How Much Brain Capacity Does Each Person Have?

[Winzer]

Is is possible to quantify how much "space" a human brain has? Kind of like in terms of hard-drive space?
I am sure this depends on the person.

 

[somasimple]

A lot, a lot more than an hard drive.
http://www.merkle.com/brainLimits.html
http://faculty.washington.edu/chudler/facts.html

 

[Andy Resnick]

0.7 liter.

 

[Cincinnatus]

There's no such thing as general purpose memory in the brain. So the answer would depend on the type of memory (episodic, semantic, procedural, etc) and on its salience.

So the "memory capacity" would be highly dependent on the type of memory.

As far as I know, the one area in which this kind of question has been extensively studied is with working memory. Though you may want to liken this more to RAM than to hard drive memory. People usually claim that the "magic number" is 7 plus or minus 3 items that can be simultaneously held in working memory... Though this is a somewhat misleading figure in the context of many tasks... Strategies like chunking and rehearsal can improve these values.

 

[confused2008]

Some people with photographic memory must have huge brain capacity because of the resolution of the images they have so as a stab in the dark it could be as much as hundreds of thousands of terrabytes.

 

[cam875]

you can't measure a human brain's capacity using bytes. It doesn't work like that. Neuroscientists have been studying how the memory is stored in our brains for along time and the most current belief is that its something to do with the activity of the neurons and the way there activated so If you do a specific thing a lot those neurons are being used in a specific way in a relatively specific order so you begin to remember. Its something like that (correct if I am wrong).

 

[The Dagda]

It's actually more or less infinite. There is only a limit of how long we live to how much information we can potentially store, bits don't fall out if we get full up, if that were even remotely possible. So given the massive potential of those 100 trillion brain cells to make almost an infinite number of memories, as far as we know talking about brain capacity in terms of a computer is meaningless. Our brains are more sophisticated than binary, they use fuzzy logic, and a much more sophisticated version of that. Who knows perhaps a quantum computer might be able to keep up with us.

Some people with photographic memory must have huge brain capacity because of the resolution of the images they have so as a stab in the dark it could be as much as hundreds of thousands of terrabytes.

Some people have a natural photographic memory, but practically anyone can train themselves to have one. A good example is Derren Brown who wasn't born with a photographic memory, or the world memory champion who started learning about memory because his was particularly bad. The brain is dynamic, it is far from hard wired and it is practically infinitely more flexible than 1 and 0.

 

[Veovis]

Everything in the brain is about memory. Its not just what you can consciously remember.
When we are born (even before), our nervous system learns the succesfull neural impulses and memorices them for future use. We walk by memory, we remember to avoid danger, our brain remembers how to iterpret the optical nerve input, and how to breath, etc...
So if we are to measure the amount of memory, we should count for all nerve-nerve possible interactions, in spatial, frequency, and maybe molecular domain.

I don't think that memory is something static tha we can account for every time. Consider forgetting and re-remembering, or consider creativity: the asocciation of memories. How do we count this "hidden" posibilities?
What must be measured? Quantity, quality, or both?

PD: sorry for my spelling.

 

[The Dagda]

To be frank the brain is so mysterious atm that the answer to the OPs in anything more than a totally speculative manner is little more than a fairy tale based on what if they could be compared. They can't and there is no possibility of us ever running out of space, as the brains hardware is dynamic, unlike a PC's which has to be updated every 5 years or so. If you are talking about brute forcing information into the brain by some odd means all in one go, then it's anyones guess how many terabytes you could get in before you turned the person into a gibbering mental patient.

 

[confused2008]

To be frank the brain is so mysterious atm that the answer to the OPs in anything more than a totally speculative manner is little more than a fairy tale based on what if they could be compared. They can't and there is no possibility of us ever running out of space, as the brains hardware is dynamic, unlike a PC's which has to be updated every 5 years or so. If you are talking about brute forcing information into the brain by some odd means all in one go, then it's anyones guess how many terabytes you could get in before you turned the person into a gibbering mental patient.

I did not in my original post mean to offend anyone. I understand the workings of the mind and memory. I was just offering an educated guess. In reference to the above quote I myself suffered a mild stroke a few years ago and have relapses in my memory. I have had bad episodes which turn me into a "gibbering mental patient" but afterward i have drawn stuff that looks like it came out of a encyclopedia. So before I could have been brute forcing information into my brain which could be thousands apon thousands of terabytes if for example you looked at a brain as a computer.

 

[The Dagda]

I did not in my original post mean to offend anyone. I understand the workings of the mind and memory. I was just offering an educated guess. In reference to the above quote I myself suffered a mild stroke a few years ago and have relapses in my memory. I have had bad episodes which turn me into a "gibbering mental patient" but afterward i have drawn stuff that looks like it came out of a encyclopedia. So before I could have been brute forcing information into my brain which could be thousands apon thousands of terabytes if for example you looked at a brain as a computer.

Oh no I'm not offended nor is anyone else, it's just a fact that you can't compare the two systems because of hardware differences. We need to make it clear that not only does the brain not store information in the same way, but it doesn't even store it as a series of 1's and 0's and. In fact one of the most intriguing questions is how it does so at all.

 

[confused2008]

Ok ok you got me.
(holds up hands and surrenders)
But as a last point it does make you curious about those movies when a person' brain is downloaded into a computer.
I do understand that it is fiction and this is a place not to be discussing fiction just fact.

 

[The Dagda]

Ok ok you got me.
(holds up hands and surrenders)
But as a last point it does make you curious about those movies when a person' brain is downloaded into a computer.
I do understand that it is fiction and this is a place not to be discussing fiction just fact.

Not at all, you just have to be careful to distinguish what is fiction and what is fact. If you had to have physical proof for everything then the beyond the standard model area of the forum wouldn't exist I suspect. It's fine to speculate, in SG1 for example Colonel O'niel has the knowledge of the ancients downloaded into his brain, from which he is able to construct a gate to another galaxy and save humanity with some fancy electronics. Problem is the information is so vast, it leaves no room for anything else, so he goes slowly ancient and slowly his mind begins to break down.

 

[confused2008]

Not at all, you just have to be careful to distinguish what is fiction and what is fact. If you had to have physical proof for everything then the beyond the standard model area of the forum wouldn't exist I suspect. It's fine to speculate, in SG1 for example Colonel O'niel has the knowledge of the ancients downloaded into his brain, from which he is able to construct a gate to another galaxy and save humanity with some fancy electronics. Problem is the information is so vast, it leaves no room for anything else, so he goes slowly ancient and slowly his mind begins to break down.

Like a computer when it needs to defrag. LOL

 

[Cincinnatus]

The brain does have an information capacity; you can measure it in bytes. Any physical system has some finite number of states which it can be in. This limits the amount of information that can be coded; for the same reason that there are only a finite number of books in Borges' Library of Babel*. This number is very large but certainly not infinite.

* http://en.wikipedia.org/wiki/The_Library_of_Babel

 

[The Dagda]

No one disputes that you could find it in theory, the problem is without knowing how the hardware works, how could you possibly guess?

 

[Cincinnatus]

No one disputes that you could find it in theory, the problem is without knowing how the hardware works, how could you possibly guess?

You do experiments! You can have people memorize lists, learn skills, recall experiences etc. You can measure their performance on all of these. The question "what is the information capacity of the brain" is not the question you mean to ask. What you want to know is: "how many things can be held in long term memory?" This is a question that is amenable to psychological experimentation.

 

[Proton Soup]

i searched for a while, but didn't find the answer to the data storage capacity of the brain. but if you look under information theory, there is a bit of research into channel capacity of input/output nerves of the brain. some things are kind of low, like a paper estimating the data output capacity of the hand at around 150 bits/sec.

 

[jreelawg]

A psychology professor once explained memory to me as pathways that are made in the brain through experience. Imagine a giant field of grass. If you walk across it, you trample the grass beneath your feet. The more you follow the same path, the more pronounced the path is. Paths that are only followed once aren't pronounced, and over time, the grass can grow back and the path becomes hard to see. In our brains, the pathways are neural connections. I'm not sure how much of this metaphor translates into reality, and what it means in terms of storage capacity.

 

[Cincinnatus]

i searched for a while, but didn't find the answer to the data storage capacity of the brain. but if you look under information theory, there is a bit of research into channel capacity of input/output nerves of the brain. some things are kind of low, like a paper estimating the data output capacity of the hand at around 150 bits/sec.

Be very wary of those "results". In order to make those information theoretic calculations you need to assume that you know the neural representation that is being used. This is not something that is known (or agreed upon anyway).

For example, let's say you didn't understand English and someone gave you a block of text without any spaces in it. Then say you wanted to calculate how much information is contained in the text. You would immediately notice that all the symbols were drawn from the same alphabet. So a reasonable guess as to the information capacity of the text could be 26^N where N is the number of characters and 26 is the number of letters in the alphabet.

However, this would be much too high. In English, information is not conveyed by single letters. Rather, information is conveyed by words. If you really wanted to know how much information is in the text you would need to be counting words, not characters.

Why stop at words though? Counting words is certainly a more reasonable approach to quantifying information in text than counting characters... Maybe, counting sentences would be even better? Or perhaps there is some higher order linguistic structures that could be invoked.

This is analogous to the situation in neuroscience. The difference being that in neuroscience, we don't even know the alphabet being used. Any article that makes claims like "cells transmit X bits per second" is making assumptions about the nature of the neural code which may or may not be warranted.

 

[Winzer]

You do experiments! You can have people memorize lists, learn skills, recall experiences etc. You can measure their performance on all of these. The question "what is the information capacity of the brain" is not the question you mean to ask. What you want to know is: "how many things can be held in long term memory?" This is a question that is amenable to psychological experimentation.

I mean total capacity. So not only long term memory, but short. There must be a finite maximum amount of memory able to be used. Just like buffer memory.

 

[The Dagda]

I mean total capacity. So not only long term memory, but short. There must be a finite maximum amount of memory able to be used. Just like buffer memory.

Is there or is it dynamic? After all what is the brain capacity of a neonate? Now a teenager? And Adult? Isn't the hardware being constantly added to, unlike a computer which tends to remain static unless you plug something in.

 

[Winzer]

Is there or is it dynamic? After all what is the brain capacity of a neonate? Now a teenager? And Adult? Isn't the hardware being constantly added to, unlike a computer which tends to remain static unless you plug something in.

A good question. But what about a fully developed brain(this is supposed to be around 25, don't quote me on this though)?

 

[JorgeLobo]

Agree - theories and models are just speculation unless they are validated. Would like to see the validation here.

 

[Human Bean]

Interestingly, on the defrag theme, there is a famous clinical case of someone who was unable to forget, i mean anything, just remembered everything that was processed beyond sensory registration. They actually had to learn how to forget by act of will...check out Alexander Luria's famous book - The mind of the Mnemonist, or I think Oliver Sacks wrote about a similar case too.

 

[Raizy]

This is kinda off topic, but if our brains are so great why do we always have to study to retain information? I just learned the next section from my math textbook yesterday, and if I don't review within the next couple of days that stuff is *poof*.

 

[mandh32208]

Is is possible to quantify how much "space" a human brain has? Kind of like in terms of hard-drive space?
I am sure this depends on the person.

I think it is. It seems to be kind of the same concept. With a computer there is a limit to how much memory the hard drive can handle. It's kind of like with my fiancé. If you ask me, I think he could best be compared to an HP with a AMD turon x2 processor with a 400GB Hard drive, and an 8 GB Ram (I know I know, it doesn't exist, but you never know, with brains like his in people roaming the Earth (see DXM post), it might come to pass sooner or later. But yea, I think that is a very good way to compare the capacity of a brain to something that has relatively the same kind of concepts.

 

[jwlm88]

This is kinda off topic, but if our brains are so great why do we always have to study to retain information? I just learned the next section from my math textbook yesterday, and if I don't review within the next couple of days that stuff is *poof*.

In my opinion information that is unused is erased. The structure of the brain is elastic so that it can change into new... for a lack of a better word "form". Someone jokingly talked about "Defraging" your brain. That is exactly why the brain is so elastic. Humans have large wrinkly brains to store massive if not infinite amounts of data. However, such data would be catagarize by the amount of times the data is accessed giving the used data preference over unused data. Therefore unused memories such as early childhood or what you ate for lunch a week ago Friday is deleted. That is my personal theory.

 

[jsgruszynski]

These kind of number has no meaning as several people have pointed out.

Here's a human specification that completely flummoxes these comparisons or metrics:

The maximum information and data rate of the human retina is 500 Kbits/second for B&W and 600 Kbits/second for color.

http://en.wikipedia.org/wiki/Retina#Physiology (see end of section)

This is due to the fact that 1) the retina detects only contrasts in space and time - it's been found to be a neural net that performs entropy filtering - and only the filtered result is sent to the optic nerve, 2) the high resolution portion of the eye is the fovea which is a very small portion of the retinal area, and 3) the entire "field" of vision is collected by scanning the fovea over the field of view by fixational and saccadic movement that collects only a portion at a time and thus the "full visual field" information rate is even slower than the above numbers! The brain patches these together to give the illusion of a full field of view. In short, most of the information that hits the retina as light is simply thrown away - to the tune of 99.9% or more.

To put this in perspective, the worst web cams have far higher performance than this:

640x480x30fps = 9.12 Mbits/second for B&W and 3x this number for color or 100x higher data rate. This is a sucky web cam.

This suggests the entire mechanism of computing by the human brain is completely and utterly different from a computer.

In fact, we all live a fraction of a second in the past from reality because of this low information rate - whatever you see in any given moment actually happened a second ago and it's only catching up to your consciousness right now when you notice it.

There are cognitive theories that say that what we see is simply an internally created simulation that is corrected by low-information-rate hints from our eyes. Learning how to draw or paint involves learning ways to override these simulations so you can "see" and draw what you are actually seeing rather than what your brain simulates as the objects it has recognized. Learning to be truly "scientific" in the use of empirical reality is much the same.

 

[jsgruszynski]

In my opinion information that is unused is erased. The structure of the brain is elastic so that it can change into new... for a lack of a better word "form". Someone jokingly talked about "Defraging" your brain. That is exactly why the brain is so elastic. Humans have large wrinkly brains to store massive if not infinite amounts of data. However, such data would be catagarize by the amount of times the data is accessed giving the used data preference over unused data. Therefore unused memories such as early childhood or what you ate for lunch a week ago Friday is deleted. That is my personal theory.

All memories in the brain are associative. There's an essential aspect of "use it or lose it" because being associative automatically has a "defragging" algorithm built into it, except that it's implicit rather explicit like a reference count or such would require. This allows unneeded associations or memories to be gradually worn away and purges in direct proportion to their necessity.

I would say the brain can store infinite amounts of data because associative memories are built upon existing similar metaphors. Lakeoff and Johnson call the base layer of associations "embodied metaphors" which are constructed in infancy based on physically interacting with our environment. All the basic metaphors we used to describe just about everything comes from these. That includes "Cause and Effect", "Things as Containers", "Things as Contents of Containers", "Things that can be Pushed or Pulled", "Things that Cause other Things as Effects". Lakeoff and Johnson found that most of our every day thinking and speaking is based on these core embodied metaphors as are the ways we use to remember things (generally by analogy to these).

The limitation on memory then is that our memories are mostly only things we can compare or imagine in terms of these metaphors or metaphors that trace back to the embodied metaphors. That, unfortunately leaves out a lot things. For example, we have trouble with remembering perfectly random sequences if there are no mnemonics to associate with them. Phone numbers were made to be 7 digits because the limit to what we can remember as a random sequence is 5 +- 2 items. We can only remember more if we can associate some existing memory as a metaphoric link.

An extreme example (which relates to perception of reality itself also) is implied by Richard Dawkins talk:

video.google.com/videoplay?docid=1223148353177749002

So we can't even conceptualize quantum mechanics in part because we are evolved to be Middle World creatures so imagine all the things that can't be remembered because they can't be conceptualized in the first place due to a lack of cognitive metaphor. In fact the central of metaphor is a blindspot itself.

Stephen Wolframs New Kind of Science talks about computational equivalent in this respect - if Dawkins sand dune is computationally equivalent to human cognition, what does that say about perception of the universe?

http://mitworld.mit.edu/video/149

 

[Blenton]

These kind of number has no meaning as several people have pointed out.

Here's a human specification that completely flummoxes these comparisons or metrics:

The maximum information and data rate of the human retina is 500 Kbits/second for B&W and 600 Kbits/second for color.

http://en.wikipedia.org/wiki/Retina#Physiology (see end of section)

This is due to the fact that 1) the retina detects only contrasts in space and time - it's been found to be a neural net that performs entropy filtering - and only the filtered result is sent to the optic nerve, 2) the high resolution portion of the eye is the fovea which is a very small portion of the retinal area, and 3) the entire "field" of vision is collected by scanning the fovea over the field of view by fixational and saccadic movement that collects only a portion at a time and thus the "full visual field" information rate is even slower than the above numbers! The brain patches these together to give the illusion of a full field of view. In short, most of the information that hits the retina as light is simply thrown away - to the tune of 99.9% or more.

To put this in perspective, the worst web cams have far higher performance than this:

640x480x30fps = 9.12 Mbits/second for B&W and 3x this number for color or 100x higher data rate. This is a sucky web cam.

This suggests the entire mechanism of computing by the human brain is completely and utterly different from a computer.

In fact, we all live a fraction of a second in the past from reality because of this low information rate - whatever you see in any given moment actually happened a second ago and it's only catching up to your consciousness right now when you notice it.

There are cognitive theories that say that what we see is simply an internally created simulation that is corrected by low-information-rate hints from our eyes. Learning how to draw or paint involves learning ways to override these simulations so you can "see" and draw what you are actually seeing rather than what your brain simulates as the objects it has recognized. Learning to be truly "scientific" in the use of empirical reality is much the same.

Or it could suggest that we have a far, far superior form of image compression since our brains only receive a relatively low amount of data compared to our digital equivalents. I don't know about you but my eyes receive much more detailed images than any camera can capture.

 

[jsgruszynski]

Or it could suggest that we have a far, far superior form of image compression since our brains only receive a relatively low amount of data compared to our digital equivalents. I don't know about you but my eyes receive much more detailed images than any camera can capture.

You're quite right. It certainly does suggests image compression already.

Except that it's lossy. It's called semiotic generalization and naming. We call anything that is vaguely apple-shaped and red simply an "apple". That's an enormous amount of information compression. It completely throws away any information about a particular apple (we don't care much for Apple-rights so this isn't much of an issue of "every apple is an individual"). The very basis of brain computation seems to be based on this type of compression. Descarte should have said: "I generalize and name, therefore I am" - my Latin sucks so I can't translate that.

This is very different from a digital computer which represents things abstractly but doesn't have the gradation of representation that the human brain has in this respect. It can't bootstrap itself from it's creation nor can it bootstrap itself in a novel situation its programming didn't anticipate. The human brain can do both of those.

You can't compress below pure information without this discarding of information like this. The bandwidth limits of the retina are so low that information-wise it doesn't seem one could ever "catch up" to achieve a "real-time feed" from the world as we know it in a computer system. The numbers just don't work out. That's really the point - we aren't connected to the outside world with anything close to 100% fidelity, except by possible tricks like internal simulation.

When you back these information rates into "smallest noticeable spatial change" and the like, it fits well with known limits described experimental psychology in various UI references by Card and Moran.

For example the net information rate (information != data) from outside environment through the visual system to consciousness is only 3-4 bits per second in terms of distinct and separable information events. Some of this is due to the limits on short-term memory for non-associative (pure information) being limited to 5+-2 states. It pops off the FIFO quickly. Thankfully the world and our "codebook" for the world offer a lot of redundancy for associative linking (which is sometimes known as "chunking"). Think of it in terms of being a one-time pad for all the common things we can semiotically generalize to. There's also the question of how do you bootstrap the coding?

In most designed compression codes there is knowledge of the redundancy on both sides (sender and receiver). For natural language text there are known redundancies - the "Wheel of Fortune" trick or crytographer's first pass using ETAOANIRSH... For video compression like MPEG4, the fact that the human eye detects nothing faster than ~200 ms is used to throw out information (that's the retina's compression at work). But if you are talking about bootstrapping for the redundancies of the external environment, how does that happen? Essentially this is the same problem of how do you distribute a one-time pad without either side knowing a common language or having a common context.

The likely means is "childhood development" - where we accumulate the external environment's redundancy through direct interaction and learning from the starting point of quasi-Tabula-Rasa (it's prone to generalize-name and then synthesize so it's not pure blank). This also fits with Wolfram's idea that there are systems with high computational complexity for which the fastest means of simulating their results (akin to the halting problem) is to use the real thing and let it play in real-time because no simulation will run faster.

One of the exercises from "Drawing with the left side of your brain" (it's probably not "left" but "lower" but that's the title) that illustrates this. People without art training, about the time than childhood development predicts the onset of "abstract thinking", people tend to lose the ability to "draw naturally" and their drawings tend to have a common theme: drawing things that have geometric abstractions tend to be drawn more like the abstraction than like the actual visual field view of the object. In other words they draw the abstraction and not what they are actually "seeing" because as a artist would describe it, "they haven't learned to 'see'" or actually "see literally" rather than "see symbolically". This traces back to pre-Renaissance, pre-perspective drawing which often had people drawn in size proportional to their social standing rather than literal size - symbolic drawing. Another way of saying it: drawing an internal simulation of reality rather than reality as it empirically exists.

Other references for this model/framework are Jeff Hawkins (co-founder of Palm) and Dan Dennett:

http://www.ted.com/index.php/talks/jeff_hawkins_on_how_brain_science_will_change_computing.html

http://www.ted.com/index.php/talks/dan_dennett_on_our_consciousness.html