In communications, two, three and five are the magical numbers

Long lists (top 10 or longer) are popular with blogs. As checklists, they’re fine, but as communication tools, they violate one of the mantra’s of professional communication. A reference article [1] from psychology alerts us to the limits of short-term memory, where we can store typically seven-plus-or-minus-two items.

In [2], J-L Doumont argues that ’seven’ is an asymptotical limit, and should not be interpreted as ’seven items is fine’. He proposes 5 as a practical limit, and takes us through the integers:

zero is perfection
one is focus
two is a single binary alternative
three is the simplest form of complexity
four is a square, a combination of 2 binary choices
five is a handful

Beyond five comes six, to be used exceptionally in cases that would otherwise require jumping through hoops to avoid a sixth item. Anything equal to or larger than seven is many. Be ready to loose your reader / listener.
If five is the maximum, it doesn’t mean ‘five is always fine’. If possible, two or three will always be better.

References
[1] G. A. Miller, The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information, The Psychological Review, 1956, vol. 63, pp. 81-97
[2] J-L Doumont, Magical Numbers: The Seven-Plus-or-Minus-Two Myth, IEEE Transactions on Professional Communications, 2002, Vol 45 No 2, pp 123 - 127