surged" as a self soothing mechanism, as a mental scheme where the "individual" can "think words" to self soothe and make sense of its environment , our differences as humans is our capacity to verbalize and structuralize it more easily than other species such as maybe dogs, or zebras

Whales, Elephants and many others can achieve strong degrees of said structuralization and verbalization of the "language" in their minds as well

This TED talk has a great example where the same sound sounds different to you based on what you expect to hear, if you need to prove this to yourself [1]. His thesis is also that the brain is a prediction machine.

1. https://youtu.be/lyu7v7nWzfo?t=365

Here is a sound that sounds like either brainstorm or green needle, depending on which words you focus. Try own word combinations. I have no trouble hearing brain needle or green storm, for example.


That is incredible. Every time I try to hear it one way I do, and then I try and hear it the other way and I do, clear as day. I even started backing up the playback bar and repeating the exact same part of the audio and it's BOTH!

Hmm no matter how hard I try, I can't get storm. Closest I can get is brain needle. It's just too clear to me that there are three syllables, and I can't map storm to the second half.

I had trouble hearing it too, so I closed my eyes to remove the flashing light as input and, I shit you not, just straight up told myself "you will hear brain storm". It was interesting not only in that that worked, but that my perception of the word was so completely different that it sounded nothing like green needle.

And no matter how hard I try, I can't get "needle". There's an "s" sound in there, how does anyone get "needle" out of that? :P

Michael Shermer played Stairway to Heaven backwards and it mostly sounds like gibberish. But when he displays the 'translation' as text and plays it again, the words seem pretty clear.


In 1985 two young men attempted suicide, and the family sued the British rock band Judas Priest, accusing them of hiding subliminal messages in the music that said "Do It!" when listened to backwards.

From memory, part of the trial was the defence taking a song, suggesting what words the court would hear in it played backwards, and then playing it backwards. e.g. this clip https://youtu.be/uyIsu93zAoM?t=1123 and showing that you hear the suggested words out of the noise.

The trial was thrown out, after deciding there were words and they were subliminal, but were not deliberate. The whole situation included: "In a pre-trial motion, the judge ruled that subliminal messages were incapable of being protected speech under the First Amendment to the United States Constitution, since they were by definition not noticeable and thus could not form part of a dialogue."

Documentary - https://www.imdb.com/title/tt0104140/

One more demonstration like this is in Matt Parker's "Clutching at Random Straws" lecture. https://www.youtube.com/watch?v=sf5OrthVRPA

did Grover drop an f-bomb? https://www.youtube.com/watch?v=1mU7t9GZ9Os

Andy Clark's Surfing Uncertainty[1] is a nice monograph of the topic

1: https://oxford.universitypressscholarship.com/view/10.1093/a...

I once fell off my bike and smashed my nose pretty badly.

To this day, when I trip and lose my balance for a second, I feel a shooting pain in my nose. It’s like it’s ready to start hurting again before anything touches it.

I heard nice phrasing for this.

We don't live in the real world, or even the world of our perceptions.

We live in completely virtual world of what our mind anticipates the perceptions will be in some number of milliseconds.

It makes complete sense when you realize that the speed of actually computing and thinking through every move would look more like a chess match rather than a dance (latter being instinctive moves).

Our body and mind are intertwined so tightly because we'd be dead.

I don't understand how this isn't obvious to anyone who's thought about it for a bit: Nobody's ever seen anything other than what their mind shows them.

Not just the human brain, but anything that is intelligent. Life itself is a prediction machine. Evolution selects for prediction power in an energy-constrained environment.

> Life itself is a prediction machine.

I beg to differ. That assumes evolution is teleological, that it isn't reactive. It's like saying positive and negative feedback loops are predictive. You're diluting the meaning of "predictive" to say something that sounds deep.

Particularly when talking about predictive processing in a neurological sense, you'll often see people blending prediction and feedback loops of any kind. It sounds sort of weird and pointless at first, but the point they're trying to make is that the same circuits could work to do both. So the brain moves the arm by "predicting" extremely hard that the arm will be in a different place, and waiting for the error to go away. From the top we know that it's really just a control system, but from any given neuron's perspective it could just as easily be a predictive one.

Considering these three statements:

- the brain predicts what its upcoming input will be,

- quantum biologists ask if the human eye is sensitive to quantum effects, and

- measuring quantum information under different bases result in a different quantum state of not only the measurer, but of the world being measured.

I wonder if it is possible that the brain uses its predictive power to change the basis under which the eye measures photons, resulting in different perceptions as well as a different reality. A bit of a crazy idea but I don't see any reason why it shouldn't be the case other than if it is shown that biological sensory organs are simply not that precise.


I can think of a few reasons to think that's not the case. For one, Rhodopsin isn't really under neurological control, so there's no way for top-down predictions to alter it. For another, what possible benefit would changing your evaluation basis give you? The whole point is that no matter what basis you pick everything works out the same!

This would break if the observation is done via recording > watch later

Has it ever been done that way?

Friston on the Free Energy Principle and Markov Blankets:


Speculative execution

Rich, rich analogy. SPECTRE and Meltdown attacks for the mind have to be a thing, possibly as interrogation and cross examination techniques?

We use SPECTRE and Meltdown attacks against brain every day, we call them "jokes".

Woah. That could make me a very dangerous person, because I am not funny at all.

Well... from the looks of it, we've gotten diddly squat from trying to think of the brain like the thing I'm writing this comment on, so probably not.

Political ads/campaigns do this all the time - especially the negative ones

Makes sense. If someone throws a ball into the air and you want to catch it, you predict where it will go. Along the way, if there is an error between prediction and actual position, you adjust for it.

Classic control theory :)

I think this is a very intuitive theory. I feel you can actually notice this consciously when you do some mundane repetitive task you've done a lot and something is off. For example if you lift a cup you thought was full and it isn't and for a moment it really throws you off. It's not just perceived as a difference but as something 'out of whack'.

Or when you lift an egg carton with one hand but it's only partially full and all the eggs are at one end and you lose your grip oops. I always rearrange our eggs to have left/right symmetry in the carton and my wife must think I'm nuts.

Or when you're walking and expecting a step to be there and it isn't.

Living with you would drive me insane, because I solved the same problem by always orienting the full half of the carton in back and adjusting my expectations to match.

I should have added that this is in a large household. So egg arrangement is self-defense.

This would certainly explain why my brain periodically suffers from meltdown.

One of my "executive function" problems is that I get overwhelmed when I think about things I need to do. I noticed that a sort of movie starts playing in my head of how to accomplish the task, i.e. the steps entailed, resources needed, etc.

What happens frequently is that my brain takes multiple discrete tasks and attempts to simulate each one's steps to completion simultaneously. I suddenly find myself at the front door paralyzed for five minutes, "Should I grab the trash since I'm going to go check the mail? I have to walk the dog, I can't carry all this trash while holding the dog. Where will I put the dog when I get the mail. Ok, put the leash on the dog, grab the trash... Crap, there's so much trash! Ok, just take the office trash out..."

ADHD medicine stopped working after a month. What has helped a lot is N-acetylcysteine. In fact, it's been several months and I'm comfortable saying that it has changed my life. The trainwreck thought loops give way to singular chains of focus.

Your comment on N-acetylcysteine is really left-field. Its not even listed as a use of that medication, whos primary purpose is to treat panadol overdose. Can you elaborate?

I hesitated to mention the specific supplement for that reason, but maybe it will help someone.

Apparently, the glutamate-glutamine system is implicated in psychiatric problems. Through my research I found that GABA deficiencies can cause ADHD symptoms. GABA is produced in the gut, I have stomach problems, so this seemed feasible. I learned that NAC increases glutathione and helps regulate glutamate. The effects people report point to an effect on this system.

The Wikipedia page for NAC has many references, but this is one review of its possible uses in psychiatric problems: https://www.sciencedirect.com/science/article/pii/S014976341...


Is it safe for the liver? A lot of nootropics substances that have positive effects can be pretty bad to the liver.

N-acetylcysteine is very effective (for some people) against anxiety, addictions, amphetamine tolerance, acne, and also some things that don't begin with "a".

Amazon also stopped selling it this year because people thought it was a COVID cure.

Yeah. I've had several convos with my health store owner about this. She told me she's found herself stocking up a lot lately because of the increased popularity and COVID misinformation-motivated stocking changes on Amazon.

Tell me more about acetylcisteine. How much per day? Is there a theory behind that use? Etc...

It has to do with the glutamine-glutamate system, glutathione, GABA and dopamine. There are various possible etiologies for ADHD, but I'm lucky this is one path I discovered that actually helped me. It also explains why Adderall and Wellbutrin didn't help me, as they affect dopamine and norepinephrine respectively.

I take at least 2g per day. Some NAC supplements have some selenium and molybdenum included, so in those cases it's important to be mindful of not taking too much of those trace minerals.

Check out the introduction of this paper: https://www.sciencedirect.com/science/article/pii/S014976341...

I'm sorry if that's a dumb question, but is monosodium glutamate consumption related to ADHD?

No, that's a smart question because MSG is so prevalent in our food. You'd have to ingest a lot of MSG to make an impact on glutamate levels, which would then affect GABA, which then affects ADHD symptoms.


How long did it take for you to observe a difference after you started taking NAC?

I noticed a difference on day one. I'll note that I also take l-glutamine to further the effect on the system I'm targeting. You'd also want a molybdenum and selenium source because NAC uses them up.

The effect is not dramatic like a stimulant. It's more like it makes my attention stickier, and allows me to hook into long problems more easily. It doesn't "feel" like anything, just causes a noticeable change in what I find engaging. One weird effect it has had is I completely stopped craving alcohol, news and social media. I usually spend hours on Reddit when I don't have anything on my plate. I'm talking 40k+ karma, multiple posts/comments per day type of addiction. I see multi-day, multi-week gaps between comments on my account now, which is unheard of for me. I know it's a silly heuristic, but it's an example of the behavior change.

I've seen much smarter people than me on Reddit say that effects may take 2-3 days. The supplement itself is pretty cheap, and negative side effects are minimal to non-existent. I am seriously astonished that such a common and accessible supplement has had the impact it has had on me. I personally think the cost/benefit ratio is so good that warranted skepticism can be overcome with a self-experiment.

If it doesn't have an effect, then at least a person can check off the "glutamate-glutamine system" checkbox in their quest to address executive function problems.


I thought excess glutamine was associated with neuroticism, anxiety, depression, etc., and that there was a positive correlation between glutamine levels and depression [1]? Do you think in your case maybe you have naturally very low levels of glutamine, making supplementation helpful?

[1] https://www.nature.com/articles/s41398-019-0500-z

How did you get to the dosage?

Do you notice that your visual center of focus shifts to different parts of the duck vs rabbit image?

While I strongly agree with the ideas of the article, the fact that you have to focus on different parts of the image to shift perception, altering the "bottom up" sensory data your brain receives, undermines at least a little the use of this example.

Brains that could 'predict' predators, and dangers in general, faster based on an 'educated' guess have obviously a higher survival rate. Or, to be precise, have a higher chance of making little copies of themselves afterwards.

Those naughty bunnies, there's nothing more sexy than the thrill to have survided...

Increased energy efficiency is probably just a side effect. Allthough of course, energy optimized brains, being big energy sinks aren' that small a factor.

But than again, brains back then didn't last that long before they were eaten by predators, so I still would think it is much more important not to be eaten than to be energy efficient.

'Premature optimization', 'Deliver fast' and all that. You know the drill.

So basically, the brain is a predictive Kalman filter.


I read once that “dopamine encodes prediction error” and it stuck with me. When your brain stumbles off the beaten path it wakes up in so many ways. Surprise is a powerful emotion.

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And in many cases only the prediction is used - people see what they want to see. It's a natural extrapolation of this (which can be very wrong and even deadly).

I'd argue that the main reason the brain predicts in the first place is how noisy our senses are. Your brain is doing everything in its power to tell you how the world actually is, but it isn't working with great equipment.

A kind of reverse-science if you will. Don't think about what you see, see about what you think.

And what we think derives from so many different sources.

It explains a lot.

Is this akin to asynchronous space warping or synchronous space warping used with VR headsets to improve perceived frame rates?

No, that has nothing to do with this at all. This is about making predictions and comparing them to new information.

Questions of efficiency are questions of survival. This framework resonates with my understanding of trauma responses.

Funny coincidence, I'm in the middle of reading of "a thousand brains" by Jeff Hawkins

“The observer is the observed.”

—Jiddu Krishnamurti

The brain has brainch prediction

the saying "My brain runs faster than my mouth" lends to this idea.

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