There was an interesting thread over at David Allen Co’s GTD forum recently - it was focused on what contexts people were using. As the thread got longer, the topic got wider, until they were discussing Miller’s Theory of 7 (+/-2). Now, I don’t remember ever hearing it called such, but I do remember from my early leadership days that you could successfully lead/manage 5-9 people/projects/etc. Fascinating to think that there’s actually theory and experimentation behind this!
On the forum, Andersons pointed out the following:
There are gazillions of studies confirming Miller’s short-term memory limitation of 7 +/- 2 items, but yes, they are distinct items (not necessarily unrelated). “Chunking” is one way we increase our capacity to use information, by grouping related items into a single higher-order one. This is why hierarchical organization is so powerful. If you give someone a list already grouped, they will remember many more items than if the list were ungrouped and unsorted.In real life, the limit is probably more like 5. We can get people to expend extra effort and energy to do their best in lab tests, but in real life it’s too expensive to perform at our lab-best all the time. In our lab, we literally pay subjects bonuses for better performance. For short bursts of time they do their best, then head off to the pub when they’re done. :-)
Later, Andersons went on to cite the source for Miller’s Theory:
The oft-cited paper by Miller was published in Psychological Review in 1956, volume 63, pp. 81-97: “The magical number seven, plus or minus two: some limits of our capacity for processing information.”
I was particularly fascinated by the concept of experimenting with such things, and how 5 really is the good number, because we can’t be expected to work at “experiment best” all the time.

