I can remember 16+ digits, it all depends on how you group them and relate them to one another.

Besides, everyone can remember loads of tidbits, otherwise you wouldn't be able to communicate. It's all patterns, IMHO.

Actually... I remember doing an experiment in college for a class called "Human Factors" where we looked at this very phenomina. And what we found is that its a combination of both items.

7 digits is too hard to remember if not broken into groups. So groupings of 3 to 4 is the most efficient.

However, you can't just string together many groups of 3 to 4 numbers have people then remember 15, 18, or 22 digits either.

So the result is that the most you can remember is 3 to 4 groups of 3 to 4 numbers.

> Are human beings only capable of holding
> between 5 and 9 pieces of information in their
> heads at once? That's only 2.5 bits of
> information.
That's not 2.5 bits of information.

The number of pieces can be represented in 2.5 bits of information. The pieces of information themselves can be as small as 1 bit each (still 7 bits of information), or as large as 20 bits each -- let's say, the numbers 1 million, 2 million... to 7 million -- making 140 bits of information.

Though the numbers "(1-7) million" could probably also be remembered as one piece of information, leaving 140 bits of information right there with room to spare.

Not sure where I'm going with this but your statement there was not really saying anything.

It's the same argument.

Which is easier to remember? My telephone number..

510-307-8234

.. or my email address?

jatwood(at)codinghorror.com

Let's not forget the teachings of Dale Carnegie...

In the memory lessons of the class, we're taught that through relating mental imagery and the memorization of a few key concepts, we can actually store 42+ units of information (he claims infinite, but I've never seen more than 42)

The process is his "one-run, two-zoo" paired listing...

For each paired list, the person visualizes a scenario in their head involving the number/item they need to remember.

I can personally remember up to 21 groups of numbers (3-4 in size) for rapid recall... But I haven't been practicing nearly long enough.

> So which is it? Can people remember 7 digits at >once? Or are they really remembering chunks of 3 >digits, 3 digits, and 4 digits?

I remember in a cog sci class back in college the professor gave a great presentation. He started by saying a bunch of random of words and asked us to remember them (without writing them down). Then he asked us to recite back as a class as many words as we can. Almost everyone remembered the first few words and the last few words but hardly the words in the middle of the sequence. He then tried it again but with the words somewhat related and in groups of 3 with short pauses between the groups. The retention rate is much higher.

When we group information as chunks we remember more but we're still constrained by the 7+/-2 number for the total number of chunks retained in short term memory. Whether 7 digits at once or a group of 3 digits, 3 digits, and 4 digits which is just three chunks we're still below the magic seven number.

Likewise, the fanstastic game Brain Age on the DS has a great memory game. You're presented with 40 words for 2 minutes to remember and then you write back as many of the words as you can remember after the 2 minutes. I started out horribly with the brain age of 65 and could only remember a few. Once I started making silly sentences with the words (basically chunking it) I remembered almost all the words and got the brain age of 20.

There are some great comments in this interview with Cliff Atkinson on short-term memory research and how it relates to typical PowerPoint style presentations:

http://www.sociablemedia.com/articles_cowan.htm

Interesting about the phone numbers. It makes me think of when I give my number to someone else over the phone to write down; if I just blurt out all 7 digits, I usually get the "whoa, slow down there!" So I pause after the first 3 digits, then give the final 4, as do others when giving me their number. Is this because it's natural to only retain 3-4 digits at a time, or because phone numbers are already grouped that way?

People do definitely tend to look for patterns, and remember better with those. Way back in high school they once had about 100 magnets each with one obscure word printed on it. People always arranged them into phrases - usually attempting to make them sound naughty, but more importantly, people remembered the phrases even if they made no sense. Much more so than the words on the lone magnets which didn't make it into groups.

Patterns and groupings definitely have an effect. Maybe that explains why people can find a number in a phone book, where every listing looks the same, but can *never* find a feature under the Tools menu - because it's the leftovers, a bunch of mutually unrelated features that just didn't fit anywhere else.

An interesting article about memory tricks and some of the best memorizers in the world: http://www.discover.com/issues/apr-06/features/world-memory-championship/

I guess it's really only loosely related, but I found it fascinating.

A recent Scientific American article cited the 7+/- 2 rule and explained a little about the "chunking" workaround.

The Expert Mind:
http://www.sciam.com/print_version.cfm?articleID=00010347-101C-14C1-8F9E83414B7F4945

I agree that as it applies to software development we should try to minimize human memory requirements and when possible, design for better chunking.

As previously alluded to, the 7+-2 applies and fits quite well when you consider it works based on units of information.
When you chunk (as people tend to do with numbers) you can get to about 7+-2 chunks. If you do it with ideas that are harder to chunk, say a list of objects, without the use of memory aids (i.e. stories to create chunking and ascociation) you still tend to get the 7+-2.

I first ran into this when learning structured analysis. Yourdon uses this single study to claim 9 is the limit of processes on a DFD. But are we really that limited? Look at a county map (especially one from northern NJ). There's a zillion things on it and it makes it easy to figure out how to get from point A to point B.

Alan Le, we did something like that in a Psych class I took. Except we did three groups of letters.

Round 1: random 3 letter combinations.
Round 2: random 3 letter words.
Round 3: 3 letter words that told a simple story.

You can guess which round of trials had the best retention rate.

"I believe that you guys are nerds." ;) That word grouping (sentence) contains 7 words (chunks). Those 7 words are so much easier to remember than the following 7 letters: g q w e z p n. IMO, groupings makes things so much easier to recall.

Hmmm... Never thought of it before, but I was memorizing my bank account number (for endorsing checks), and was having trouble getting it to stick.

I finally did it by memorizing chunks - 5 digits, 4 digits, and 3 digits.

Another interesting fact about this 'seven' factor - Seems like u can fold a piece of paper (of any size - small or big) maximum of seven times only.

Recently took a memory test as a part of a control group for some medical trial the details of which are irrelevant. However, part of this test involved remembering and recalling dictated numbers, forwards and then backwards. As you'd expect, the longer the number, the more difficult, especially backwards, but what I found the real killer was when I didn't know the length of the number - I was already trying to stamp it into memory with a fixed pattern - when an extra digit appeared, boom - all gone.

>Seems like u can fold a piece of paper (of any size - small or big) maximum of seven times only

Aha! Not so! Check this out:

http://blogs.vertigosoftware.com/jatwood/archive/2005/11/18/Meet_Miss_Foldy_McFolderson.aspx

I can give you a string of 38 characters which you can memorise easily after seeing it only once:

"Aliens ate my baby sister's underwear."

Don't worry about numbers, worry about structure.

The mind as a relational database:
I would say we remember things the easist way possible.

Phone numbers are a particulairly good case of this. Most people will follow something along theses lines:
1)Who am I calling.
2)What context can be surmised (call their cell, their home whatever) for this example we will says we are calling susie at home.
3)Where is susie number. (usually you will have all but area code memorized.)
3a) You may be very familair with an area and know some common landline prefixes (second 3 digits) And relate the numbers that way.
4)You remember the area code by where susie lives. Ah she lives in Long Island so her first three must be...

As you can see we have this vast network of information going on in our heads. I would say we do not have a solid black and white limit on what we can remember. But as we go up in complexity and ambuguity it takes us longer to store something to memory. The precision for remember is not anywhere closely resembling a machines abilities. In this way we are very different from computers as its not the capacity that matters most but how hard it is to relate to what we alreay know.

joshua.r.thomas {at} gmail.com

I used to collect basketball cards when I was a kid, plus I was even nerdier and had some strange interest in what numbers were used by which players and such. So at this point, I can remember just about any string of numbers as long as I can convert it to a series of basketball players (baseball and football will do in a pinch). I still rememeber the combination to the toolbox on my college buddy's truck. Shaq, Price, Madkins.

At least some of the magic of 7 comes from the gods who, as we all know, live in the sky. Back in the day -- the day of the Sumerians, Chaldaeans, etc -- this is waaaay back in the day -- 7 was the number of planets -- mercury, venus mars, jupiter saturn, sun, and moon. This made 7 Very Sacred.

Many people do employ conscious memory visualisation techniques to help memories "meaningless" data.
Unconsciously, I think we do this automatically when remembering digit strings and such, although I have no idea what mechanism is used - needless to say, it's not very good (since there was never any evolutional advantage in being able to remember meaningless symbols).

I use a common technique called the "Major" system, which assigns a unique consonant sound to each digit, like so:
1 t, d
2 n
3 m
4 r
5 l
6 sh, j, (soft) g type sounds
7 k sounds
8 v, f sounds
9 b, p
0 s, z sounds

I did an aptitude test years ago, and was asked to remember longer and longer strings of digits. As they progressed, I was a bit surprised and didn't perform too well, but then I was asked to repeat the number forwards and backwards, and by that point, I had decided to visualise each string of digits as if I was dialling them on a phone keypad as she called them out. Doing it that way, I had perfect ultra-short term recall up to 15 digits or so when she stopped the test.

So I guess the key is, most of us basically suck at this if we don't use or devise a conscious aid for memorising the input somehow. This can be difficult when you're trying to organise such a system when a live stream of data is coming at you, of course...

A fascinating read on these topics is "The Mind of a Mnemonist: A Little Book About a Vast Memory" by A. R. Luria, about a Russian mnemonicist called Shereshevsky who started out as a journalist, and when someone asked him why he wasn't taking notes at a press conference, answered that he didn't need to as he could remember everything the speaker had said, and immediately repeated the entire speech from memory when challenged on the point. This guy experienced a condition known as synesthaesia where the senses are apparently not mutually exclusive and could see and smell sounds, taste colours and so on.
The French composer Olivier Messaien (whose music is very bizarre, but interesting) also had this condition.

Anyway, it seems that having synesthaesia allowed Shereshevsky to easily associate seemingly meaningless incoming data with known concepts, turning for example an abstract sound into a wave, or a clothes line upon which his mother was having some washing. And we know that we're very good at remembering visually meaningful events like this - that's how all mnemonic memory techniques work.
Man this was a long comment. :)

I meant to expand on that bit about the Major system.

When you encounter a number, say in this case, 5551212, you go through it, converting each digit to a consonant and construct words by filling in vowel sounds at will.

For example: 55 = "l l", 512 = "l t n", 12 = "t n", which could be expressed as "Lolly latin tin".

So one might imagine a hundreds of lollypops chanting in Latin, falling from a tin can.
The more ridiculous the image, the more exaggeration (hundreds...) the better such an image will stick in the mind. For longer strings, it's better to have separate images for each association (perhaps "lolly light", "light net", "net noah" (in the book I learned the system from, 2 is represented as "noah", for which you imagine an old man...)).

Then, you associate the starting point with the meaning of the number, say it's your office phone number, then you imagine arriving at your office to find lollypops all over your desk.

Easy peasy. Well no, complex, but after a while, you don't have to think about it so much.

There's an excellent PDF on this topic here:

"How magical is Miller's famous Seven for HCI issues?"

http://www.red-eye-reduction.com/assets/450_miller.pdf

Just like Albert once said;
never memorize things you can look up in books..

By the way, in Holland it isn't common (anymore) to write phone numbers in chunks. We have one chunk (the area code) and then a chuck of 7 numbers. So, are we generally smarter? Do we have more brainspace?

I think the answer is a definite yes.

And how about the 10 commandments, is it impossible to live a sinless life, because we can only remember 5 to 9 of them? Think about it. If you take this post beyond it's original point (which is in my opinion; keep it simple) it just doesn't make sense, just like this comment.