Here is an interesting link I just came across: http://www.scientificamerican.com/article.cfm?id=the-power-of-introverts

What do you think of this?

The article is about introversion, and it basically states that if you want to foster creativity at school, or at a working place, then brainstorming in groups is not necessarily the best way. According to the text, the best ideas come to people who take time for themselves to think and jot their thoughts down, and who don't have any social pressure to be accepted by the other members of a group.

From my own experience in both brainstorming alone and within a group, I'd say I could concentrate better alone. On the other hand, there is also some merit in group think, if there are low social barriers between the group members.