Magic Number 7!

Ever since we first learned about 'Miller's Magic Number 7' I have been intrigued by its simplicity. I like the fact that such a simple experiment can measure such a complex process as short-term memory and that it can be replicated and get consistent results time and time again.
The concept is simple: to test capacity of short term memory by digit strings that increase in length by one digit each trial ie. seeing how many digits and individual is able to hold in their STM. Miller stated the average number of digits was the magic number 7 (+/- 2).
I replicated this experiment with 4 of my friends today. Although conditions were not controlled and there was little ecological validity, I enjoyed playing the role of an experimenter and got the expected result. 3/4 of my friends recalled digit strings up to 7 numbers long (the magic number 7) and 1/4 recalled 5 digits (7-2). It's great how this simple experiment works so well!