
Ask HN: What is the size of human memory? - kashif_hn
Is it in GB, TB or still higher? Is it possible to exactly calculate it?
======
tokenadult
The main problem with human memory is that read operations are also write
operations.

[http://koehlerlaw.net/2010/09/on-human-memory-and-
eyewitness...](http://koehlerlaw.net/2010/09/on-human-memory-and-eyewitness-
testimony/)

<http://faculty.washington.edu/eloftus/Articles/sciam.htm>

[http://agora.stanford.edu/sjls/Issue%20One/fisher&tversk...](http://agora.stanford.edu/sjls/Issue%20One/fisher&tversky.htm)

[http://townhall.com/columnists/jacobsullum/2011/08/31/your_l...](http://townhall.com/columnists/jacobsullum/2011/08/31/your_lying_eyes_how_fallible_memories_send_innocent_people_to_prison/page/full/)

Human memory is continually being reshaped, and is not a reliable archive of
anyone's experience.

The other problem with the human brain's large capacities in general is that
bandwidth to and from the brain constrains the brain's interaction with the
environment. I have read (I'm sorry I don't remember the source off-hand) that
human sensory organs have a huge information capacity, and the human brain has
a huge capacity both to process and to store information, but the nervous
system's connections between sensory nerves for input or between motor nerves
for output are strictly limited in bandwidth, so you always have to ignore
much of what you could perceive or do. A really good book about the built-in
capacity for human self-deception is The Folly of Fools: The Logic of Deceit
and Self-Deception in Human Life by Robert Trivers,

[http://www.amazon.com/The-Folly-Fools-Deceit-Self-
Deception/...](http://www.amazon.com/The-Folly-Fools-Deceit-Self-
Deception/dp/0465027555)

which is full of interesting information about limitations of the thinking of
all organisms, especially human beings.

------
seiji
Memories aren't discrete entities. Your brain isn't linearly addressable like
our computer abstractions. At best, the answer is combinational in the number
of synaptic connections in certain parts of the brain. At worst, the answer is
essentially "unlimited."

How do you quantify the storage size of petrichor? A bad kiss? A good morning
after? Episodic memory is a bitch.

------
alok-g
The answer changes significantly if the question is phrased as "How many bits
of information can a human possibly _recall_ (if given enough time)?"
Estimates of this from a few studies are at about merely 10-30 MB [1].

[1] www.amazon.com/Ai-Tumultuous-History-Artificial-
Intelligence/dp/0465001041/

------
matury
scholars speculate that the human brain might be around 2 to 3 Yottabytes
others says is unknown. In My personal opinion there's no table to measure
human brain storage capacity, since is an organic drive but perusing a
measurable table, they should add one more variant to the table - Humabyte -
representing human storage capacity above all known table up to date.

~~~
kashif_hn
Since the size of bit is known so we have KB, MB, GB and so on. However if we
are not able to measure human brain storage capacity on the basic level (like
bit in case of computers) how can we define a Humabyte?

~~~
matury
according to this "Harvard cracks DNA storage, crams 700 terabytes of data
into a single gram" They claim that each GRAM of DNA has an equivalent of 700
TB that's not counting the brain storage capacity or the organs storage
capacity (each organ has tremendous storage capacity, and it seems it can be
access by the nerve system of any human host. In transplant of hearts, livers,
lungs, etc., the patient can describe what the original human host was like in
terms of personality, memories, and actions) Taking all of this information,
scholar should be able to calculate a raw average of the human storage
capacity - Humabyte.

------
kashif_hn
I have heard somewhere that human memory size is not known till date.

~~~
byoung2
[http://www.scientificamerican.com/article.cfm?id=what-is-
the...](http://www.scientificamerican.com/article.cfm?id=what-is-the-memory-
capacity)

 _The human brain consists of about one billion neurons. Each neuron forms
about 1,000 connections to other neurons, amounting to more than a trillion
connections. If each neuron could only help store a single memory, running out
of space would be a problem. You might have only a few gigabytes of storage
space, similar to the space in an iPod or a USB flash drive. Yet neurons
combine so that each one helps with many memories at a time, exponentially
increasing the brain’s memory storage capacity to something closer to around
2.5 petabytes (or a million gigabytes)_

That said, I don't think you can make a simple comparison between the bits in
a computer and the memories in a human brain. I think that the human brain
beats the computer in terms of raw storage capacity, since a single brain can
continue accumulating data for a lifetime without needing an upgrade, but the
computer is more efficient at storing the bare minimum. For example, a
computer can store a simple concept like a picture of a plate of spaghetti in
a 3KB file. The human brain might store that image, along with a memory of the
smell, taste, and emotions related to spaghetti. It might also connect that
memory to different places you've eaten it, and how they compared. In a
computer system, it would be impractical to store and retrieve this extra
metadate, but the brain seems to be able to.

I remember learning in a college class on cognitive science that some
scientists believe that human memory is permanent, in that long term memories
don't get erased, they just get harder to access. It makes sense that when
something is on the tip of your tongue and you remember it later on that it
was probably just a slow query.

