Ask Tog, October, 1998
Seven +/- 32768
George Miller's 1956, seminal article, "The magical number seven, plus
or minus two," suggested that people have an inherent limit to how many
numbers they can comfortably handle at once.
The Phone Company suggested, around the same time, that, had the
automatic telephone switch not been invented, half the population of the
United States would be working as telephone operators.
Fast-forward forty years. Phone number sequences have changed from two
letters and five numbers (DIamond 3-1608) to such unmanageable sequences
including country codes, carrier codes, area codes, credit card numbers,
voicemail access codes, passwords, and message-playback codes.
If Miller was right, by now we should be damned uncomfortable. We are.
If the Phone Company was right, by now the entire population of the
United States should be telephone operators. Guess what? We are.
Miller, George A. (1956). "The magical number seven, plus or minus two:
Some limits on our capacity for processing information." The
Psychological Review, 63, 81-97. Also at