If you've ever participated in a brainstorming session that yielded fewer ideas than anyone would have liked, a lack of creativity might not have been to blame. Certain disruptive personality types could have doused the idea generation process instead, say Mitchell Rigie and Keith Harmeyer, authors of "SmartStorming: The Game-Changing Process for Generating Bigger, Better Ideas."

Rigie and Harmeyer, who each have about 25 years of experience working in advertising and marketing, say collectively they've participated in several thousand brainstorms and several years ago set out to research brainstorming best practices. Here are six kinds of people you want to keep out of your next creative huddle.

Attention vampires. These folks are naturally attention-seeking, like to talk, and usually dominate a session. "They tend to always kind of bring the spotlight to themselves. So it's a little difficult to rein them in," Rigie says.

Wet blankets. These people are naysayers who will give you a dozen reasons why an idea is bad. "They tend to be what we call defect inspectors," Rigie says. "No matter what you put out there they'll find some kind of defect and it really does dampen the enthusiasm level of the group."

Idea assassins. While closely linked with the negativity of wet blankets, idea assassins aren't nearly as thoughtful with their criticism. Instead of offering ways of improving other people's ideas, they like to poke holes in them thinking that they're bringing a voice of reason to the group. "We always say an idea assassin is like someone at a birthday party that goes around and pops the balloons. They just want to shoot down an idea as quickly as possible so we can get on to one that makes sense."

Dictators. These are often individuals in a supervisory position. They like to choose their own ideas, which eventually stifles others' creativity and enthusiasm. Harmeyer says he and Rigie once worked with the president of an ad agency who insisted on sitting in on every important brainstorming session, but he would preface each meeting by telling participants that the old adage "There's no such thing as a bad idea" isn't actually true. In fact, he would say "There are very bad ideas that should never be spoken out loud." As a result, nobody contributed much and all the boss's ideas ended up getting selected.

Obstructionists. If something can be overcomplicated, these people will do it. "They overthink [an idea], they want to analyze it to death, and that's simply just not the most productive way to be in what should be a spontaneous free-sharing environment like a brainstorm," Harmeyer says.

Social loafers. These people come to the meeting and just take up space, not really contributing anything of value.

How to Deal With Idea Killers

Harmeyer and Rigie say the most obvious thing to do is to not invite idea killers into a brainstorming session to begin with.

That's not always possible, of course. Here's what else to try.

Establish rules of the game. The first thing a meeting facilitator needs to do in a brainstorming session is set up the framework for what kinds of behaviors are acceptable and not acceptable. Actually, you should do this before any meeting, not just before brainstorming. Rules should be written down and posted somewhere in the room.

Aim for quantity over quality. For every 100 ideas you generate maybe only a handful will have real merit. "We tell people there's no such thing as a bad idea because even the worst sounding idea can have the seeds of a really good idea within it, so you have to give it a chance," Rigie says.

Embrace wild and audacious ideas. "We like to say you never know how far you can go until you go too far," Rigie says. "So it's always better to take an idea that's maybe gone too far to the edge of absurdity but bring it back because usually there's a way to make a wild idea work or to ground it a little bit."

Cultivate an egoless environment. Who created an idea should be irrelevant. Brainstorming is by nature a group effort.

Go non-verbal. Harmeyer says his favorite exercise to use with clients is one called "brainwriting." Someone poses a challenge to the group and each person writes an idea for solving it, then handing his or her paper to the person on the left. Everyone reads their neighbor's idea and adds to it--maybe an improvement to the idea or an entirely new one--and this process continues until everyone has their own paper back in hand.

"So [in a group of eight] within 10 to 15 minutes you have 64 ideas on paper and there's been no need or opportunity for discussion, criticism, or excessive conversation," he says.