Topic: Reasoning for a 7 digit phone number
 Message: Posted by: cajuninms (Apr 10, 2004 12:00PM)
Ok I think this is the reasoning behind why phone numbers have 7 digits

the average human brain can only memorize for long term up to 9 things at a time..that is why they chose 7

correct me if I am wrong but I think that is right
 Message: Posted by: Bill Palmer (Apr 24, 2004 08:15PM)
You are wrong.

The average human brain cannot remember where the shift key or the punctuation marks on the computer happen to be.
 Message: Posted by: MacGyver (Apr 27, 2004 01:27AM)
Did you know that 72.9% of all statistics are made up on the spot???
 Message: Posted by: EmmanuelM (Aug 10, 2004 04:47AM)
[quote]
Ok I think this is the reasoning behind why phone numbers have 7 digits
[/quote]

Don't forget there are other countries whose "rules" are different even though inhabitants have brains similar to yours :)

So, the fact that, say, in France, phone numbers have 10 digits is something to deal with for your reasoning. Actually, the phone numbers are here considered as 5 numbers between 00 and 99, not 10 digits. You'll never hear someone say "0-1-4-2-..." but "01-42-...". So we're indeed back under 7...
 Message: Posted by: Metalepsis (Aug 10, 2004 11:55AM)
Why, Bill, why!?!?

Why, must you make coffee come out my nose?

This might have something to do with "numbering plans".

M
 Message: Posted by: dr chutney (Aug 10, 2004 02:36PM)
" coffee come out of my nose ? "

I fear I have wandered into the Surreal section of the Café.

In which case the answer is, almost certainly, Deckchair!
 Message: Posted by: ddyment (Aug 11, 2004 10:15AM)
Cajuninms wrote:[quote]Ok I think this is the reasoning behind why phone numbers have 7 digits

the average human brain can only memorize for long term up to 9 things at a time..that is why they chose 7[/quote]
There is actually some validity to this. In the field of psychology, there's a [url=http://www.well.com/user/smalin/miller.html]very famous paper[/url] on the number seven.

... Doug
 Message: Posted by: EmmanuelM (Aug 11, 2004 12:06PM)
[quote]
There is actually some validity to this. In the field of psychology, there's a [url=http://www.well.com/user/smalin/miller.html]very famous paper[/url] on the number seven.
[/quote]

I have a comment about this, taken from my life in the 90's as a student in the field of experimental psychology (and related to why I choosed to quit this domain ! :) ) :

Do not forget that this study was conducted in the 50's. And I think you could have spectacular differences if it was done again now, because of the arrival of... video games. In particular, today's students who practice console or PC video games are now incredibly trained to tasks involving memory (in particular spatial memory), 3D geometry, etc..., compared to those of the 50's [Psychology studies' subjects often are.. psychology students !]

Once I had to do a study on the effect of correcting lens on perception, using a set-up displaying distorted 3D objects, etc.. and wow, the biggest correlation between any factor and the quality of perception seemed to be the "habit" to play video games, something the lens maker was not much caring about :-(

It was even more "embarassing" for another student who was conducting research on spatial memory (ie : what are the mechanisms to memorize a path in a town etc..). Clearly there was a problem to know beforehand whether or not a subject was a naive one or an expert, because even a little practice of video games would bias the results a lot.

So, maybe, in the next years, magicians will have to face more and more adults who will have capacities well above today's standard ones in terms of 3D or photographic short-term memory. Maybe substituting the 6S/9C pair with the 6C/9S pair is not going to work any longer !
 Message: Posted by: Scott Cram (Aug 11, 2004 10:30PM)
[quote]
On 2004-04-10 13:00, cajuninms wrote:
Ok I think this is the reasoning behind why phone numbers have 7 digits

the average human brain can only memorize for long term up to 9 things at a time..that is why they chose 7

correct me if I am wrong but I think that is right
[/quote]

First, if you include the area code, phone numbers have 10 digits.

Second, I always figured that the reasoning for having 10 digit phone numbers was that the total population of the U.S. was a 9-digit number (roughly 300,000,000), and this allows for everybody to have several phones, and still allow for population growth.
 Message: Posted by: dr chutney (Aug 12, 2004 02:57AM)
In the UK we're blessed with 11 digits, a 5 digit area, or STD, code and a 6 digit number. We have 20% of the US population but we've still had to endure phone number changes in recent years because numbers were running out, and they're even talking of an extra STD code for London again.

The reason we have 11 digits in the UK is nothing to do with memory but poor telephone organisation to begin with.
 Message: Posted by: dlhoyt (Aug 12, 2004 01:26PM)
As I recall the history of telephone numbers back in the 1940s we had 6 digit numbers. The first two digits were encoded with a word mnemonic; e.g., 434715 was written as HE-4715 and remembered as Hedrick 4715. The Bell telephone Co. had a standard set of prefix mnemonic names that were used nationwide. The six digit system became inadequate to handle the increasing number of telephones, so a third digit was added to the prefix. HEdrick 4715 became HEdrick 2-4715. Sometime in the 1950s or '60s the telephone people discovered that we could actually memorize numbers and the mnemonic prefixes were abandoned. Shortly after this time touch tone dialing was introduced along with the area code and direct distance dialing, expanding the actual phone number to 10 digits. But, by breaking the 10 digits down into a 3-3-4 pattern people were able to easily remember the longer numbers. This pattern still falls within the magic 7 chunks of information that seems to be the limit of retention in short term memory.
 Message: Posted by: Metalepsis (Aug 18, 2004 03:11PM)
1. Coffee came out my nose because I was suddenly (while drinking coffee) induced to laugh at the sarchasm (you know...the gulf between your audeince and the punchline).

2. Numbering Plans.

3. Dr. Chutney, our UK numbering plans are integrated with Europe's, hence the difference. This means we must accomodate MORE population than America, not less. In fact see 2.

4.DLhoyt is correct about the original history, before it was recognised that NUMBERING PLANS were needed. Hmmm....I wonder if there is an organisation that is responsible for organising this stuff...mayeb I could find it on google if I did a search...or maybe some guy named Metalepsis (five points if you know the meaning of this word without looking it up) is a nutcase who types random messages on a magic board...actually I do (it's markov chain generation with SS7 engineering manuals as the seed for the chains.)

M
 Message: Posted by: Metalepsis (Dec 1, 2004 11:43AM)
Well, that was effective. Is anyone still interestd in this subject in a rational way?

M
 Message: Posted by: Parson Smith (Apr 8, 2005 09:30PM)
Shame on you, Bill.
Tsk, tsk, tsk.
 Message: Posted by: Parson Smith (Apr 8, 2005 09:31PM)
The last post was only about 11.5 months late.
 Message: Posted by: nums (Apr 14, 2005 09:39PM)
WHile we do remember 10 digits for a phone number, however I believe we still only have to remember 7 due to the fact that the area code is the same for most. we also have a strange way of remembering numbers as I remember patterns on the phone opposed to the phone numbers. I just today was asked about a friends # and had to air dial to get it. Does any one know why the # pad on the keyboard is different from a keypad on the phone??

Jeff
 Message: Posted by: Mr_Matthew_Charles (Apr 20, 2005 03:23PM)
[quote]
On 2004-04-27 02:27, MacGyver wrote:
Did you know that 72.9% of all statistics are made up on the spot???
[/quote]

haha you made that up on the spot, you made a topical joke!