Thought you’d like to see this sketch I found in my picture folder.
It’s a simple (if not silly) way to plot how, during the brainstorming process, there is shift up and down between gathering many ideas to narrowing to fewer ideas.
[click for larger view]
The technical terms for these thinking styles is divergent production (going in different, many directions) and narrowing ideas is called convergent production (closer, coming together).
These terms were coined in the 1950s by US psychologist, Joy Paul Guilford as part of his “Structure of Intellect” theory.