I'm working on a game that's designed to exercise the player's short-term memory. In the core game loop, I present the user with a random set of items (anywhere from 3 to 30), and after they click start, ask them to regurgitate that set of items.
The items themselves are simple but arbitrary / semantically meaningless, eg. four colours (red/blue/green/yellow), or four arrows (up/down/left/right).
As I increase the game difficulty, what I want to know is: is it more difficult for humans to memorize more groups (eg. five groups of two items each), or smaller groups with more items (eg. two groups of five items each)?
I recall learning that short-term memory is generally seven items (plus or minus two, eg. 5-9 items) but I'm not sure how grouping/chunking affects that.