You are probably brain-dumping, not brainstorming.
Have you ever shown up to a meeting to "brainstorm ideas", only to have the same old ideas come out? Why is it that Brainstorming Doesn't Work? It could be that brainstorming really doesn't work, but I've come to recognize that the real problem is that people are not really brainstorming. They are "Brain-Dumping".
Brain-Dumping is a Waste of Time.
Brain-dumping occurs when people come in, share their ideas, then select from those ideas. Although there can be some interesting breadth to the ideas, if people come in with diverse experience and diverse inspiration, unless the "storming" part of a brainstorm occurs, nothing new is created.
Brainstorming requires thinking hard, building on ideas, playing with ideas, thinking about things in new ways.
If your goal is actually to come up with new ideas, not just understand what ideas you already have, you need to facilitate a real brainstorm. A good facilitator can make an enormous difference in getting people to stretch their thinking and break through the old ideas.
To facilitate an effective brainstorm, you need to influence what activities the group has done to prepare for the brainstorm, you need to set the stage and timeframe (clue: this stuff takes a lot more time than you think), you need to be clear on the rules (and share them), you should have a plan for how to keep pushing the boundaries, you should have some brainstorming fodder available to prompt people, you should have a plan for how to narrow down to the really novel ideas, and a plan for what actions to take coming out of the brainstorm to ensure that something really valuable happens.
Ideally, you also have set yourself up for success with some good facilitation skills to handle the inevitable challenges that arise when bringing a group together to spark collaborative ideation.
For your next brainstorming session - try moving beyond a brain-dump.
Come join me in a half-day course in facilitating effective brainstorms that will give you more skills and practice to help set yourself up for successful breakthrough ideation sessions!