One of my favorite exercises is called a PMI, which stands for Plus, Minus, and Interesting. Its objective is to encourage people who strongly favor or oppose a particular idea to consider other perspectives. I found this exercise in Edward de Bono's book de Bono's Thinking Course—a book that's chock full of activities that will help you stretch your thinking and have fun while doing so.

The PMI is a highly effective and elegantly simple three-minute exercise. It entails having teams spend one minute identifying as many pluses, or good points, as they can about a certain idea; then another minute identifying all the minuses, or negative points; and finally a third minute identifying aspects of the idea that are neither positive nor negative—merely interesting.

We may think we already do a good job of considering ideas from multiple perspectives, but de Bono suggests otherwise. His premise is that once we latch onto a particular opinion, we tend to use our ability to think primarily to support and justify that opinion. In doing so, we become closed to opposing viewpoints. Why consider other views after all when we know we're right?

Though we may be close-minded at times, once we become aware of the possibility of an alternative perspective, we have to acknowledge its existence. As de Bono puts it, "Once an idea has been thought and put down under any of the headings, that idea cannot be 'un-thought' and it will come to influence the final decision."

Here's an example of the PMI in action: I was facilitating a session for a group of IT personnel and their customers to help them work together more effectively. One of the concerns my client (the IT director) had expressed was that the customers were relentlessly negative about following IT standards for development and support. I was instructed to "help them see the value of standards." His concern was valid; yet, in interviews I had previously conducted with the IT staff, I'd detected a "standards at all costs" perspective—a viewpoint perhaps as extreme as that of the customers.

To conduct the PMI, I had the group divide into teams of four or five people, with both IT and customer personnel on each team. I described de Bono's ideas about closing ourselves off to opinions we disagree with and emphasized his point that once we think an idea, we can't "un-think" it. I identified IT standards as the focus of the exercise and explained the three one-minute rounds. First, they'd identify all the pluses they could, then all the minuses, then all the interesting points. I told them I'd let them know when each round had ended and when to begin the next round.

Although I didn't label the exercise as a competition, there's something about being divided into teams that causes participants to become competitive. The result was three minutes of a noisy high-energy frenzy as each team raced to come up with longer lists than the other teams.

This exercise may seem overly contrived. It's not. de Bono offers several examples in which people adamantly committed to a particular point of view found themselves reconsidering their perspective as a result of doing a PMI.My favorite example involved a group of thirty boys, ages ten and eleven. They were asked what they thought of receiving $5 a week just for going to school. Not surprisingly, the boys loved the idea. Then de Bono had them do a PMI on the idea.

Amazingly, by the end of the three minutes, twenty-nine of the thirty boys disliked the idea and for a multitude of unusually mature reasons: other prices, such as the cost of meals, would increase; teachers would have to be paid less; and parents might react by withholding presents or pocket money. Oh yes, and the bigger boys at school might beat them up and steal their money. The boys might never have considered these ideas without participating in this exercise.

Importantly, as de Bono notes, the boys achieved this change in mindset on their own with no outside intervention or influence. And that's been my experience as well in running this exercise in organizations.

One minute per round may seem like too little time, but the very brevity of the exercise is one of its strongest features. People's attention becomes riveted on carrying out the exercise and one minute allows just enough time to jot down responses without analyzing or judging them. For that reason, it's important to adhere to the one-minute per round time limit, rather than soliciting people's views about the plus and minuses and discussing each one in turn.

In debriefing the PMI with the IT/customer group, I had teams report on their pluses, then their minuses, and finally their interesting points, and as they did, I recorded them on a flip chart. Strikingly, it was the customers who reported some of the positives: "We'll save time because we'll know the steps we need to take." And the IT personnel reported some of the negatives: "Some standards are overly complex relative to the customer's need."

In fact, at several points, customers seemed eager to explain to their co-workers on other teams why they felt strongly about their pluses. And some of the IT staff now defended some of the minuses they might not have even considered before.

One of the important "ah-ha's" in this exercise is that an idea can be positive for some people and negative for others. For example, although two groups listed that standards create boundaries, one group listed it as a positive, and the other as a negative. Both perspectives are valid, and the very fact of its being seen as a positive by some and a negative by others provided food for thought regarding how standards can help—or hinder.

With customers acknowledging pluses they hadn't previously considered and IT staff now recognizing that certain standards could overly constrain their customers, the stage was set for them to jointly consider standards from a more open-minded perspective.

Be on the lookout for situations in which you, your team, your department, your customers, or other groups you interact with have taken a stand strongly favoring or opposing a particular idea or approach. A PMI might be just the exercise to help shed light on alternatives. Best of all, no one can claim they don't have the time.