You’re probably brainstorming all wrong. Chances are you’re using some form of the rules that were initially devised by the adman Alex Osborn that started in the 1950s. His process sounds intuitively reasonable: Get a bunch of people together. Have them throw out ideas without worrying about constraints. Don’t criticize the ideas, just build on them. Don’t worry about how strange the ideas are, just come up with as many as you can.
The problem with these rules for brainstorming is simple: They frankly don’t work. We know now a good deal more about human psychology and brain science than Osborn did, but we’re still brainstorming as though we don’t. Many studies over the years have actually documented a productivity loss from his method of brainstorming. Groups that follow Osborn’s rules come up with fewer ideas—and fewer good ideas—than the same number of people working alone.