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The overfitted brain: Dreams evolved to assist generalization
- giantg2 5y agoI have too many dreams. It actually sucks since you don't get great sleep.
- reificator 5y agoI have a sleeping disorder and if I wake up and remember having a dream I almost always also feel well rested.
- giantg2 5y agoI remember 1-3 dreams every night. All my dreams are vivid dreams, where I know they are dreams while they are happening and I even have some degree of control over the content.
- throw1234651234 5y agoThose are "lucid dreams". My experience is that lucid dreams do lead to you be tired, probably because we tends to wake up after lucid dreams, though we wake up momentarily in normal life too, we just don't remember it. Maybe lucid dreaming overrides the benefits of sleep since the mind is actively engaged again. It's all fascinating, and there are no real answers whatsoever. Also, side questions: 1. Is your working memory pretty good? What about your IQ? 2. How vivid are these dreams and how logically-sequential are they? I.e. can you remember a clear chain of events from the dream?
- giantg2 5y agoThat's the term I was looking for. Memory is good. It used to be even better (I could recite important parts of meetings verbatim when I first joined my company 9 years ago). I think I'm still above average, but I'm not sure how to rule out bias on that. I've never taken an actual IQ test. When I was 5 my verbal/vocabulary skills tested on the level of a normal 10 year old. I was curious about IQ in college and took 2 unofficial tests which turned out very consistent with scores of 121 and 124. I don't really see a lot of value in IQ tests, even the official ones. The dreams vary. Some are very detailed. Some might not be, or it's just that I don't remember as much detail except in the final dream of the night (I sometimes remember up to 3 dreams per night). Usually they are logical/realistic, but sometimes include unrealistic elements (that I know during the dream are unreal). I can usually remember the chain of events in the final dream of the night very well. I can usually remember the order that I had the dreams in too. The earlier dreams I can usually remember the high level chain of events for the other dreams, but maybe not the smaller details. Any reason for the questions?
- throw1234651234 5y agoYea, I asked because ability to lucid dream (and remember those dreams) is closely tied to a high working memory. A good test for working memory is called "dual n-back". Basically, its a modified version of remembering a list of numbers / letters while the list is adding and dropping items, except with a spatial aspect. More info here if interested: https://www.gwern.net/DNB-FAQ https://www.gwern.net/DNB-FAQ Thanks for replying without context. Oh, and the reason for the chain of events question is personal curiosity. I can usually remember maybe 3 coherent actions, but there is rarely a clear start and end to the dream that I can remember.
- sweetsocks21 5y agoHave you had a sleep study? I used to have tons of vivid lucid dreams during sleep apnea. Now I have much less detailed dreams and they're less frequent, after fixing my sleep apnea. It's a bit sad because the dreams were fun, but I do feel way more rested these days.
- giantg2 5y agoNo sleep study. I do snore sometimes, but there are times, like on vacation, when I do sleep well. Maybe I'll look onto that. Thanks!
- htrp 5y ago> Notably, the techniques that researchers employ to rescue overfitted artificial neural networks generally involve sampling from an out-of-distribution or randomized dataset. The overfitted brain hypothesis is that the brains of organisms similarly face the challenge of fitting too well to their daily distribution of stimuli, causing overfitting and poor generalization. By hallucinating out-of-distribution sensory stimulation every night, the brain is able to rescue the generalizability of its perceptual and cognitive abilities and increase task performance. Bit of jump there from randomized/out of sample data to dreams are for generalization.
- toxik 5y agoAnd if the brain is overfitted, how can it generate out-of-distribution samples? Seems like wildly cyclical reasoning.
- boardwaalk 5y agoHow can computers calculate more accurately than the human brain but also have PRNGs or even true hardware RNGs?
- toxik 5y agoBut that’s the thing, it’s NOT random. It’s just unlikely scenarios. Dreams still follows the general model of the world.
- DavidSJ 5y agoThe brain is a lot of different components working together. Perhaps the bits which do statistical learning are functionally distinguishable from the bits which generate permutations on the data. (This is in fact how modern neural network training often works: start with a set of 50,000 images, run them through a bunch of permutations — translation, rotation, lighting changes, etc. — and produce a training set of 1 million images which yield better generalization when trained against.)
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- dr_dshiv 5y agoSeems like it isn't the randomization (high entropy) but rather the excessively low entropy. Sleeping brains are colder and more predictable (due to massive synchronization). REM sleep might be described as when our cortex turns on and tries sensemaking all the intrinsic oscillations.
- slfnflctd 5y agoAll I know is my dog sometimes yips in his sleep, and it can be fairly loud-- I will forever wonder what he's yipping at, or how that behavior could possibly be selected for. Brains are weird.
- zuzun 5y agoI noticed mine seems to have vivid dreams with barking after being woken up at night. Interestingly, the paper claims: > It is notable that approximately 50% to 70% of the time subjects report having a dream upon a sudden waking during sleep.
- ALittleLight 5y agoThat's interesting. I keep a dream journal and most of my entries are on days where I had interrupted sleep.
- thisismyswamp 5y agoWaking up and realizing you were dreaming is not the same as waking up and then dreaming
- Zircom 5y agoDogs and their ancestor's wolves are pack animals, maybe the sleep barking wakes the other pack mates making them more aware of their surroundings and better able to defend the pack from threats during the night? Maybe even The barking itself helps to ward off threats that would otherwise attack a sleeping animal. Is there even anything that preys enough on wolves where enough of them are being killed by it that the sleep barking would be selected against?
- tayo42 5y agoI thought dreams only happen durring rem and you are paralyzed durring rem stages. So you wouldn't be physically reacting to anything. I think those movements only happen in other stages of sleep
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- bpiche 5y agoAlso here https://news.ycombinator.com/item?id=23956715 https://news.ycombinator.com/item?id=23956715 https://news.ycombinator.com/item?id=27166536 https://news.ycombinator.com/item?id=27166536 https://news.ycombinator.com/item?id=23922449 https://news.ycombinator.com/item?id=23922449
- refactor_master 5y agoIt strikes me as rather unintuitive that the brain should be generating its own “out-of-distribution” data. It’s training itself on itself? Compare with an adversarial network, which can be composed of two entirely separate entities, whereas the biological brain is know to have a lot of “bleed-through”, e.g. our memories influence our perception and vice versa.
- prionassembly 5y agoCtrl-F "mania" says something. But on the level of barroom talk this sounds like a plausible explanation of the prodromal effects of sleep derivation.
- maxrev17 5y agoRead something recently theorizing dreams are to prevent the visual processing part of the brain from being repurposed when we sleep...
- throw1234651234 5y agoThat's a very interesting hypothesis actually.
- nucleogenesis 5y agoThis is what I want to read an article about
- elliekelly 5y agoCan you explain what that means? Being repurposed for what and why would that be something we’ve evolved to avoid?
- deleted 5y ago[deleted]
- jtsiskin 5y agoBitcoin mining
- aswegs8 5y agoDamn cryptojackers
- benp84 5y agoIt's like how the visual neurons of blind people get repurposed for other senses. Turns out this happens so quickly we can start to lose visual function in just the 8 hours our eyes are closed while we sleep. Can't remember source but heard this theory on a podcast.
- Lyapunov_Lover 5y agoYeah, I think that's David Eagleman's idea.
- o_p 5y agoOr sleep is needed to clean the toxins in the brain and dreams are just a funny consequence of disconnecting you from the world
- deleted 5y ago[deleted]
- pacman2 5y agoOh wow. Cell. Please also see previous dicussion: https://news.ycombinator.com/item?id=23956715 https://news.ycombinator.com/item?id=23956715 I vaguely remember an Indian Paper (or an author with an Indian name) that made the same claims and it got destroyed on HN. But my memory may fail me.
- klimt 5y agoIt's Cell Patterns, a new open access journal from Cell Press that started in April 2021.
- deleted 5y ago[deleted]
- t-writescode 5y agoI find it fascinating how a strong atheistic perspective and premise still tries to ascribe meaning to things. “Evolved to assist” and also most of the comments here that aren’t discussion of noticing animals dreaming.
- canjobear 5y agoThere's nothing contradictory about using teleological language to describe evolution. Evolution is an algorithm that maximizes fitness in a changing environment over time. It does things "in order to" maximize fitness in the same way that you or a robot might do things "in order to" maximize utility.
- t-writescode 5y agoEvolution is an algorithm that carries on traits that happened to be carried along when someone successfully mated. It speaks nothing of ‘fitness’ in any useful sense beyond ‘was successful at mating’. It _tends_ to yield things that correlate well with survivability to time of mating; but to imply anything of intent to it is inaccurate and ascribing purpose where there is none in this model.
- canjobear 5y ago> It speaks nothing of ‘fitness’ in any useful sense beyond ‘was successful at mating’. That's the definition of fitness. https://en.wikipedia.org/wiki/Price_equation https://en.wikipedia.org/wiki/Price_equation
- t-writescode 5y agoAnd yet this still speaks nothing to the 'purpose' implied by so many. Even the article says it's a statistical reality and nothing more.
- canjobear 5y ago
- babelfish 5y ago> Sleep loss, specifically dream loss, leads to an overfitted brain that can still memorize and learn but fails to generalize appropriately Curious where this claim came from. Obviously a lack of sleep will degrade your day-to-day performance, but I almost never have dreams.
- enneff 5y agoOr you just don’t remember them.
- babelfish 5y agoIt's a very distinct feeling waking up thinking "I did not dream last night" vs "I had a dream last night but don't remember it" IMO
- unparagoned 5y agoDo you have any evidence for that. It's very likely you had dreams with both experiences but just didn't realise it.
- dboreham 5y agoIt seems more likely that the brain has some kind of retention filter on dreams to try to sort the random useless signals from, for example when you deduce the structure of the benzene molecule. Probably all humans dream every night, unless there's some major issue with sleep, but only dreams passing the filter are remembered. Those on the threshold are "remembered as existing" but not the content.
- enneff 5y agoI think that probably has more to do with how recently you were in REM sleep (which is when most dreams occur). If you have the sensation of waking up from a dream, whether you remember it or not, you likely woke up from REM sleep. If you don't think you dreamt at all, then perhaps you just were in REM sleep much earlier during your sleep.
- quus 5y agoThey talked about this on an episode of Very Bad Wizards
- im3w1l 5y agoA theory of dreams should imo mention a few things: * Lucid dreaming. In particular does lucid dreaming prevent the generalization benefits? * Sensory deprivation hallucinations. It would seem this is connected to dreams, but is it? * Tetris effect. It seems that seeing a lot of a given pattern primes the brain the brain to look for it everywhere.
- FailMore 5y agoFor an alternative theory see https://psyarxiv.com/k6trz https://psyarxiv.com/k6trz
- pfdietz 5y agoI looked and was gratified it cited Francis Crick and Graeme Mitchinson's paper from 1983 that had a very similar idea.
- canjobear 5y agoThese theories are fun, but has it been shown that dreaming is an essential part of the function of sleep? If you could suppress dreaming but maintain sleep, would organisms still get the same benefit? Maybe what is required is simply a period of inactivity, and dreams are the effect of white noise cascading through the brain during that period.
- wiml 5y agoFrom what I remember, all of the phases of sleep are essential — if you suppress any of them, the person becomes unwell (possibly even dies). That includes the REM phase in which we sleep. I don't know if you can arrange to have healthy REM with zero dreaming, though.
- kayamon 5y agoI used to dream a lot; in the past year since I started taking THC as medication I haven't had any. I put this down to the THC basically letting you dream while you're awake, which seems to be more effective than doing it while asleep. As far as I can tell the purpose of dreams seems to be a way for the brain to visualize its own structure and repair itself (i.e. retraining your pattern matching on other inputs, not just visual).
- Severian 5y agoThis seems true to me. Correlation doesn't imply causation, but I've had my fair share of bizarre dreams where two completely separate concepts try to wedge themselves together in interlocking dream logic. No examples to speak of directly, as even holding them together after awakening is almost impossible.
- euske 5y agoMy pet theory is a bit similar to the article but in a more computer-architecture way. I tend to think that sleep is our brain performing "GC" our experiences, i.e. choosing what information to retain and what to discard. Since we don't have a separate circuit to do that, we basically reuse the same one (processor and its "bus") for a different purpose, by redirecting its output to /dev/null, and that's a dream. This kinda explains why we don't remember much of it because the result is meant to be discarded. There's no scientific evidence to this but it's quite fun to think this way. edit: the GC theory also explains why we have a better memory after sleep!
- xpuente 5y agoDNN is a nice hammer, but brain is not a nail. Hopefully this hype will disappear soon.