That practice is triangulation. Picture a typical office, in which two people are talking. Lenore, the office's owner, sits behind her desk. Arlen is ensconced in a chair. Because their conversation is not the stuff of rumors or gossip or deep, dark intrigue, the door stands open. Then Clarice pokes in her head to ask Lenore a "quick" question. They chat. And slowly, it dawns on Arlen that he is trapped. The interruption has become a discussion--discussion of a subject that neither interests nor concerns him. Yet in the one or two minutes it takes Arlen to realize this, the opportunity for a rapid, graceful exit disappears. Furthermore, the ability to depart without drawing attention to his third-wheel status fades with each passing moment. Arlen has been triangulated.

Triangulation is largely a function of hard-wired politeness. Most people consider it rude to stand up and walk out, although the interruption was ruder. Workplace power structures exacerbate the situation. People can be triangulated only if they make no contribution to the new subject of discussion. If that subject is skiing (and they don't ski), then sitting passively is dull and unproductive. If the subject is work-related, however, their silence can be embarrassing, and quitting the scene calls further attention to it.

That is especially true when one of those talking is the boss and one is a peer, whose familiarity with the topic stands in uncomfortable relief against the ignorance of the person being triangulated. Imagine your general manager sitting in mute misery while you, the CEO, hover in her doorway soliciting another executive's opinion on some industry development the GM somehow missed.

Another psychological barrier to escape is the prospect of sidling past the interloper or asking him to stand aside. (If an employee is triangulated in his own office, only a ringing phone or fire alarm will release him.) Two-door offices, although otherwise impractical, would alleviate that problem. But office design doesn't cause triangulation. People do. The smart ones will have an escape strategy--just a few prepared words ("Let's pick this up later," or "I just remembered I have to make a phone call," or "That's it for me!") and a set time period (no more than two minutes) in which to speak them. If employees abide by the same rules every time they get trapped, they can avoid the whole should-I-leave-shouldn't-I-leave-how-should-I-leave inner debate. Expeditiously announcing their departure may also guilt the conversation to a close.

The paucity of studies on worker productivity lost to triangulation is not surprising (this is, after all, a term we are proudly coining). And because few people would dare triangulate the CEO, you may not have experienced it yourself. But triangulation happens routinely to everyone beneath you, and it costs the company. So discourage employees from interrupting conversations, even for "a quick question," and set the example with your own behavior. Thinking about popping into an office where two of your staff members are talking? Stop first and recall the advice of Dionne Warwick. Then walk on by. Walk on by.

Leigh Buchanan is an Inc. editor-at-large. She can be reached at