Brainstorming can be a productive way to solve problems; generate new products, services, or processes; and capitalize on golden opportunities. But far too often the process is hijacked by disruptive individuals who undermine collaborative efforts.

Have you ever found yourself in a brainstorming meeting that felt dominated and controlled by an attention-seeking personality? You are not alone. It seems every company or organization has its share of those idea killers.

Most of those strong-willed participants likely believe they are keeping the group on track with candid insights or opinions. What they fail to realize is they can inject so much negativity, judgment, or distraction into a session that they derail a group’s idea generation momentum…and/or kill fledgling but promising ideas.

In our twenty years of brainstorming experience working with many of the top Fortune 500 companies, we’ve identified what we call a ‘rogue’s gallery’ of six disruptive personality types you might want to avoid inviting to your next brainstorming session.

See how many of these troublesome types you can recognize:

Attention Vampires—They always want to stand out, be in the spotlight, and be the center of attention. It’s always about them. Attention Vampires can smother a brainstorming session by dominating the conversation, excessively pushing their ideas, and ultimately sucking the life out of the whole group.

Wet Blankets—These are the pessimists who see the flaws in everyone else’s ideas. Nothing goes unscathed. Wet Blankets have the unique ability to instantly dampen the enthusiasm level of a session. They are discouraging and depressing, and the majority of their comments don’t hold water.

Idea Assassins—These seasoned killers love to shoot down ideas…anyone’s and everyone’s. Under the pretense of being constructive, they will find flaws, poke holes, and pick apart promising ideas until they bleed to death. These are the same people who go to birthday parties and enjoy popping the balloons.

Dictators—They love every idea—as long as it’s theirs. These totalitarians feel they are the only ones with good ideas, or good taste, for that matter. Everyone else’s contributions need to conform to theirs or risk being shot down. Many bosses unknowingly become Dictators in meetings (not on purpose, but their role in the company makes it too easy.) Such idea overlords are to be avoided at all costs. It’s not wise to let them dictate a negative outcome for your group.

Obstructionists—To them, nothing is simple or easy. They overcomplicate conversations and procedures and bring up extraneous facts or considerations that derail the flow of the group. Obstructionists overthink, overspeak, and singlehandedly dead-end otherwise promising sessions.

Social Loafers—These are the people who show up for a brainstorm session, but rarely participate in the generation of new ideas in a meaningful way or contribute much of substance. They usually sit back, appearing bored or aloof, and let others do the heavy lifting.

Any one of these problematic personalities can undermine the focus and collaborative efforts of a group. While it’s difficult to prescribe a simple, one-size-fits-all formula for handling all these different personality types, there are a number of practical steps you (or the session leader) can take to more effectively manage disruptive behaviors to keep your sessions on track and productive:

Forget the Invitation—The simplest way to avoid problematic personalities in a session is not to invite them in the first place. If it’s the boss or a senior-ranking person, assure him or her that you will share any good ideas the group generates afterward. Or here’s a novel idea: You might simply tell the truth.

Establish “Rules of the Game”—Introducing a few rules at the start of a session can help eliminate, or at least significantly minimize, disruptive behavior problems. Some popular and effective brainstorming rules are ‘Suspend all judgment,’ ‘There’s no such thing as a bad idea,’ ‘Go for quantity, not quality,’ and ‘Embrace wild, audacious ideas.’ It is also important to reinforce the fact that brainstorming is a collaborative group effort; so the origin of any idea is irrelevant.

Impose a Short Talking Moratorium—If a participant is dominating the session, being overly negative or judgmental, or being an attention hog, quickly shift gears and introduce a nonverbal brainstorming exercise. For example, ask everyone to silently write down five ideas and then read their favorite aloud.

Segregate Strong Personalities—A great tactic for managing strong personalities is to divide the group into smaller teams of three. Deliberately assign any disruptive personality types to the same team…and watch the sparks fly.

Create a Self-Policing Group—Explain early in the session that if anyone exhibits any type of negative or judgmental behavior, he or she is to be bombarded mercilessly by the group with crumpled paper balls.

Encourage everyone in the room to participate in order to create a self-policing environment. While it may seem silly, this technique is a playful, good-natured way to minimize transgressions and allow the group itself to enforce the ‘No Judgment’ rule.

Engage in Silent Idea Voting—Evaluating and selecting ideas can become problematic when strongly opinionated individuals assert their preferences or biases. Instead of ideas being selected based on merit, the evaluation process can devolve into a Darwinian contest for favorites. Using a silent voting technique can help eliminate coercion and level the playing field for everyone to vote.

Invite a “Dream Team” vs. “The Usual Suspects”—When planning your next brainstorm, why not invite your dream team? This group would be made up of knowledgeable individuals who possess a collaborative, can-do attitude—even if they are typically far removed from the project at hand.

Let the usual suspects, the mixed bag of colleagues or teammates you usually invite by default, sit the session out. Shaking things up can have a dramatic impact on a group’s ability to collaborate freely, share, discuss, and build upon one another’s ideas

A brainstorm is only as good as a) the people in the room and b) the tactics you use to minimize bullying and self interest, stimulate creativity, and bring out the best ideas in everyone. Don’t make these decisions lightly. Invite the right people to the session and manage—or better still, politely forget—the idea killers. The solutions that emerge will astonish you.