“There’s only one problem with group brainstorming: it doesn’t actually work. […] Forty years of research has […] shown that performance gets worse as group size increases: groups of nine generate fewer and poorer ideas compared to groups of six, which do worse than groups of four, [which do worse than people working individually].”
“[Despite] all these years of evidence that conventional brainstorming groups don’t work, they remain as popular as ever. Participants in brainstorming sessions usually believe that their group performed much better than it actually did.”
-Susan Cain, Quiet (p. 88-89)