Brains Speed Up Perception by Guessing What’s Next
quantamagazine.org
quantamagazine.org
There are so many strands of neuroscience that show predictive coding now. There's a really nice example in the use of common vs unusual words in sentences. If you're using fMRI to scan someone while they read these two sentences:
The jam on the motorway made everything slow.
The jam on the motorway made everything sticky.
You'll see a flash of activity when people read the word "sticky" rather than the more common word in that context "slow". The theory is that when everything in the sentence proceeds as predicted there's very little need to update prior expectations, but when you come across something that goes against previous predictions it's a signal that something needs to be actively thought about.
If you explore the meaning of language enough you'll realize it doesn't really make sense.
Everything is based on context and assumptions that we take for granted when communicating. But if you dig deep enough (and it's really not that deep anyway), you'll notice that pretty much anything you say or write can be interpreted in multiple different ways, which means there's no one absolute meaning to any expression of language.
Meaning comes from interpretation, which is subjective and unique to the person doing it.
Interesting exercise: for a day or a week, make an effort to think how anything that someone else says to you is actually true - asume they are always right and think about how to justify it. It's really amazing, at first it's really hard, but then you discover you can always just interpret what they say in a way that fits your views.
1: They went for a walk as a single activity on top of their regular daily walking, and that walk was a mile long.
2. They walked a total of 1 mile throughout the entire day, including regular walking around the house/office etc.
I do agree with the sentiment though, there definitely are plenty of unambiguous sentences you can say in everyday conversation.
Perhaps "my refrigerator is currently powered on" is an arbitrary example that works.
In that example, the first context is English language, then knowing who I is, then what a mile is, and a treadmill and today. All of those are contextual. Even mile. How long is a mile? Like any physical measure, it actually varies, because it is defined relative to something else which varies. The meaning of English language has also varied over time, that sentence might not make any sense to someone reading it in 20 years. And then when is today? May 7, 2019 - which is also a relative measure of time and not even that precise.
And then finally, what if you were lying? Did you really walk a mile today? How can I be sure? And how can you be sure I understand the same meaning from the words you say or write?
> the first context is English language
Let's ignore this context. If you don't understand English then you shouldn't be expected to understand an English statement regardless of context.
> How long is a mile?
That depends on what time and space you are in. But that's ok. All such measurements are relative and defined by non-natural constructs. But we can be realistic and assume a mile is whatever our government has decided.
When I tell you "I ran a mile", I'm not telling someone in Australia I ran a mile. I"m telling you that. If we are speaking over the internet it might complicate things, but we only have to resolve the meaning of mile once for our relationship, and all proceeding discussions will use this meaning.
I would argue that this makes the word mile unambiguous in the sense that you are saying. If we had to assert each time what I meant by a mile, then that would be ambiguous.
> that sentence might not make any sense to someone reading it in 20 years
Evolution of language is a separate phenomenon. We don't need to consider that. Only what the language means today right now as I use it. That's the utility of language. For older English texts, we have literature which matches our common vernacular to the vernacular of the time. Foreign translations are out of scope for the same reason listed above. Since we have mappings between today's English and yesterday's English, I would again argue that this is not a source of ambiguity.
> And then when is today? May 7, 2019
That doesn't have anything to do with language. That is a chronospacial coordinate. It represents a certain degree of completion of our orbit around the sun. It isn't a measurement of time at all. It's only relative in the sense that all time and space measurements are relative to the spacetime coordinate of the Big Bang.
Time is inherently a relative concept. We don't have time unless we are comparing (relating) two different frames. We define one in terms relative to the other (motion, state, etc). In a single, non-relative frame of reference time just doesn't exist.
> And then finally, what if you were lying?
Again, this has nothing to do with language. You aren't trying to guess what I'm thinking, you're trying to understand what I'm saying. That's what language parsing is about. Discussion of motivations, misdirection, etc. is irrelevant.
Well, that's the problem. It might seem obvious to you now, but it is not obvious to everyone all the time, which is what makes any statement ambiguous.
Additionally, I don't know the purpose of what you are saying. For example, you might say you ran a mile because you wanted to express you were tired, or because you wanted to imply you are healthy, or who knows why, it is definitely not clear from the statement alone what you wanted to convey, which is the main problem.
We feel something internally and then we try to express that in words, hoping that those words will mean the same to the person perceiving them. That process is highly suceptible to noise in many forms, like the other person not hearing you correctly, being distracted, being stressed out, or maybe they speak a slightly different version of your language and some of the words or expressions mean something a bit different to them than to you.
In the end, any statement doesn't have meaning by itself, it only acquires meaning when someone interprets it and understands it in a certain way. That is always a subjective process.
Language is certainly subjective, but I would argue that we can make certain concessions on what context truly is "obvious" and what isn't. And I think the matter of what level of precision is acceptable enough to consider a statement or idea "understood" is up for debate and is also contextual.
At some point, any extra information is just that, extra information. The core idea may have been expressed fully, even if there are certain small ambiguities or if the listener wishes to draw insight from the statement beyond the basic sentiment expressed.
Language is an incredibly useful tool and it works very well for most of our daily lives and many important things without thinking too much about it.
It's just very interesting to me to see how something that seems so solid, in some ways is much more fluid and fuzzy.
Thank you for keeping this thread going, really enjoyed discussing this.
Throwing exceptions is expensive
I think the ELI5 way to look at it is pattern recognition and then using those patterns for not only prediction, much like ML models, but also in other things like physical actions, emotional response, etc.
Many theorize it is that these heuristics are trained and the “path more taken” is the default. It’s when a stimulus doesn’t fit that path that the brain has to decide whether:
1. Is something wrong with this?
2. Is this a new path I need to start paving to speed up future processing?
Whether or not that second choice is made is dependent on lots of things co-processing at the time: Emotion, attention, attitude, etc. How much that path is paved is also dependent on those things.
This idea is fundamental to areas of study like symbolic systems at Stanford [1]
I noticed that my gaze actually jumped back to "jam" when I read "sticky".
https://fabiensanglard.net/quakeSource/johnc-log.aug.htm
I wonder if you could design a game around this by drawing BOTH the predicted motion and a ghost image of the last known verified server position of players, and then deliberately introduce 500ms of latency. The gameplay would then be about tricking your opponents into thinking you were going somewhere you're not.
The engine also reuses code from other games in the Quake series, including QuakeWorld, and Quake II, but this reuse is minimal in comparison to that of the original Quake.
This would be fun. Maybe call it "Kalman's Revenge" or something.
Also interesting, on an unrelated note:
> Romero is now gone from id. > There will be no more grandiose statements about our future projects.
Even brains aren’t safe from speculative execution vulnerabilities
I normally hate soda water, but that time I especially hated it.
Note you could do the same for a vodka drinker; it gets more interesting if they're already in the bag...
Falling of the stool, uproariously laughing drunk. Someone else who was in on it (I wasn't, I was getting drunk for real on beer) produced an old Nintendo Game 'n watch where the water drunk guy got the top score of any of us. Apparently being drunk like this didn't affect his reaction time at all. No hangover, Immediately sobered up post-reveal and claims he felt totally drunk. (Then almost immediately drank a family sized rum or something - kids those days, sheesh).
It'd be great if you could get that enjoyable drunkeness feeling like so as easily as by pouring booze down your neck...
"Ladies and gentleman, pivot your startups, go!"
"We're the world leaders in getting neural nets drunk, then making them classify with a hangover..."
Yeah I'm sorry, hasn't been a great week...
Someone made this latter substitution for me after a particularly intensive round of basketball...
Dibs not being tasked with building the culling into earth's engine!
Cue: a thing said or done that serves as a signal
Queue: a line or sequence of people waiting
[0] http://www.u.arizona.edu/~kforster/priming/ [1] https://link.springer.com/article/10.3758%2FBF03196307
My model, which was basically guessed from common-sense principles (what would a flip-flop's output look like if there were no clock and the "update" signal were not discrete?), used equations that were similar to what would eventually become the GRU update equations. And the fit with the data was gorgeous: it took one parameter (a time constant that scaled how quickly sensory information was integrated with the current prediction) and the R^2 was north of 90%.
Probably since a few minutes after the first time a neuroscientist saw a magician's act.
Just yesterday playing guitar.. I was fighting playing the wrong note cause my brain was guessing that was the next note because so often in so much music it would be. It was something like 3 notes that are in a particular scale and my brain really wanted to play the next note in the scale instead of the correct next note.
In all activities our brain internalizes how to do things and we can suddenly do them without having to think consciously about how it's happening.. huge in sports and anything with motor skills... music, video games, etc, etc..
It’s a great combination of some of the sensations you get from playing music, and executing things well in a video game.
osu! - and most rhythm games, I would think - is the exact same way.
Highly relevant to all this is Hal Galper's approach to jazz education. Example: https://www.youtube.com/watch?v=y_7DgCrziI8
Whatever "muscle memory" is, it's in your brain.
It's when you've done something so many times your brain has pathways for it so you can do it unconsciously.
It's like riding a bike. There are like 10 things going on at the same time and you don't even think about them once you know how to ride a bike.. your brain is doing a lot of the work in the background.
Heck even using your balance to walk around is the same thing.
- I have some accent when speaking english but not much. - Some colleagues from my home town have much stronger accents.
When they speak some words in weird ways I find that american colleagues just understand and move on.
When I speak a word in a weird way they'll either laugh, bc it is funny, or just be confused.
I think its because they are paying more attention to my colleagues with stronger accents because they know they have to.
But with me they'll be more relaxed and get caught off guard when I pronounce words wrong.
We learn how to create representations of the present by conditioning them on correct prediction of the future. We build world models and thus get to imagine future scenarios, very useful in planning our actions both for achieving higher rewards and avoiding dangers.
So we get sensory representation and world modelling for free - no need to be taught explicitly, the teaching signal is just the link between present and future.
https://slatestarcodex.com/2017/09/05/book-review-surfing-un...