How many items should go in a menu?

"A lot of people think 7 ± 2 (i.e., between 5 and 9, with a preference for 7).
NO! It isn't! And here I will explain why. But first I have to give a very short history lesson"

Well, the thinking is that if a person can memorise 7 ± 2 items, then that is what should be in a menu. That’s the maximum amount that can be retained in short term memory without it being “processed” into long term memory.

Yup, people always get this wrong ...