"Experiment after experiment has shown that people in brainstorming sessions produce fewer and lower quality ideas than those working alone (Furnham, 2000). Here’s why:
- Social loafing: people slack off to a frightening degree in certain types of group situations like brainstorming.
- Evaluation apprehension: although evaluation isn’t allowed in a traditional brainstorming session, everyone knows others are scrutinising their input.
- Production blocking: while one person is talking the others have to wait. They then forget or dismiss their ideas, which consequently never see the light of day.
Also it emerges that groups do have a natural talent, which is the evaluation of ideas, rather than their creation."
- found on http://hitenshah.name/