[HN Gopher] Spaced repetition can allow for infinite recall ___________________________________________________________________ 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? ___________________________________________________________________ (page generated 2022-08-08 23:00 UTC)