mr@isrnix.UUCP ( Michael Regoli ) (06/11/84)
Has anyone converted human memory capacity into bits and bytes?
That is to say, is there an equivalent of megabytes to an average
human being's brain capacity?
--
Michael Regoli { ihnp4|inuxc|pur-ee }!isrnix!mr
Institute for Social Research
Indiana University - Bloomingtonrbg@cbosgd.UUCP (Richard Goldschmidt) (06/11/84)
This is not a simple issue. No one has conclusively demonstrated a limit
to the long term storage capacity of the human brain ("you learn something
new every day!"). I have heard one estimate that the information processing
capacity of a single neuron approaches that of a Cray-1, and there are
10^12 neurons in the human brain...ab3@stat-l (Rsk the Wombat) (06/12/84)
Not sure about this, but check "The Dragons of Eden" by
Carl Sagan...I seem to recall reading an off-the-cuff estimate in there
somewhere.
--
Rsk the Wombat
UUCP: { allegra, decvax, ihnp4, harpo, teklabs, ucbvax } !pur-ee!rsk
{ allegra, cornell, decvax, hplabs, ihnp4, ucbvax} !purdue!rskrkp@drutx.UUCP (Pierce) (06/12/84)
>> Not sure about this, but check "The Dragons of Eden" by >>Carl Sagan...I seem to recall reading an off-the-cuff estimate >>in there somewhere. (I can't pass this one up.) Did Carl Sagan say there were "billions and billions" of storage cells in someones brain? :-) No Flames, Pleeeeeez!!! Russ Pierce drutx!rkp
gam@proper.UUCP (Gordon Moffett) (06/13/84)
> From: mr@isrnix.UUCP ( Michael Regoli ) > Organization: ISR - Indiana University > > Has anyone converted human memory capacity into bits and bytes? > > That is to say, is there an equivalent of megabytes to an average > human being's brain capacity? In "The Dragons of Eden" (pg 42-43), Carl Sagan arrives at a figure of: 10 trillion to 100 trillion bits, which is 1.25 million to 12.5 million megabytes, or 1.25 to 12.5 gigabytes. (... assuming 8-bit bytes).
rcb@fortune.UUCP (Robert Binstock) (06/13/84)
-------- I believe there are aprroximately 10 to the 9th neurons in a human brain, if that's of any help. Add in the glial cells (there is some debate about their function) and it comes to 10 to the 10th. Bob Binstock
tower@inmet.UUCP (06/15/84)
#R:stat-l:-10100:inmet:8000006:000:277
inmet!tower Jun 14 11:18:00 1984
Re: Carl Sagan and Brain Capacity Estimates
I don't know about "Dragons of Eden", but he definitely gave one
on the air during the PBS Cosmos series. You might check that book
as well ("Cosmos" by Carl Sagan).
-len tower {ihnp4,harpo}!inmet!tower Cambridge, MAgam@proper.UUCP (Gordon Moffett) (06/19/84)
A correction to my previous article on this subject. It has been
pointed out to me that 1 million megabytes does not a gigabyte make.
Thus, the brain may be presumed to have ~1000 gigabytes of memory,
rather than ~1 gigabyte.
My apologies for the error.
--
Gordon A. Moffett
{ hplabs!nsc, decvax!sun!amd, ihnp4!dual } !proper!gamrpw3@fortune.UUCP (06/22/84)
#R:isrnix:-18600:fortune:9700009:000:5219
fortune!rpw3 Jun 21 23:40:00 1984
Summary:
Human brain store ~1000 gigabytes?? Come on! Humans max out well below
80 bits/sec, so no more than ~10-30 Gbyte is needed... (so maybe we got
some spares, huh?)
Discussion:
Actually, quite a bit of work has been done on this by quite a few
experimental psychologists. The classic paper on human "bandwidth"
is, of course,
G. A. Miller, "The Magical Number Seven, Plus or Minus Two:
Some Limits on Our Capacity for Processing Information",
The Psychological Review, 1956
Miller defines "processing capacity" in terms of "absolute judgments",
i.e., the ability to discriminate among stimuli (e.g., "which of the N
tones is this tone?"). The information per trial (e.g., correctly picking
one of eight tones is 3 bits) is adjusted for error rate:
"...the observer is considered to be a communications
channel... The experimental problem is to increase the
amount of input information and to measure the amount
of transmitted information. If the observer's absolute
judgements are quite accurate, then nearly all the input
information will be transmitted and will be recoverable
from his responses. If he makes errors, the transmitted
information may be considerably less than the input. We
expect that, as we increase the amount of input information,
the observer will begin to make more and more errors; we
can test the limits of accuracy of his absolute judgaments.
If the human observer is a reasonable kind of communication
system, then when we increase the amount of input information
the transmitted information will increase at first and will
eventually level off at some asymtotic value. This asymtotic
value we take to be the 'channel capacity' of the observer;
it represents the greatest amount of information that he can
give us about the stimulus on the basis of absolute judgements..."
Plotting many previous experimenters' data (plus some of his own), he
shows that the human ability to discriminate stimuli for uni-dimensional
stimuli (pitch only, or brightness only, or linear position only) is
about 2.6 bits, or correctly picking one of six equally likely choices.
The highest capacity channel observed was about 3.5 bits (10-15 choices),
when picking pointer positions off a line. [Hmmm... like interpolating
between gradations on a meter stick.] The lowest capacity was for
taste intensities, about 1.9 bits.
With multidimensional stimuli (i.e. pitch AND loudness AND duration, etc.),
channel capacity goes up, but even with 6-8 dimensions the information
per decision was not more than about 7 bits. By grouping items into
sequences, the total information increases, although the information
per item goes down, so that short-term memory recalls of 40 bits or so
were demonstrated (with the aid of considerable re-coding).
The really important contribution of the paper, I am skipping over --
the ability of humans to "re-code" or "chunk" their input, so as to handle
more data. (In the memory test above, the "re-coding" was to use octal,
hex, and base-32 numbers to remember strings of binary digits.)
[Note: this paper has been used as a standard reference to show why, for
example, function keys on a keyboard should be clustered in groups of
four or five.]
Instead, look at what this says about total human bandwidth. As an UPPER
limit, let us assume that we can correctly and consistently and continually
absorb and process input stimuli at 8 bits per event (higher than ANY shown
in the lab!) at 10 events per second (faster than one event per reaction-time).
The would put our input processing at 80 bits/second (which is FAR too high!).
Note that this has little to do with reading speed, since estimates of
the information content of English range as low as 1.1 bits/word, once
the contextual environment is built up. (Try cutting every third word
out of newspaper stories... you'll be surprised how much is left!)
Also, due to re-coding, we are constantly editing our input to maximize
the "quality" of those bits. (See Frank Herbert's "Destination Void" for
a fascinating discussion of consciousness as mediator of perception. Watch
your own mind sometime to see how things in the environment come into your
awareness and disappear again, all the time.)
Again, 80 b/s is a somewhat excessive upper limit. Try reading and
REMEMBERING 10 char/sec of random text, continuously! Even so, at 24 hours
a day (no sleep?), 100 years per life, remembering everything perfectly,
one needs only about 30 gigabytes of long-term memory. Fits on a couple a
Betamax cassetees, easy! [Note: 2 bits/Hz, 75% utilization of each scan line,
a good Reed-Solomon code on top of rate-1/2 Viterbi, gives over 1.5 Gbyte
per hour of play time ==> ~3.5 six-hour tapes.]
(Actually, this makes the science-fiction ideas about personality/learning
transfer seem almost attainable, if only...)
In fact, the actual data rate and storage are probably far less. I would
dare say less than ONE Beta tape! The trick is in coding ("chunking") the
data. Anybody want to try and Huffman-code a lifetime?
Rob Warnock
UUCP: {ihnp4,ucbvax!amd70,hpda,harpo,sri-unix,allegra}!fortune!rpw3
DDD: (415)595-8444
USPS: Fortune Systems Corp, 101 Twin Dolphin Drive, Redwood City, CA 94065scw@cepu.UUCP (06/26/84)
In article <3663@fortune.UUCP> rpw3@fortune.UUCP writes: >Summary: > >Human brain store ~1000 gigabytes?? Come on! Humans max out well below >80 bits/sec, so no more than ~10-30 Gbyte is needed... (so maybe we got >some spares, huh?) > >Discussion: > >Actually, quite a bit of work has been done on this by quite a few >experimental psychologists. The classic paper on human "bandwidth" >is, of course, > > G. A. Miller, "The Magical Number Seven, Plus or Minus Two: > Some Limits on Our Capacity for Processing Information", > The Psychological Review, 1956 > >Miller defines "processing capacity" in terms of "absolute judgments", >i.e., the ability to[...]ightness only, or linear position only) is >about 2.6 bits, or correctly picking one of six equally likely choices. >The highest capacity channel observed was about 3.5 bits (10-15 choices), >when picking pointer positions off a line. [Hmmm... like interpolating >between gradations on a meter stick.] The lowest capacity was for >taste intensities, about 1.9 bits. > What a bunch of bullshit! Think about it, how much information has to be processed to make these decisions? I can pick a person that I know out of a crowd almost instantly. How much information was processed to do this? A whole lot more than 8 bits/sec I'll bet. I think that someone is(was) confusing information processing with decision making capibility. How much information is processed in how much time by a batter hitting a fast ball? Could you write program to do it? (retorical question). >With multidimensional stimuli (i.e. pitch AND loudness AND duration, etc.), >channel capacity goes up, but even with 6-8 dimensions the information >per decision was not more than about 7 bits. By grouping items into >sequences, the total information increases, although the information >per item goes down[...]the time.) > >Again, 80 b/s is a somewhat excessive upper limit. Try reading and >REMEMBERING 10 char/sec of random text, continuously! Even so, at 24 hours >a day (no sleep?), 100 years per life, remembering everything perfectly, >one needs only about 30 gigabytes of long-term memory. Fits on a couple a >Betamax cassetees, easy! [Note: 2 bits/Hz, 75% utilization of each scan line, >a good Reed-Solomon code on top of rate-1/2 Viterbi, gives over 1.5 Gbyte >per hour of play time ==> ~3.5 six-hour tapes.] > >(Actually, this makes the science-fiction ideas about personality/learning >transfer seem almost attainable, if only...) > >In fact, the actual data rate and storage are probably far less. I would >dare say less than ONE Beta tape! The trick is in coding ("chunking") the >data. Anybody want to try and Huffman-code a lifetime? > >Rob Warnock > >UUCP: {ihnp4,ucbvax!amd70,hpda,harpo,sri-unix,allegra}!fortune!rpw3 >DDD: (415)595-8444 >USPS: Fortune Systems Corp, 101 Twin Dolphin Drive, Redwood City, CA 94065 The problem here is that people don't remember 'text' they remember information. The amount of information contained in a human brain is *VERY* much larger than you would suspect. How much information is contained in a mental picture of say, your spouse? Probably several thousand bits of color/spacing of features /expressions/marks/habits/smells/sizes &tc &tc. Most people know several tens thousands of words , how many bits to quantify all of the manifold meanings encoded in a word (I mean things like implied color, size, weight, actions of named object)? Think about it, that Beta tape only holds ~~2 hours of partial visual/audio input. -- Stephen C. Woods (VA Wadsworth Med Ctr./UCLA Dept. of Neurology) uucp: { {ihnp4, uiucdcs}!bradley, hao, trwrb, sdcsvax!bmcg}!cepu!scw ARPA: cepu!scw@ucla-cs location: N 34 06'37" W 118 25'43"
dya@unc-c.UUCP (06/28/84)
References: cepu.294
>The problem here is that people don't remember text they remember information
Whoever said that the human brain was binary, or representational, or
anything else. I think that even cepu!scw ( a neurologist ? ) would have
to concede that some sort of behavioural "engine" might trade off sheer numbers
of bits for speed. If you're looking for high speed data acquisition, don't
ask human neurological tissue to carry it; isn't it extremely slow ?
Aside from exhausting the subject, I think that the question that "How
many Crays does a human brain emulate, or how many 6665AL20's does it take
to store a brain's worth of information" is quite meaningless. We understand
very little (but are making rapid advances) about the brain at the cellular
level. It's like Carl Sagan's estimate of other planets like ours, or trying
to use an Atari 400 to do oil well modeling. The information is so poor that
the results are truly meaningless.
-dya-gary@mit-eddie.UUCP (Gary Samad) (07/06/84)
><
Hear, hear, Stephen! I've heard that 8 bit per second malarky before.
How many bits does a single picture represent? At least 16000 (2 bytes
times 1000 words :-) and it doesn't take me 4 1/2 hours to appreciate
one :-)
Gary Samad