[HN Gopher] Spaced repetition can allow for infinite recall
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       Spaced repetition can allow for infinite recall
        
       Author : efavdb
       Score  : 130 points
       Date   : 2022-08-08 00:12 UTC (22 hours ago)
        
 (HTM) web link (www.efavdb.com)
 (TXT) w3m dump (www.efavdb.com)
        
       | cortesoft wrote:
       | This 'proof' seems a little suspect. It assumes that the rules
       | they have discovered hold for all situations. Even if they have
       | tested a large number of facts to remember, there is no reason to
       | believe their isn't some threshold where it doesn't hold anymore.
       | 
       | Also, they seem to be holding this learning technique like it is
       | a mathematical fact of the universe. I am not an expert, but
       | nothing in the human brain works that consistently. I can't
       | imagine every single person in the world can learn equally well
       | with this technique.
       | 
       | Although this is likely some form of satire, because there is no
       | way anyone could seriously think the brain works like this.
        
       | krychu wrote:
       | Shameless plug for a little tool I wrote to learn by repetition
       | on the command line: https://github.com/krychu/lrn
       | 
       | I use it whenever I have a few minutes of downtime, no fancy
       | state persistence between sessions.
        
       | dls2016 wrote:
       | I was anti-memorization until I went back to graduate school for
       | mathematics. I had forgotten (or never learned) a lot of things
       | needed to pass qualifying exams. At some point I ran across the
       | spaced repetition idea (maybe from the Wired SuperMemo article
       | [0]) and I gave it a try. I ended up using it to memorize large
       | portions of baby Rudin and Munkres' Topology, as well as some
       | algebra and a bunch of qualifying exam questions.
       | 
       | The qualifying exams were difficult until I reached some
       | "critical mass" of knowledge. Then I could regurgitate proofs and
       | even attack novel problems easily.
       | 
       | There's an analogy here somewhere to the "leetcode" style of
       | software engineer interview. On one hand qualifying exams and
       | leetcode questions are a stupid gatekeeping mechanism, but on the
       | other hand the best researchers/engineers I know have a huge
       | number of facts and examples memorized and ready at their
       | fingertips. I didn't think I needed to do so, but perhaps there
       | is something to suffering through the rote memorization phase to
       | make what comes next that much easier.
       | 
       | [0] https://www.wired.com/2008/04/ff-wozniak/
        
         | ren_engineer wrote:
         | I'd be really interested to see some research into integrating
         | spaced repetition into our actual education system. Almost
         | everything I see about it is adults learning, I wonder how much
         | we could speed up primary school education considering so much
         | of the "base" stuff needed to advance is rote memorization
         | anyway
         | 
         | seems like countries should be investing money in this,
         | potentially trillions in unlocked economic potential by
         | improving and speeding up education. I think I read something
         | like 20-30% of medical school students use SRS, yet only a
         | fraction of the general population uses it. Insane to me that
         | we have a tool like this and almost nothing is being done to
         | improve adoption.
        
           | pessimizer wrote:
           | Hundreds of millions of the world's kids were remote learning
           | for up to a year and a half. If there was any opportunity to
           | develop real tools to help with remote learning, it was then,
           | but we ended up with nothing, and remote learning still
           | sucks.
           | 
           | If anybody is going to integrate memory techniques into a
           | curriculum, it'll probably be some Silicon Valley charter.
        
         | kazinator wrote:
         | I remember the exact point in my life when I realized how much
         | difference rote memorization makes.
         | 
         | I had the opportunity to write some MC68000 assembly code, at a
         | time which was not too long after having written a complete
         | emulator for it in C. Writing the emulator required me becoming
         | familiar with every single instruction in all of its nuances,
         | and exactly what they all do.
         | 
         | So, having that behind me, I sat down to write this code and it
         | was like wow ... I could just spew the code without having to
         | look anything up. It was so easy!
        
           | therein wrote:
           | > I remember the exact point in my life when I realized how
           | much difference rote memorization makes.
           | 
           | I suspect this might have something to do with neurological
           | development. At least in my experience. Something about
           | memory and recollection "clicked" (not a skill but more a
           | capacity) at a really adult age for me.
           | 
           | Almost similar to being taught calculus after not knowing how
           | most physics formula are derived and then looking back in
           | confusion how you struggled with a straightforward thing.
        
         | snowpiercer wrote:
         | Don't you think you actually did well in your exams because you
         | really understood it and not because you blindly memorized it ?
        
           | nomel wrote:
           | I imagine it's possible that they are related. In my life,
           | I've only witnessed it as a required for being an expert at
           | any topic: experience and memorized knowledge, of a topic.
        
           | ozim wrote:
           | That is false dichotomy that is running around.
           | 
           | To really understand something first you blindly memorize -
           | but that is not enough, once you do examples and exercises
           | using what you blindly memorized you get to understand things
           | quicker, a lot quicker.
           | 
           | Not memorizing stuff and figuring things as you go is mostly
           | recipe for disappointment.
           | 
           | Like in chess - people think that chess players are somehow
           | super intelligent - but being super intelligent without rote
           | memorization of loads of chess settings will not help winning
           | grand master title.
        
             | Silverback_VII wrote:
             | >"To really understand something first you blindly
             | memorize"
             | 
             | Because of this sort of advice ppl equate memorization with
             | "not understanding" and cramming.
             | 
             | Never memorize things you don't understand.
        
               | orangepurple wrote:
               | They must be performed in lock step. Fully agree.
        
             | borroka wrote:
             | It similar to the question, "if you could do just one
             | exercise, what would you do?" And you have all these
             | answers, it is the squat, no, it is the deadlift, please
             | guys it is the power clean. It is not a useful question
             | because you will never be in the position of choosing just
             | one exercise to be done for the next month, year or decade.
             | 
             | Memorization is important and understanding is important,
             | and the two are not in any conflict whatsoever.
        
             | buscoquadnary wrote:
             | There's actually an interesting section of the book
             | "Moonwalking with Einstein" where it talks about a study
             | was done on chess masters where they showed them the board
             | in positions that would be impossible under the rules and
             | suddenly the master chess players didn't do all that much
             | better than random people.
             | 
             | The suggestion in the book was that really Grandmasters
             | have spent so much time practicing, that they have
             | memorized the game and the board to a certain extant that
             | allows them to more easily handle the board and all the
             | pieces on it cognitively.
        
           | Karrot_Kream wrote:
           | I've picked up a lot of (human) languages over my life, and
           | I've used SRS to great effect (I started on JMemorize, a now
           | defunct Java app.) I have a simple strategy:
           | 
           | 1. Read a text
           | 
           | 2. Lookup unknown word/grammatical pattern
           | 
           | 3. Create a flashcard for it
           | 
           | 4. Apply SRS
           | 
           | and it works great. I've also tried to use other people's
           | Anki decks and they've never worked particularly well.
           | Personally engaging with the material is still the
           | _prerequisite_ for memorizing it, but memorizing means you
           | don 't need to struggle to figure out basic concepts
           | constantly and can instead move onto the higher level of
           | meaning.
           | 
           | I've used SRS over the years for many, many things. I've used
           | it for memorizing divisibility rules, used it for annoying
           | math lemmas, used it for data structures, and more. Each of
           | the time I've attempted the material by myself and then
           | turned my knowledge/engagement into a flashcard. I've even
           | considered using it to learn tools like Blender so I can dial
           | in workflows.
        
           | pessimizer wrote:
           | I've really understood a lot of stuff that I've since
           | completely forgotten. For example, if you don't speak your
           | native language for 20 years, you'll be surprised how hard it
           | is to find any of it when you need it.
        
         | k__ wrote:
         | Oh, could you go into more detail about math and memoizantion?
         | 
         | What did you do?
         | 
         | I had the impression, these techniques only work well for
         | languages, but I really would love to get better at math.
        
           | mkl wrote:
           | Have a look at this article by Michael Nielsen:
           | https://cognitivemedium.com/srs-mathematics
           | 
           | Old HN discussion:
           | https://news.ycombinator.com/item?id=18895613
           | 
           | Or this one: https://cronokirby.com/posts/2021/02/spaced-
           | repetition-for-m...
           | 
           | Hasn't been on HN before so I just posted it:
           | https://news.ycombinator.com/item?id=32390730
        
         | xkfm wrote:
         | That Supermemo article in Wired hooked me. I still remember
         | where I was when I read it and the feeling of reading it. I
         | still use Supermemo daily, and it's one of the programs keeping
         | on Windows. Anki (and every other SRS program I've tried) just
         | doesn't compare as soon as you move beyond a list of
         | flashcards.
         | 
         | That said, having used Supermemo for over a decade at this
         | point, the hardest thing about SRS is deciding what's actually
         | worth reviewing for a long period of time. I delete (really
         | remove from repetitions) cards from my collection almost on a
         | daily basis.
         | 
         | There's a lot of stuff that seems really important that I just
         | didn't care about after even three months.
         | 
         | Supermemo's incremental reading basically lets you schedule
         | chunks of text or images (alleged video too) like a flashcard
         | from Anki. So, instead of bookmarking articles and never
         | reading them, I can put them into Supermemo and know I'll
         | eventually review it.
         | 
         | It basically counts as a separate type of flashcard, but all
         | your reviews are mixed by default. So on a typical day, I'll
         | have maybe 20 flashcards to review, and then another 10-20
         | articles.
         | 
         | Supermemo saves where you last were reading, so when I get
         | bored of an article, I just hit next and go to the next one.
         | Eventually, you'll process an article down to individual
         | flashcards like you'd put in Anki, or remove it from your
         | review process altogether. Also, you can just leave the entire
         | article in there if you like rereading it.
        
           | TeeMassive wrote:
           | Is Supermemo only available as a SaaS?
        
             | orangepurple wrote:
             | No it's primarily an awful Delphi for Windows desktop
             | application that is extremely fragile.
             | 
             | But once you know how to "hold it correctly" it will be
             | your companion for life.
             | 
             | I run it in a virtual machine with all its legacy
             | dependencies like IE. Forget about running it on Wine, it
             | barely works on any version of Windows (lol)
        
               | TremendousJudge wrote:
               | If actually using it has this huge friction, how do you
               | manage to use it every day? I always have a hard time
               | creating habits out things that are hard to "start" doing
               | every time.
        
               | orangepurple wrote:
               | I don't. I developed my own spaced repetition software
               | from first principles based on the latest research :D
        
               | samatman wrote:
               | I would love a link dump if you have that handy and don't
               | mind. I'm working on something with a spaced repetition
               | component.
        
               | klipt wrote:
               | Is your code open source? Seems like Anki could do with
               | some competition.
        
               | wizofaus wrote:
               | What's https://www.supermemo.com/ then? I just signed up
               | to give it a go (requires CC #, but free for a month).
               | Still haven't found good spaced repetition vocab learning
               | site that works well for me.
        
               | jan_Inkepa wrote:
               | https://super-memo.com/ is the software that's being
               | talked about.
        
               | wizofaus wrote:
               | Ah OK, though I'm still curious how there can also be an
               | apparently unrelated online offering at supermemo.com.
               | FWIW, from the very brief experience I've had so far I'm
               | not super impressed, but I'll try sticking with it for at
               | least the month of the free trial.
        
           | Karrot_Kream wrote:
           | Yeah I agree. Anki has a failure mode for me that I
           | eventually accumulate > 5000 flash cards and a review session
           | can take an hour or more. Knowing what to review is really
           | difficult. I'll give Supermemo a shot, I've always heard of
           | it as the gold standard but never tried it.
        
         | Silverback_VII wrote:
         | Memorization is powerful only if you memorize the right stuff
         | like Machiavelli's Prince instead of a phone book.
         | 
         | Incremental reading (supermemo 18) to dissect books is even
         | better I think.
        
       | cptcobalt wrote:
       | I see this argument as semi-fallacious, since it's really asking
       | "can you recall infinite things on an infinite timescale using
       | this method"? Sure, the math might add up, but humans are
       | reliably fallible. I do agree, from practice, that practicing
       | spaced repetition can increase the breadth of knowledge beyond
       | that of "casual learning", but I've seen my brain fail on aged
       | entries too.
       | 
       | Nicky Case's intro to spaced repetition is pretty stellar, both
       | as a crash course and the reasoning behind it:
       | https://ncase.me/remember/
        
         | jacb wrote:
         | More than semi-fallacious - the math doesn't add up, because
         | you run into the Bekenstein bound, which limits how much
         | information you can pack into a volume.
        
           | jerf wrote:
           | This is why I don't use spaced repetition. The danger of
           | becoming a black hole is just too high. Forgetting things is
           | well known to be highly evolutionary advantageous, because
           | all the critters that remember everything and turned into
           | black holes stopped reproducing. Very dangerous stuff to play
           | with.
        
             | jacb wrote:
             | Ha! Certainly none of us will get anywhere close to this
             | bound, no matter how much time we log in Anki. But the OP
             | asked "Would an infinitely-long-lived, but forgetful person
             | be able to recall an infinite number of facts using this
             | method?", and the answer is a surprising "no, you turn into
             | a black hole".
        
               | ben_w wrote:
               | Sometimes even just _one_ piece of knowledge can turn you
               | into a black hole. It's why nobody remembers every digit
               | of Graham's (phone) number.
               | 
               | ;)
        
               | jrussino wrote:
               | I know we're all playing around here, but surely the
               | answer must be that there's a limit rooted in the
               | specific biological/chemical implementation of memory in
               | the brain that our hypothetical "infinitely-long-lived,
               | but forgetful person" would hit before the Bekenstein
               | bound (probably long before) and therefore it's
               | impossible to turn a brain into a black hole via that
               | mechanism.
        
             | orangepurple wrote:
             | The more you learn the more you gain the ability to encode
             | new facts with fewer "bits." Thanks to associative memory.
             | Adults have an advantage in learning in this regard.
        
             | makeset wrote:
             | Tragic really how smart people know perfectly well that you
             | shouldn't exercise if you don't want to accidentally turn
             | into a grotesque muscle freak, but rarely use the same
             | caution in brain exercise.
        
         | shkkmo wrote:
         | The argument is wholely fallacious and the author knows it and
         | is just being silly. The entire argument is based on
         | assumptions that only hold for smallish numbers of items. It we
         | get to larger finite numbers, such as the number of possible
         | states of a human brain, those assumptions are clearly false.
        
       | Silverback_VII wrote:
       | there are only a limited amount of things you can memorize
       | because your lifetime is also limited. Piotr Wozniak the creator
       | of supermemo, the first spaced repetition program, talks about it
       | on his site:
       | https://supermemo.guru/wiki/How_much_knowledge_can_human_bra...
       | 
       | this guy is a genius in my opinion.
        
         | orangepurple wrote:
         | I am in no way affiliated with the guy but you should read the
         | seminal papers published by John R. Anderson.
         | 
         | This guy has been in this game since the 70s
         | 
         | Carnegie Mellon University Professor of Psychology and Computer
         | Science
         | 
         | http://act-r.psy.cmu.edu/peoplepages/ja/
        
       | tpoacher wrote:
       | I'm a fan of spaced repetition too and have incorporated Anki in
       | my life in more ways than simple memorization.
       | 
       | But calling it "infinite recall" is a bit misleading. Improved
       | long-term retention at the cost of minimal unintrusive prompting
       | is probably closer.
        
         | comfypotato wrote:
         | The article is a joke proving how an immortal person could get
         | infinite recall with spaced repetition.
        
       | cehrlich wrote:
       | I've been using Anki for language learning and it's a superpower.
       | After just over two years I passed an exam that requires a
       | passive vocabulary of about 10,000 words. Other people who
       | grinded harder than me have managed it even faster, some in under
       | a year.
       | 
       | However one big mistake people make is to think an SRS helps you
       | learn. That's not true. It helps you not forget things you've
       | already learned. You still need some real world interaction with
       | the material.
        
         | borroka wrote:
         | >> It helps you not forget things you've already learned.
         | 
         | The argument is quite weak when we discuss learning words in a
         | foreign language. You learn that lunch is "almuerzo" in
         | Spanish, but is it learning or just memorization/association?
         | To me the lines are blurred, even at first sight of the word.
         | 
         | I used Anki myself to learn foreign languages and it is
         | tremendously effective for words and short sentences too. I use
         | it also for words in my mother tongue, and it made be much more
         | articulate than I used to be.
        
           | _dain_ wrote:
           | >You learn that lunch is "almuerzo" in Spanish, but is it
           | learning or just memorization/association? To me the lines
           | are blurred, even at first sight of the word.
           | 
           | I think there's a difference. "Almuerzo" -> "al muerzo", I
           | know "al" means "the", from Arabic, I look up the etymology,
           | the "muerzo" is from Latin "morsus", from which we get
           | "morsel" in English. Mnemonic: "the morsel". Then I can guess
           | that the form of the verb is almorzar, which is indeed the
           | case. Even learning a simple word embeds and thickens a web
           | of associations in one's mind. SRS strengthens this, makes it
           | scale better.
        
       | dhosek wrote:
       | It kind of reminds me of what I used to say about 9-ball pool:
       | You can play with an infinite number of players but not everyone
       | will get a turn.
        
       | buscoquadnary wrote:
       | I'll just throw out I am a big fan of spaced repetition I highly
       | recommend it to everyone. For those complaining about "infinite
       | recall" you aren't wrong, the pioneer of this movement Piotr
       | Wozniak, even has an article on his wiki
       | (https://supermemo.guru/wiki/Piotr_Wozniak) about how the upper
       | bound of languages you can learn fluently in a lifetime is
       | probably somewhere near 5. But the point isn't to remember
       | everything forever, the purpose is to help you learn better.
       | 
       | My flow right now for learning things is.
       | 
       | 1. Find sources copy and paste large swathes of revelevant text
       | and images.
       | 
       | 2. Re-read the copy and pasted text and create a detailed summary
       | of it in my own words.
       | 
       | 3. Come back a few hours or day later and summarize the summary.
       | 
       | 4. Use this as the basis for cards to load into Anki.
       | 
       | It isn't about building a massive repository of facts, and you
       | can do plenty with just steps 1-3 without ever using Spaced
       | Repetition, but the reason I fell in love with spaced repetition
       | and have jumped on it so heavily is that I've done steps 1-3 with
       | a lot of information and subjects, and over time have forgotten
       | all but the most basic things about them. This makes me feel as
       | if part of my time or life was wasted, because if I have to
       | revist something again latter like Sorting Algorithms it feels
       | like starting over. Whereas things I have started to use spaced
       | repetition with, I retain the fundamentals the "outline" of the
       | subject for much longer, and if I have to revisit it I feel much
       | more familiar because to paraphrase Piotr Wozniak. The things we
       | remember well are things that are well located/connected within
       | our knowledge tree.
       | 
       | For those IT people out there as well the other thing spaced
       | repetition and especially Anki is super useful for is learning
       | how to use your tools more effectively because it helps you to
       | remember those features and tricks that you don't use often but
       | super speed things up. For example I used grep for a long time, I
       | often found myself having to hit up the man page, or the DDG if I
       | needed to do something unusual, or more often I'd end up trying
       | to cobble something together with the tools I had. I reviewed a
       | "most useful flags" in grep page a few months back and decided to
       | Ankify it. I am now an order of magnitude more proficient with
       | grep because I can quickly recall the flag or option I need to
       | provide to do something wonky with it when I need to, simply
       | because I remember a relatively obscure feature, that I don't use
       | often and would've forgotten otherwise.
       | 
       | Finally in conclusion
       | 
       | The 4 states that made up the Austro-Hungarian Empire were
       | Boznia-Herzgovania, Croatia-Slavonia, The Kingdom of Hungry and
       | Cieslenthia. Because sometimes memorizing one or two random facts
       | just makes life more interesting.
        
       | tiborsaas wrote:
       | Finally, a mathematical proof to take as many pictures as
       | possible is a good idea :)
        
       | dinobones wrote:
       | TLDR I know how to use latex and took calc 2, I want to look
       | smart on the internet.
        
       | barking_biscuit wrote:
       | I mean sure. The trouble is in order to keep the review time per
       | day fixed you need to vary the rate at which you introduce new
       | facts, and as time goes on the interval between when you can
       | afford to introduce new facts will grow to be infinite.
       | 
       | The model also doesn't account for how you feel about doing this
       | activity. This includes the pain of not doing reviews for several
       | days and then having to catch up. The probability you eventually
       | throw in the towel is also a function of how useful you're
       | finding the activity, which in this case since we've opted to
       | keep the per-day study time as fixed will likely be when the
       | interval that you are required to wait before you can add a new
       | fact becomes so large you are routinely bothered by occurrences
       | where you encounter a fact you wanted to put into your SRS but
       | didn't have the bandwidth to.
       | 
       | Source: input 35 new vocab a day into Anki while learning
       | Japanese a decade ago and grew my vocab deck to 18000+ cards.
       | Reviews would take several hours a day, and at one point I
       | stopped adding new words to try and wait for the daily review
       | load to go down. When it never did despite this, I just deleted
       | the entire thing and say fuck it.
        
         | allenu wrote:
         | That growing backlog is a big issue with this type of
         | scheduling. I think it's one of those almost "unexpected" side-
         | effects of spaced repetition. I mean, if you did the math up
         | front, you should know generally how busy you're going to be
         | over the next few weeks based on how many cards you're
         | reviewing per day, how many new ones are coming, and how you're
         | scoring with each card, but it's not really something people
         | do, nor does the UI show you that.
         | 
         | I wrote my own spaced repetition app (see my profile) and one
         | thing I experimented with is an "ETA" function which goes
         | through your deck and tells you how long before you learn
         | everything "well enough", where "well enough" just means the
         | intervals between all cards is at least some fixed threshold,
         | like one month. I was surprised that even with a few hundred
         | cards and a fixed number of cards reviewed per day, it would
         | still take a few months.
         | 
         | I haven't added the ETA feature yet, but if I do, I think I
         | would need to make sure to show the user how adding new cards
         | affects that target date, and also how reviewing more cards a
         | day or fewer cards a day affects it. I think there's a way to
         | design a nice UI so users feel like they are in control of that
         | end date so they can choose if it's worth it to add new cards
         | or not.
         | 
         | I think a spaced repetition app should also make "falling
         | behind" not feel catastrophic. I think memorizing a smaller set
         | of facts consistently is better than trying to memorize a
         | larger set and then giving up, and an app's UI can probably
         | help to that end.
        
         | ceeplusplus wrote:
         | Not quite. The review intervals increase exponentially, so if
         | you stop adding new cards the workload quickly goes to single
         | digits per day in a few months.
         | 
         | 35 a day is excessive for sure. Even with foreign language
         | stuff which is the lowest time to solve per card, I limit
         | myself to 10 new cards/day. Math problems 2 new/day. Daily
         | workload ends up around 50-100 cards, which is very manageable.
         | You do need to be consistent though.
        
         | martindbp wrote:
         | Yeah, I've got 9000 reviews waiting for me in my old Chinese
         | Anki deck, at some point you always fall off the wagon. I've
         | changed my mind several times on SRS going back and forth, and
         | my conclusion is that, for language, I think it's better to
         | split your time with 90% on consuming meaningful input and 10%
         | SRS, because learning in context with real content that you're
         | interested in allows you to encode your memories much more
         | efficiently. The problem with pairing available SRS systems
         | with consuming real content is that they don't take into
         | account "natural" repetitions, e.g. when you encountered a word
         | in a movie outside the SRS, so they tend to underestimate how
         | well you know a word. But also since "natural" repetitions are
         | baked into the SRS model via parameters that fit the "average",
         | it also tends to overestimate your knowledge of a lot of other
         | items. Combined, you just have a very inefficient schedule that
         | takes too much of your time for too little gain
        
           | orangepurple wrote:
           | A prioritized queue of stuff to learn may be a better
           | solution than staring at "over 9000" things to review. Such a
           | queue would mean you simply bite off as much as you can chew
           | every day and don't perpetually fall behind, assuming the
           | priority queue has a small degree of randomness and is
           | recomputed daily based on the decay rate of all modeled
           | facts. Do you agree?
        
       | mikkergp wrote:
       | I know this is just a joke, but there was an interesting Radiolab
       | on memory and forgetting. It posited that forgetting is an active
       | process, and analysis a person who was disabled in such a way
       | that their forgetting process didn't work led to some very
       | undesirable outcomes:
       | 
       | https://radiolab.org/episodes/91569-memory-and-forgetting
        
       | rideontime wrote:
       | Sincere question: is this satire?
        
         | NotTameAntelope wrote:
         | Honestly yeah I think it's a form of satire[0], which IMO takes
         | nothing away from the joke.
         | 
         | Satire is fun! And I think the folks taking the math seriously
         | are probably in on the joke.
         | 
         | [0] or whatever brand of comedy "imagine a cow approximates to
         | an oblong sphere" is. "This is strictly satire" is not a hill I
         | must die on.
        
       | kelseyfrog wrote:
       | This is false if memory's are stored physically in the brain.
       | Unless there is an increase in brain volume, this process will
       | eventually hit the Bekenstein bound. I don't care if the upper
       | bound is "effectively infinite," that's not what the proof
       | claimed.
        
         | Invictus0 wrote:
         | Undoubtedly the worst comment on all of hacker news
        
           | kelseyfrog wrote:
           | Truly honored.
        
         | orangepurple wrote:
         | Neural connections are pruned regularly
        
         | marcodiego wrote:
         | > "effectively infinite,"
         | 
         | This is what I have been thinking. If whatever you can remember
         | is bigger than all experiences and lessons you could remember,
         | then your memory is effectively infinite. I don't know if
         | having a continuous effectively infinite memory is good or bad.
         | As someone who play the classical guitar, having a better
         | memory would do wonders for me.
        
           | [deleted]
        
         | monktastic1 wrote:
         | Proofs rely on assumptions. In this case, they state outright:
         | 
         | > We first posit that the number of days T that a fact can be
         | retained before it needs to be reviewed grows as a power-law in
         | s, the number of times it's been reviewed so far, ...
         | 
         | Obviously this _assumption_ will be false in our physical
         | universe, but that doesn 't make the proof itself invalid
         | (edited).
        
           | kazinator wrote:
           | In logic, the soundness of a proof in fact has to do with its
           | interpretation in some universe of discourse. To be sound,
           | the argument has to be deductively valid, and its premises
           | have to have true interpretations in the chosen world where
           | it is applied.
           | 
           | Here we have a valid mathematical argument which is unsound
           | in this world, where its assumptions do not hold up.
        
             | monktastic1 wrote:
             | You're right. I should have said invalid rather than
             | unsound. I still don't see the point of the criticism,
             | however. Lots of interesting things can be learned by
             | starting from approximations to actual reality.
        
         | vntok wrote:
         | > I don't care if the upper bound is "effectively infinite,"
         | that's not what the proof claimed.
         | 
         | Very interesting. Do you typically process all claims as
         | literally as you just did for this one, notably when you're
         | interacting with people outside of the Internet? In which case,
         | do most people react positively to your behaviour, or do they
         | get annoyed because "you know what I meant"?
        
           | kelseyfrog wrote:
           | Internet "well actually," culture made me this way. I preempt
           | rebuttals I'm not interested in.
        
             | _dain_ wrote:
             | I don't think you're actually a real frog.
        
       | kazinator wrote:
       | It's cute math, but doesn't take into account the inexplicable
       | differences between the retention of seemingly similar facts.
       | Some items stick very well, whereas others suffer from lapses.
       | 
       | In my Ankid ecks, I have items that have 10+ year intervals. And
       | some, which were introduced at around the same time as those,
       | which have intervals in months, beaten down by lapses.
       | 
       | Anyone who thinks that some simple math leads to infinite recall
       | has not suddenly lapsed on a card whose interval had reached 7
       | years.
        
         | orangepurple wrote:
         | I don't recommend allowing Anki items to have an interval of
         | over one year because the crude SM-2 algorithm does not capture
         | the per-item effect of exponential decay in memory. Multiplying
         | interval lengths by per-item ease factors is suboptimal and not
         | the same. Unlike, for instance, ACT-R, which unfortunately has
         | no good publicly available user interface. A good
         | implementation of a neural memory fact model will track
         | strengths of associative memories in addition to the per-item
         | exponential forgetting curve. Keep the Anki intervals capped at
         | one year until something better comes along.
        
           | kazinator wrote:
           | Problem is it seems you're then throwing under the bus all
           | those items you recall perfectly well that have 6+ year
           | intervals, which don't require yearly review. Arguably, you
           | could just retire those; but then sometimes they lapse, as I
           | noted: how do you decide what to retire?
        
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